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[SeattleRobotics] SRF08 beam angle

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  • Alejandro Alonso Puig
    Hi all, I ve got a question. Does anyone of you know by experience what is the angle of detection of the sonar ranger SRF08 from Devantech?. I have found some
    Message 1 of 17 , Dec 1, 2003
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      Hi all,

      I've got a question. Does anyone of you know by experience what is the angle
      of detection of the sonar ranger SRF08 from Devantech?.

      I have found some information on the Internet, but I don't believe what I'm
      reading. I found that the angle detection is of about 40 degrees, but in my
      tests I find it is about 100 degrees. SRF04 seems to really have 40 degrees
      of beam angle, but not SRF08.

      The most interesting information I found about the beam pattern is the graph
      taken from the manufacturer:
      http://www.robot-electronics.co.uk/htm/sonar_faq.htm but Devantech really do
      not give a clear figure for the beam width. I just see that depending on the
      decibels the beam is wider on narrower. My though is that the transducer is
      used at about -18dB and therefore the cone width is about 100 degrees.

      But I'm not sure I'm doing correctly or my unit is wrong in some way.

      Could someone please confirm from experience the beam width?

      Thanks a lot in advance

      Alejandro Alonso Puig
      http://mundobot.com
      alejandro.alonso@...




      -----Original Message-----
      From: Doug Evans [mailto:DEvans@...]
      Sent: sabado, 04 de octubre de 2003 0:55
      To: Tom Capon; seattleRobotics@yahoogroups.com
      Subject: RE: [SeattleRobotics] MPLAB error message


      you need a colon ':' character to define the label, if you are using MPASM.

      you should have

      KBD_1:

      not

      KBD_1

      -de


      -----Original Message-----
      From: Tom Capon [mailto:robot@...]
      Sent: Friday, October 03, 2003 4:32 PM
      To: seattleRobotics@yahoogroups.com
      Subject: Re: [SeattleRobotics] MPLAB error message


      Well, it gives errors from this code:

      goto KBD_1
      bsf KBD,0x07
      goto KBD_2
      KBD_1 bcf KBD,0x07
      KBD_2 decfsz ISRtmp1,W ; skip if ISRtmp1 == 1

      I think I will simply retype it or something and see what happends.

      At 08:22 AM 10/3/03 -0700, Jim McBride wrote:
      >Make sure you don't have a case sensitive issue. In school I gave up and
      >just coded everything in upper case to keep from getting bit.
      >Have a look in your include file for your processor. You may find some
      >answers there as well.
      >Jim
      >
      >At 04:54 PM 10/2/2003 -0700, Scott Pierce wrote:
      > >Then the GOTO statement probably points to a label which is not defined,
      > >for example you could have a line that says: GOTO Delay; but Delay isn't
      > >defined so the assembler doesn't know where you're trying to go to.
      > >
      > >Scott Pierce
      > >
      > >At 07:42 PM 10/2/2003 -0400, you wrote:
      > > >Actually, it gives the "symbol not previously defined" error to GOTO
      > > >statement line labels that are a few (or a lot) of lines down. I'll
      > > >probably end up rewriting a bunch of it anyway, I'll come back if it
      still
      > > >doesn't work.
      > >
      > >
      > >Visit the SRS Website at http://www.seattlerobotics.org
      > >
      > >To unsubscribe from this group, send an email to:
      > >SeattleRobotics-unsubscribe@yahoogroups.com
      > >
      > >
      > >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
      >
      >
      >
      >Visit the SRS Website at http://www.seattlerobotics.org
      >
      >To unsubscribe from this group, send an email to:
      >SeattleRobotics-unsubscribe@yahoogroups.com
      >
      >
      >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/


      Visit the SRS Website at http://www.seattlerobotics.org

      To unsubscribe from this group, send an email to:
      SeattleRobotics-unsubscribe@yahoogroups.com


      Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/


      Visit the SRS Website at http://www.seattlerobotics.org

      To unsubscribe from this group, send an email to:
      SeattleRobotics-unsubscribe@yahoogroups.com


      Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
    • Paul R. Lundgren
      In some cases the half beam angle is specified (makes the specs look better). Also the beam angle is usually specified at the -3 dB points. Hagar
      Message 2 of 17 , Dec 1, 2003
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        In some cases the half beam angle is specified (makes the specs look better). Also the beam angle is usually specified at the -3 dB points.


        Hagar

        Alejandro Alonso Puig wrote:

        > Hi all,
        >
        > I've got a question. Does anyone of you know by experience what is the angle
        > of detection of the sonar ranger SRF08 from Devantech?.
        >
        > I have found some information on the Internet, but I don't believe what I'm
        > reading. I found that the angle detection is of about 40 degrees, but in my
        > tests I find it is about 100 degrees. SRF04 seems to really have 40 degrees
        > of beam angle, but not SRF08.
        >
        > The most interesting information I found about the beam pattern is the graph
        > taken from the manufacturer:
        > http://www.robot-electronics.co.uk/htm/sonar_faq.htm but Devantech really do
        > not give a clear figure for the beam width. I just see that depending on the
        > decibels the beam is wider on narrower. My though is that the transducer is
        > used at about -18dB and therefore the cone width is about 100 degrees.
        >
        > But I'm not sure I'm doing correctly or my unit is wrong in some way.
        >
        > Could someone please confirm from experience the beam width?
        >
        > Thanks a lot in advance
        >
        > Alejandro Alonso Puig
        > http://mundobot.com
        > alejandro.alonso@...
        >
        > -----Original Message-----
        > From: Doug Evans [mailto:DEvans@...]
        > Sent: sabado, 04 de octubre de 2003 0:55
        > To: Tom Capon; seattleRobotics@yahoogroups.com
        > Subject: RE: [SeattleRobotics] MPLAB error message
        >
        > you need a colon ':' character to define the label, if you are using MPASM.
        >
        > you should have
        >
        > KBD_1:
        >
        > not
        >
        > KBD_1
        >
        > -de
        >
        > -----Original Message-----
        > From: Tom Capon [mailto:robot@...]
        > Sent: Friday, October 03, 2003 4:32 PM
        > To: seattleRobotics@yahoogroups.com
        > Subject: Re: [SeattleRobotics] MPLAB error message
        >
        > Well, it gives errors from this code:
        >
        > goto KBD_1
        > bsf KBD,0x07
        > goto KBD_2
        > KBD_1 bcf KBD,0x07
        > KBD_2 decfsz ISRtmp1,W ; skip if ISRtmp1 == 1
        >
        > I think I will simply retype it or something and see what happends.
        >
        > At 08:22 AM 10/3/03 -0700, Jim McBride wrote:
        > >Make sure you don't have a case sensitive issue. In school I gave up and
        > >just coded everything in upper case to keep from getting bit.
        > >Have a look in your include file for your processor. You may find some
        > >answers there as well.
        > >Jim
        > >
        > >At 04:54 PM 10/2/2003 -0700, Scott Pierce wrote:
        > > >Then the GOTO statement probably points to a label which is not defined,
        > > >for example you could have a line that says: GOTO Delay; but Delay isn't
        > > >defined so the assembler doesn't know where you're trying to go to.
        > > >
        > > >Scott Pierce
        > > >
        > > >At 07:42 PM 10/2/2003 -0400, you wrote:
        > > > >Actually, it gives the "symbol not previously defined" error to GOTO
        > > > >statement line labels that are a few (or a lot) of lines down. I'll
        > > > >probably end up rewriting a bunch of it anyway, I'll come back if it
        > still
        > > > >doesn't work.
        > > >
        > > >
        > > >Visit the SRS Website at http://www.seattlerobotics.org
        > > >
        > > >To unsubscribe from this group, send an email to:
        > > >SeattleRobotics-unsubscribe@yahoogroups.com
        > > >
        > > >
        > > >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
        > >
        > >
        > >
        > >Visit the SRS Website at http://www.seattlerobotics.org
        > >
        > >To unsubscribe from this group, send an email to:
        > >SeattleRobotics-unsubscribe@yahoogroups.com
        > >
        > >
        > >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
        >
        > Visit the SRS Website at http://www.seattlerobotics.org
        >
        > To unsubscribe from this group, send an email to:
        > SeattleRobotics-unsubscribe@yahoogroups.com
        >
        > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
        >
        > Visit the SRS Website at http://www.seattlerobotics.org
        >
        > To unsubscribe from this group, send an email to:
        > SeattleRobotics-unsubscribe@yahoogroups.com
        >
        > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
        >
        > Visit the SRS Website at http://www.seattlerobotics.org
        >
        > To unsubscribe from this group, send an email to:
        > SeattleRobotics-unsubscribe@yahoogroups.com
        >
        >
        > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
      • dan michaels
        ... the angle ... what I m ... but in my ... degrees ... the graph ... really do ... depending on the ... transducer is ... degrees. ... way. ... Alonso, the
        Message 3 of 17 , Dec 1, 2003
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          --- In SeattleRobotics@yahoogroups.com, "Alejandro Alonso Puig"
          <alejandro.alonso@m...> wrote:
          >
          > Hi all,
          >
          > I've got a question. Does anyone of you know by experience what is
          the angle
          > of detection of the sonar ranger SRF08 from Devantech?.
          >
          > I have found some information on the Internet, but I don't believe
          what I'm
          > reading. I found that the angle detection is of about 40 degrees,
          but in my
          > tests I find it is about 100 degrees. SRF04 seems to really have 40
          degrees
          > of beam angle, but not SRF08.
          >
          > The most interesting information I found about the beam pattern is
          the graph
          > taken from the manufacturer:
          > http://www.robot-electronics.co.uk/htm/sonar_faq.htm but Devantech
          really do
          > not give a clear figure for the beam width. I just see that
          depending on the
          > decibels the beam is wider on narrower. My though is that the
          transducer is
          > used at about -18dB and therefore the cone width is about 100
          degrees.
          >
          > But I'm not sure I'm doing correctly or my unit is wrong in some
          way.
          >
          > Could someone please confirm from experience the beam width?
          >
          > Thanks a lot in advance
          >
          > Alejandro Alonso Puig
          > http://mundobot.com
          > alejandro.alonso@m...


          Alonso, the beam width you measure will no doubt depend upon both the
          size of your target, and also the distance away from the transducers.
          If you use a large target up close, it will be detected over a much
          wider angle than if you use a small target far away.

          If you take a look at the Acroname site, they show a slightly
          different way of representing beam pattern than the diagram on the
          robot-electronics site. It shows that a target 10 feet or more
          distance will be detected over about 45 deg total angle, but if it's
          only 2 feet distance then it will be detected over almost 90 deg.
          Then factor in the width of the target, and you will get a slightly
          larger angle, on top of this.

          http://acroname.com/robotics/parts/R145-SRF08.html


          - dan michaels
          www.oricomtech.com
          ============================
        • Karim Virani
          Is there any physical way to confine the angle further - without throwing off the results? I d like to reject everything outside of about 7 to 10 degrees from
          Message 4 of 17 , Dec 1, 2003
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            Is there any physical way to confine the angle further - without throwing off the results? I'd like to reject everything outside of about 7 to 10 degrees from center, 15 to 20 degree total cone.

            Karim



            -----Original Message-----
            From: dan michaels [mailto:dan@...]
            Sent: Monday, December 01, 2003 3:38 PM
            To: SeattleRobotics@yahoogroups.com
            Subject: [SeattleRobotics] Re: SRF08 beam angle


            --- In SeattleRobotics@yahoogroups.com, "Alejandro Alonso Puig"
            <alejandro.alonso@m...> wrote:
            >
            > Hi all,
            >
            > I've got a question. Does anyone of you know by experience what is
            the angle
            > of detection of the sonar ranger SRF08 from Devantech?.
            >
            > I have found some information on the Internet, but I don't believe
            what I'm
            > reading. I found that the angle detection is of about 40 degrees,
            but in my
            > tests I find it is about 100 degrees. SRF04 seems to really have 40
            degrees
            > of beam angle, but not SRF08.
            >
            > The most interesting information I found about the beam pattern is
            the graph
            > taken from the manufacturer:
            > http://www.robot-electronics.co.uk/htm/sonar_faq.htm but Devantech
            really do
            > not give a clear figure for the beam width. I just see that
            depending on the
            > decibels the beam is wider on narrower. My though is that the
            transducer is
            > used at about -18dB and therefore the cone width is about 100
            degrees.
            >
            > But I'm not sure I'm doing correctly or my unit is wrong in some
            way.
            >
            > Could someone please confirm from experience the beam width?
            >
            > Thanks a lot in advance
            >
            > Alejandro Alonso Puig
            > http://mundobot.com
            > alejandro.alonso@m...


            Alonso, the beam width you measure will no doubt depend upon both the
            size of your target, and also the distance away from the transducers.
            If you use a large target up close, it will be detected over a much
            wider angle than if you use a small target far away.

            If you take a look at the Acroname site, they show a slightly
            different way of representing beam pattern than the diagram on the
            robot-electronics site. It shows that a target 10 feet or more
            distance will be detected over about 45 deg total angle, but if it's
            only 2 feet distance then it will be detected over almost 90 deg.
            Then factor in the width of the target, and you will get a slightly
            larger angle, on top of this.

            http://acroname.com/robotics/parts/R145-SRF08.html


            - dan michaels
            www.oricomtech.com
            ============================


            Visit the SRS Website at http://www.seattlerobotics.org

            To unsubscribe from this group, send an email to:
            SeattleRobotics-unsubscribe@yahoogroups.com


            Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
          • Paul R. Lundgren
            The beam angle in usually related to the diameter of the radiating surface. The larger the diameter, the smaller the beam angle. For air you will need
            Message 5 of 17 , Dec 1, 2003
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              The beam angle in usually related to the diameter of the radiating surface. The larger the diameter, the smaller the beam angle. For air you will need something like 2: diameter or so. to get 30
              degrees total angle.

              Hagar

              Karim Virani wrote:

              > Is there any physical way to confine the angle further - without throwing off the results? I'd like to reject everything outside of about 7 to 10 degrees from center, 15 to 20 degree total cone.
              >
              > Karim
              >
              > -----Original Message-----
              > From: dan michaels [mailto:dan@...]
              > Sent: Monday, December 01, 2003 3:38 PM
              > To: SeattleRobotics@yahoogroups.com
              > Subject: [SeattleRobotics] Re: SRF08 beam angle
              >
              > --- In SeattleRobotics@yahoogroups.com, "Alejandro Alonso Puig"
              > <alejandro.alonso@m...> wrote:
              > >
              > > Hi all,
              > >
              > > I've got a question. Does anyone of you know by experience what is
              > the angle
              > > of detection of the sonar ranger SRF08 from Devantech?.
              > >
              > > I have found some information on the Internet, but I don't believe
              > what I'm
              > > reading. I found that the angle detection is of about 40 degrees,
              > but in my
              > > tests I find it is about 100 degrees. SRF04 seems to really have 40
              > degrees
              > > of beam angle, but not SRF08.
              > >
              > > The most interesting information I found about the beam pattern is
              > the graph
              > > taken from the manufacturer:
              > > http://www.robot-electronics.co.uk/htm/sonar_faq.htm but Devantech
              > really do
              > > not give a clear figure for the beam width. I just see that
              > depending on the
              > > decibels the beam is wider on narrower. My though is that the
              > transducer is
              > > used at about -18dB and therefore the cone width is about 100
              > degrees.
              > >
              > > But I'm not sure I'm doing correctly or my unit is wrong in some
              > way.
              > >
              > > Could someone please confirm from experience the beam width?
              > >
              > > Thanks a lot in advance
              > >
              > > Alejandro Alonso Puig
              > > http://mundobot.com
              > > alejandro.alonso@m...
              >
              > Alonso, the beam width you measure will no doubt depend upon both the
              > size of your target, and also the distance away from the transducers.
              > If you use a large target up close, it will be detected over a much
              > wider angle than if you use a small target far away.
              >
              > If you take a look at the Acroname site, they show a slightly
              > different way of representing beam pattern than the diagram on the
              > robot-electronics site. It shows that a target 10 feet or more
              > distance will be detected over about 45 deg total angle, but if it's
              > only 2 feet distance then it will be detected over almost 90 deg.
              > Then factor in the width of the target, and you will get a slightly
              > larger angle, on top of this.
              >
              > http://acroname.com/robotics/parts/R145-SRF08.html
              >
              > - dan michaels
              > www.oricomtech.com
              > ============================
              >
              > Visit the SRS Website at http://www.seattlerobotics.org
              >
              > To unsubscribe from this group, send an email to:
              > SeattleRobotics-unsubscribe@yahoogroups.com
              >
              >
              > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
              >
              > Visit the SRS Website at http://www.seattlerobotics.org
              >
              > To unsubscribe from this group, send an email to:
              > SeattleRobotics-unsubscribe@yahoogroups.com
              >
              >
              > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
            • Phil
              what about some sort of tuning pipe that you slip over the reciever to decrease the field of view that the receiver actually sees? sort of like blinders for
              Message 6 of 17 , Dec 1, 2003
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                what about some sort of tuning "pipe" that you slip over the reciever
                to decrease the field of view that the receiver actually sees? sort
                of like blinders for a horse...

                also, different Transceivers have different characteristics. I'm not
                sure you want to take on building your own but I know that there are
                several that have much narrower patterns. For example, the murata MA
                A1 series (75Khz) shows a significantly narrower pattern and they
                claim a 7 degree directivity (if that's really a word...).

                Phil

                --- In SeattleRobotics@yahoogroups.com, "Karim Virani" <karim@c...>
                wrote:
                > Is there any physical way to confine the angle further - without
                throwing off the results? I'd like to reject everything outside of
                about 7 to 10 degrees from center, 15 to 20 degree total cone.
                >
                > Karim
                >
                >
                >
                > -----Original Message-----
                > From: dan michaels [mailto:dan@o...]
                > Sent: Monday, December 01, 2003 3:38 PM
                > To: SeattleRobotics@yahoogroups.com
                > Subject: [SeattleRobotics] Re: SRF08 beam angle
                >
                >
                > --- In SeattleRobotics@yahoogroups.com, "Alejandro Alonso Puig"
                > <alejandro.alonso@m...> wrote:
                > >
                > > Hi all,
                > >
                > > I've got a question. Does anyone of you know by experience what
                is
                > the angle
                > > of detection of the sonar ranger SRF08 from Devantech?.
                > >
                > > I have found some information on the Internet, but I don't
                believe
                > what I'm
                > > reading. I found that the angle detection is of about 40 degrees,
                > but in my
                > > tests I find it is about 100 degrees. SRF04 seems to really have
                40
                > degrees
                > > of beam angle, but not SRF08.
                > >
                > > The most interesting information I found about the beam pattern
                is
                > the graph
                > > taken from the manufacturer:
                > > http://www.robot-electronics.co.uk/htm/sonar_faq.htm but
                Devantech
                > really do
                > > not give a clear figure for the beam width. I just see that
                > depending on the
                > > decibels the beam is wider on narrower. My though is that the
                > transducer is
                > > used at about -18dB and therefore the cone width is about 100
                > degrees.
                > >
                > > But I'm not sure I'm doing correctly or my unit is wrong in some
                > way.
                > >
                > > Could someone please confirm from experience the beam width?
                > >
                > > Thanks a lot in advance
                > >
                > > Alejandro Alonso Puig
                > > http://mundobot.com
                > > alejandro.alonso@m...
                >
                >
                > Alonso, the beam width you measure will no doubt depend upon both
                the
                > size of your target, and also the distance away from the
                transducers.
                > If you use a large target up close, it will be detected over a much
                > wider angle than if you use a small target far away.
                >
                > If you take a look at the Acroname site, they show a slightly
                > different way of representing beam pattern than the diagram on the
                > robot-electronics site. It shows that a target 10 feet or more
                > distance will be detected over about 45 deg total angle, but if
                it's
                > only 2 feet distance then it will be detected over almost 90 deg.
                > Then factor in the width of the target, and you will get a slightly
                > larger angle, on top of this.
                >
                > http://acroname.com/robotics/parts/R145-SRF08.html
                >
                >
                > - dan michaels
                > www.oricomtech.com
                > ============================
                >
                >
                > Visit the SRS Website at http://www.seattlerobotics.org
                >
                > To unsubscribe from this group, send an email to:
                > SeattleRobotics-unsubscribe@yahoogroups.com
                >
                >
                > Your use of Yahoo! Groups is subject to
                http://docs.yahoo.com/info/terms/
              • dan michaels
                ... reciever ... sort ... I was thinking about the same sort of thing, but I really haven t much idea how to do it. Sound works differently from light. Sound
                Message 7 of 17 , Dec 1, 2003
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                  --- In SeattleRobotics@yahoogroups.com, "Phil" <phil1960us@y...>
                  wrote:
                  > what about some sort of tuning "pipe" that you slip over the
                  reciever
                  > to decrease the field of view that the receiver actually sees?
                  sort
                  > of like blinders for a horse...


                  I was thinking about the same sort of thing, but I really haven't
                  much idea how to do it. Sound works differently from light. Sound can
                  go around corners, etc. Something to try might be tubes of rolled
                  cardboard/plastic/etc around the transmitter with lengths at "odd"
                  multiples of "quarter" wavelength. At even multiples, I think the
                  sound pressure will be a minimum, but I'm not really sure about this
                  stuff at all. Or possibly a megaphone/conical horn - but again it
                  probably needs the correct length and end aperture size for best
                  results. Good area for experimentation - plus some preliminary
                  legwork into acoustics. Tell us how it goes ;-).


                  - dan michaels
                  www.oricomtech.com
                  ============================
                • LJGeib@aol.com
                  The other thing you can do, (besides a larger aperture), is to decrease the wavelength(increase the frequency) of the sound waves. That s the difference
                  Message 8 of 17 , Dec 1, 2003
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                    The other thing you can do, (besides a larger aperture), is to decrease the
                    wavelength(increase the frequency) of the sound waves. That's the difference
                    between detection and target acquisition radar and sonar.

                    Larry

                    In a message dated 12/1/03 6:09:44 PM Pacific Standard Time, Hagar@...
                    writes:
                    The beam angle in usually related to the diameter of the radiating surface.
                    The larger the diameter, the smaller the beam angle. For air you will need
                    something like 2: diameter or so. to get 30
                    degrees total angle.

                    Hagar


                    [Non-text portions of this message have been removed]
                  • RoboVac
                    The ones I have seen on commercial products were parabolas instead of cones. They typically were very long compared to the diameter. William Crolley ... From:
                    Message 9 of 17 , Dec 1, 2003
                    • 0 Attachment
                      The ones I have seen on commercial products were parabolas instead of cones.
                      They typically were very long compared to the diameter.

                      William Crolley

                      ----- Original Message -----
                      From: "dan michaels" <dan@...>
                      To: <SeattleRobotics@yahoogroups.com>
                      Sent: Monday, December 01, 2003 8:47 PM
                      Subject: [SeattleRobotics] Re: SRF08 beam angle


                      > --- In SeattleRobotics@yahoogroups.com, "Phil" <phil1960us@y...>
                      > wrote:
                      > > what about some sort of tuning "pipe" that you slip over the
                      > reciever
                      > > to decrease the field of view that the receiver actually sees?
                      > sort
                      > > of like blinders for a horse...
                      >
                      >
                      > I was thinking about the same sort of thing, but I really haven't
                      > much idea how to do it. Sound works differently from light. Sound can
                      > go around corners, etc. Something to try might be tubes of rolled
                      > cardboard/plastic/etc around the transmitter with lengths at "odd"
                      > multiples of "quarter" wavelength. At even multiples, I think the
                      > sound pressure will be a minimum, but I'm not really sure about this
                      > stuff at all. Or possibly a megaphone/conical horn - but again it
                      > probably needs the correct length and end aperture size for best
                      > results. Good area for experimentation - plus some preliminary
                      > legwork into acoustics. Tell us how it goes ;-).
                      >
                      >
                      > - dan michaels
                      > www.oricomtech.com
                      > ============================
                      >
                      >
                      >
                      > Visit the SRS Website at http://www.seattlerobotics.org
                      >
                      > To unsubscribe from this group, send an email to:
                      > SeattleRobotics-unsubscribe@yahoogroups.com
                      >
                      >
                      > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                      >
                      >
                    • LJGeib@aol.com
                      Having two or more receivers measuring the return from the same radiator would give a sort of inerferometry aperture synthesis. Mark Medonis demonstrated a
                      Message 10 of 17 , Dec 2, 2003
                      • 0 Attachment
                        Having two or more receivers measuring the return from the same radiator
                        would give a sort of inerferometry aperture synthesis. Mark Medonis demonstrated
                        a tracking system he designed for Maxwell, his robot head.His tracked a
                        modulated beacon and measured phase shift., but you could use is with a point
                        source radiated by the robot, too.
                        The more receivers, the larger the central spike(s) and the smaller the side
                        lobes would be, and the receivers should be spaced with relation to the
                        radiated frequency(typically something like 1/4 wavelength spacing.)

                        You could even do phase compensation in software to get real aperture
                        systhesis. though this might take too much time to build an image over several pings.


                        Models to look at: the Very Large Array radio teelescope. the Keck Telescope
                        Observatory.

                        Larry


                        In a message dated 12/1/03 6:09:44 PM Pacific Standard Time, Hagar@...
                        writes:
                        The beam angle in usually related to the diameter of the radiating surface.
                        The larger the diameter, the smaller the beam angle. For air you will need
                        something like 2: diameter or so. to get 30
                        degrees total angle.

                        Hagar


                        [Non-text portions of this message have been removed]
                      • warrenhb
                        ... You could imagine trying to cut the beam width by putting something in the way. Since there is a separate emitter and detector, you might be able to absorb
                        Message 11 of 17 , Dec 2, 2003
                        • 0 Attachment
                          From http://www.robot-electronics.co.uk/htm/sonar_faq.htm:
                          | Q. How can I narrow the beam width?
                          | A. You can't! This is a question which crops up regularly, however there
                          | is no easy way to reduce or change the beam width that I'm aware of. The
                          | beam pattern of the SRF04/8 is conical with the width of the beam being a
                          | function of the surface area of the transducers and is fixed. The beam
                          | pattern of the transducers used on the SRF04/8, taken from the
                          | manufacturers data sheet, is shown below.

                          You could imagine trying to cut the beam width by putting something
                          in the way. Since there is a separate emitter and detector, you might be
                          able to absorb or deflect part of the outgoing beam away from the path
                          to the detector, or shield the detector so it would detect a narrower angle.
                          This probably wouldn't work because of diffraction - you end up making
                          a smaller emitter, but it acts as a point source, like dropping a rock in a
                          pool of water, which could produce an even wider beam. Shielding the
                          detector could produce the same result, for the same reason a radio
                          antenna has a similar pattern for transmit and receive.

                          Thinking about how you improve the directivity of a radio antenna, you
                          might be able to make a phased array of emitters and/or detectors, but
                          that sounds expensive and would require redesigning the circuitry to
                          work with multiple transducers. How about a parabolic dish? That
                          sounds doable! There's a calculation that should tell you how much
                          improvement in directivity you would get due to a dish a given number
                          of wavelengths in diameter. I don't know it off hand, but you might be
                          able to search for it on-line. If you find the version for microwaves, you
                          could substitute the speed of sound for the speed of light to convert it
                          to ultrasonics. If you don't find the calculation on-line, try the ARRL
                          handbook.

                          You could put a dish on either the emitter, the detector, or both. Putting
                          a dish on the emitter would improve the signal strength; putting one on
                          the detector would improve the immunity to other emitters. You might
                          be able to mount the pair at the focus of a single large dish - that way
                          you wouldn't have to take the unit apart. This would be pretty easy to
                          test! Get a Big Ear or similar dish-based microphone, or look for a
                          suitable kitchen dish or barbeque lid, etc. Anything roughly
                          hemispherical should be close enough to parabolic to produce some
                          improvement.

                          However, a dish could make your robot a lot larger. There might be a
                          way to make an ultrasonic lens, but the dish sounds easier to do with
                          readily available materials. To make a lens, you need to find a material
                          for which the speed of sound is different from the speed in air, that
                          is transparent to the sound. If the speed of sound is faster, you would
                          make a concave lens to focus the beam; if the speed of sound is slower,
                          you would make a convex lens. To get an idea of how much smaller this
                          could be than an equivalent dish, consider the new lens-based headlights
                          compared to the traditional sealed-beam headlights.

                          By the way, an old headlight reflector might be a good dish to try. Either
                          trim the front off a dead sealed-beam headlight, or go to a junk yard and
                          get the reflector from one of the newer "European style" headlights that
                          are not sealed-beam.

                          Doug Bell

                          ----- Original Message -----
                          From: "Karim Virani" <karim@...>
                          To: <SeattleRobotics@yahoogroups.com>
                          Sent: Monday, December 01, 2003 2:55 PM
                          Subject: RE: [SeattleRobotics] Re: SRF08 beam angle


                          | Is there any physical way to confine the angle further - without throwing
                          off the results? I'd like to reject everything outside of about 7 to 10
                          degrees from center, 15 to 20 degree total cone.
                          |
                          | Karim
                        • Alejandro Alonso Puig
                          Really interesting answers. Thanks. Dan, the graph from Acroname is really clear. I ll make some tests during this weekend but it seems that the tests I
                          Message 12 of 17 , Dec 2, 2003
                          • 0 Attachment
                            Really interesting answers. Thanks. Dan, the graph from Acroname is really
                            clear. I'll make some tests during this weekend but it seems that the tests
                            I performed more or less agree with the graph. The measures were taken at 1
                            meter from the transducer. That is 3,28 feet and as from the graph, the
                            width at such distance is of about 80 degrees (not so far from the 100
                            degrees I measured, considering I'm not testing in an ideal environment).

                            In any case I think it is very wide if we really want to have some clear
                            information on the surroundings. As per trigonometry
                            (Arc=angleº(pi/180)Distance), the chord (arc) detected at 1 meter from the
                            transducer is Arc=80º(pi/180)1= 1,4 meters. That means 0,7m to the right,
                            0,7m to the left, 0,7m to the top and 0,7m to the bottom. If I'm not
                            mistaken, this means that if you want to detect something at a distance of 1
                            meter from your robot, the transducer should be either installed at least
                            0,7m from the floor and in 90º position, or install it in a lower position
                            but with a vertical inclination greater than 90º, so you will not detect the
                            floor (kind of reflecting floor), but you will detect things over the robot
                            (may be a problem in some cases)

                            If I am right with this assertions, the SRF08 is good because of the I2C
                            interface, but not so good because of the beam width.

                            I read something about putting some kind of foam around the transducer to
                            force a reduction on the detection cone. I'm not sure if it will work, but
                            I'll try it during the weekend. I'll tell you.

                            By the way, I raised the question to Devantech Company and the answer I got
                            was: "Beam width on the SRF04/8 is a function of the transducers and is
                            fixed. For the transducers used on the SRF04/8 this is 55 degrees at
                            the -6db point". Not as interesting as your answers.

                            Best regards

                            Alejandro Alonso Puig
                            http://mundobot.com
                            alejandro.alonso@...




                            -----Original Message-----
                            From: dan michaels [mailto:dan@...]
                            Sent: martes, 02 de diciembre de 2003 3:48
                            To: SeattleRobotics@yahoogroups.com
                            Subject: [SeattleRobotics] Re: SRF08 beam angle


                            --- In SeattleRobotics@yahoogroups.com, "Phil" <phil1960us@y...>
                            wrote:
                            > what about some sort of tuning "pipe" that you slip over the
                            reciever
                            > to decrease the field of view that the receiver actually sees?
                            sort
                            > of like blinders for a horse...


                            I was thinking about the same sort of thing, but I really haven't
                            much idea how to do it. Sound works differently from light. Sound can
                            go around corners, etc. Something to try might be tubes of rolled
                            cardboard/plastic/etc around the transmitter with lengths at "odd"
                            multiples of "quarter" wavelength. At even multiples, I think the
                            sound pressure will be a minimum, but I'm not really sure about this
                            stuff at all. Or possibly a megaphone/conical horn - but again it
                            probably needs the correct length and end aperture size for best
                            results. Good area for experimentation - plus some preliminary
                            legwork into acoustics. Tell us how it goes ;-).


                            - dan michaels
                            www.oricomtech.com
                            ============================



                            Visit the SRS Website at http://www.seattlerobotics.org

                            To unsubscribe from this group, send an email to:
                            SeattleRobotics-unsubscribe@yahoogroups.com


                            Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                          • dan michaels
                            ... wrote: You might also check out the following page, which shows a sweep using such a sonar. The image shows extended widths of
                            Message 13 of 17 , Dec 2, 2003
                            • 0 Attachment
                              --- In SeattleRobotics@yahoogroups.com, "Alejandro Alonso Puig"
                              <alejandro.alonso@m...> wrote:

                              You might also check out the following page, which shows a sweep
                              using such a sonar. The "image" shows extended widths of objects in
                              azimuth.

                              http://www.hazmat.com/~mjb/projects/picsonar/

                              I had often wondered about the idea of doing an inverse spatial
                              convolution on such an image in order to try and remove the beam
                              width characteristic. This might be a lot of processing for a small
                              microcontroller.

                              - dan michaels
                              ======================


                              > Really interesting answers. Thanks. Dan, the graph from Acroname is
                              really
                              > clear. I'll make some tests during this weekend but it seems that
                              the tests
                              > I performed more or less agree with the graph. The measures were
                              taken at 1
                              > meter from the transducer. That is 3,28 feet and as from the
                              graph, the
                              > width at such distance is of about 80 degrees (not so far from the
                              100
                              > degrees I measured, considering I'm not testing in an ideal
                              environment).
                              >
                              > In any case I think it is very wide if we really want to have some
                              clear
                              > information on the surroundings. As per trigonometry
                              > (Arc=angleº(pi/180)Distance), the chord (arc) detected at 1 meter
                              from the
                              > transducer is Arc=80º(pi/180)1= 1,4 meters. That means 0,7m to the
                              right,
                              > 0,7m to the left, 0,7m to the top and 0,7m to the bottom. If I'm not
                              > mistaken, this means that if you want to detect something at a
                              distance of 1
                              > meter from your robot, the transducer should be either installed at
                              least
                              > 0,7m from the floor and in 90º position, or install it in a lower
                              position
                              > but with a vertical inclination greater than 90º, so you will not
                              detect the
                              > floor (kind of reflecting floor), but you will detect things over
                              the robot
                              > (may be a problem in some cases)
                              >
                              > If I am right with this assertions, the SRF08 is good because of
                              the I2C
                              > interface, but not so good because of the beam width.
                              >
                              > I read something about putting some kind of foam around the
                              transducer to
                              > force a reduction on the detection cone. I'm not sure if it will
                              work, but
                              > I'll try it during the weekend. I'll tell you.
                              >
                              > By the way, I raised the question to Devantech Company and the
                              answer I got
                              > was: "Beam width on the SRF04/8 is a function of the transducers
                              and is
                              > fixed. For the transducers used on the SRF04/8 this is 55 degrees at
                              > the -6db point". Not as interesting as your answers.
                              >
                              > Best regards
                              >
                              > Alejandro Alonso Puig
                              > http://mundobot.com
                              > alejandro.alonso@m...
                              >
                              >
                              >
                              >
                              > -----Original Message-----
                              > From: dan michaels [mailto:dan@o...]
                              > Sent: martes, 02 de diciembre de 2003 3:48
                              > To: SeattleRobotics@yahoogroups.com
                              > Subject: [SeattleRobotics] Re: SRF08 beam angle
                              >
                              >
                              > --- In SeattleRobotics@yahoogroups.com, "Phil" <phil1960us@y...>
                              > wrote:
                              > > what about some sort of tuning "pipe" that you slip over the
                              > reciever
                              > > to decrease the field of view that the receiver actually sees?
                              > sort
                              > > of like blinders for a horse...
                              >
                              >
                              > I was thinking about the same sort of thing, but I really haven't
                              > much idea how to do it. Sound works differently from light. Sound
                              can
                              > go around corners, etc. Something to try might be tubes of rolled
                              > cardboard/plastic/etc around the transmitter with lengths at "odd"
                              > multiples of "quarter" wavelength. At even multiples, I think the
                              > sound pressure will be a minimum, but I'm not really sure about this
                              > stuff at all. Or possibly a megaphone/conical horn - but again it
                              > probably needs the correct length and end aperture size for best
                              > results. Good area for experimentation - plus some preliminary
                              > legwork into acoustics. Tell us how it goes ;-).
                              >
                              >
                              > - dan michaels
                              > www.oricomtech.com
                              > ============================
                              >
                              >
                              >
                              > Visit the SRS Website at http://www.seattlerobotics.org
                              >
                              > To unsubscribe from this group, send an email to:
                              > SeattleRobotics-unsubscribe@yahoogroups.com
                              >
                              >
                              > Your use of Yahoo! Groups is subject to
                              http://docs.yahoo.com/info/terms/
                            • Alejandro Alonso Puig
                              Yes, I thought the same as you, eliminating the width in the image in order to narrow the figures to its real form. I saw this article. In fact I m working in
                              Message 14 of 17 , Dec 2, 2003
                              • 0 Attachment
                                Yes, I thought the same as you, eliminating the width in the image in order
                                to narrow the figures to its real form. I saw this article. In fact I'm
                                working in something similar. Look at my web page site. Its in Spanish yet,
                                but I'll treanslate to English soon. The page is not finished, but at least
                                you will find a figure that represents what I'm doing with the sonar
                                ranger(Hardware and Software): http://mundobot.com/tecnica/Sonar/Sonar.htm

                                Best regards

                                Alejandro Alonso Puig
                                http://mundobot.com
                                alejandro.alonso@...




                                -----Original Message-----
                                From: dan michaels [mailto:dan@...]
                                Sent: martes, 02 de diciembre de 2003 17:24
                                To: SeattleRobotics@yahoogroups.com
                                Subject: [SeattleRobotics] Re: SRF08 beam angle


                                --- In SeattleRobotics@yahoogroups.com, "Alejandro Alonso Puig"
                                <alejandro.alonso@m...> wrote:

                                You might also check out the following page, which shows a sweep
                                using such a sonar. The "image" shows extended widths of objects in
                                azimuth.

                                http://www.hazmat.com/~mjb/projects/picsonar/

                                I had often wondered about the idea of doing an inverse spatial
                                convolution on such an image in order to try and remove the beam
                                width characteristic. This might be a lot of processing for a small
                                microcontroller.

                                - dan michaels
                                ======================


                                > Really interesting answers. Thanks. Dan, the graph from Acroname is
                                really
                                > clear. I'll make some tests during this weekend but it seems that
                                the tests
                                > I performed more or less agree with the graph. The measures were
                                taken at 1
                                > meter from the transducer. That is 3,28 feet and as from the
                                graph, the
                                > width at such distance is of about 80 degrees (not so far from the
                                100
                                > degrees I measured, considering I'm not testing in an ideal
                                environment).
                                >
                                > In any case I think it is very wide if we really want to have some
                                clear
                                > information on the surroundings. As per trigonometry
                                > (Arc=angleº(pi/180)Distance), the chord (arc) detected at 1 meter
                                from the
                                > transducer is Arc=80º(pi/180)1= 1,4 meters. That means 0,7m to the
                                right,
                                > 0,7m to the left, 0,7m to the top and 0,7m to the bottom. If I'm not
                                > mistaken, this means that if you want to detect something at a
                                distance of 1
                                > meter from your robot, the transducer should be either installed at
                                least
                                > 0,7m from the floor and in 90º position, or install it in a lower
                                position
                                > but with a vertical inclination greater than 90º, so you will not
                                detect the
                                > floor (kind of reflecting floor), but you will detect things over
                                the robot
                                > (may be a problem in some cases)
                                >
                                > If I am right with this assertions, the SRF08 is good because of
                                the I2C
                                > interface, but not so good because of the beam width.
                                >
                                > I read something about putting some kind of foam around the
                                transducer to
                                > force a reduction on the detection cone. I'm not sure if it will
                                work, but
                                > I'll try it during the weekend. I'll tell you.
                                >
                                > By the way, I raised the question to Devantech Company and the
                                answer I got
                                > was: "Beam width on the SRF04/8 is a function of the transducers
                                and is
                                > fixed. For the transducers used on the SRF04/8 this is 55 degrees at
                                > the -6db point". Not as interesting as your answers.
                                >
                                > Best regards
                                >
                                > Alejandro Alonso Puig
                                > http://mundobot.com
                                > alejandro.alonso@m...
                                >
                                >
                                >
                                >
                                > -----Original Message-----
                                > From: dan michaels [mailto:dan@o...]
                                > Sent: martes, 02 de diciembre de 2003 3:48
                                > To: SeattleRobotics@yahoogroups.com
                                > Subject: [SeattleRobotics] Re: SRF08 beam angle
                                >
                                >
                                > --- In SeattleRobotics@yahoogroups.com, "Phil" <phil1960us@y...>
                                > wrote:
                                > > what about some sort of tuning "pipe" that you slip over the
                                > reciever
                                > > to decrease the field of view that the receiver actually sees?
                                > sort
                                > > of like blinders for a horse...
                                >
                                >
                                > I was thinking about the same sort of thing, but I really haven't
                                > much idea how to do it. Sound works differently from light. Sound
                                can
                                > go around corners, etc. Something to try might be tubes of rolled
                                > cardboard/plastic/etc around the transmitter with lengths at "odd"
                                > multiples of "quarter" wavelength. At even multiples, I think the
                                > sound pressure will be a minimum, but I'm not really sure about this
                                > stuff at all. Or possibly a megaphone/conical horn - but again it
                                > probably needs the correct length and end aperture size for best
                                > results. Good area for experimentation - plus some preliminary
                                > legwork into acoustics. Tell us how it goes ;-).
                                >
                                >
                                > - dan michaels
                                > www.oricomtech.com
                                > ============================
                                >
                                >
                                >
                                > Visit the SRS Website at http://www.seattlerobotics.org
                                >
                                > To unsubscribe from this group, send an email to:
                                > SeattleRobotics-unsubscribe@yahoogroups.com
                                >
                                >
                                > Your use of Yahoo! Groups is subject to
                                http://docs.yahoo.com/info/terms/


                                Visit the SRS Website at http://www.seattlerobotics.org

                                To unsubscribe from this group, send an email to:
                                SeattleRobotics-unsubscribe@yahoogroups.com


                                Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                              • Alejandro Alonso Puig
                                As promised, here you have the results of my testing with the SRF08 sonar ranger during the weekend (monday was also holiday at Madrid/Spain :-) 1) The SRF08
                                Message 15 of 17 , Dec 9, 2003
                                • 0 Attachment
                                  As promised, here you have the results of my testing with the SRF08 sonar
                                  ranger during the weekend (monday was also holiday at Madrid/Spain :-)

                                  1) The SRF08 follow more or less the beam pattern at
                                  http://acroname.com/robotics/parts/R145-SRF08.html
                                  2) The beam could be forced to be narrower by putting some foam around. I
                                  have reduced it 20 degrees max. If it is used excessive foam surface or try
                                  to narrow too much the beam, the results are unpredictable. Sometimes the
                                  transducer detect the foam and sometimes it does not detect even the
                                  obstacles just in front. In any case, by this trick it is possible to
                                  prevent detecting the floor when we do not want it.

                                  I have finished a technical document on a sonar ranger to understand how
                                  sonar rangers "see" the surroundings. Unfortunately it is in Spanish, but
                                  there are several figures that could help understanding. Also there are
                                  several links in English at the bottom of the page:
                                  http://mundobot.com/tecnica/Sonar/Sonar.htm

                                  Whenever I have enough time I'll translate my webpage to English

                                  Best regards,
                                  Alejandro Alonso Puig
                                  http://mundobot.com
                                  alejandro.alonso@...




                                  -----Original Message-----
                                  From: Alejandro Alonso Puig [mailto:alejandro.alonso@...]
                                  Sent: martes, 02 de diciembre de 2003 17:52
                                  To: SeattleRobotics@yahoogroups.com
                                  Subject: RE: [SeattleRobotics] Re: SRF08 beam angle


                                  Yes, I thought the same as you, eliminating the width in the image in order
                                  to narrow the figures to its real form. I saw this article. In fact I'm
                                  working in something similar. Look at my web page site. Its in Spanish yet,
                                  but I'll treanslate to English soon. The page is not finished, but at least
                                  you will find a figure that represents what I'm doing with the sonar
                                  ranger(Hardware and Software): http://mundobot.com/tecnica/Sonar/Sonar.htm

                                  Best regards

                                  Alejandro Alonso Puig
                                  http://mundobot.com
                                  alejandro.alonso@...




                                  -----Original Message-----
                                  From: dan michaels [mailto:dan@...]
                                  Sent: martes, 02 de diciembre de 2003 17:24
                                  To: SeattleRobotics@yahoogroups.com
                                  Subject: [SeattleRobotics] Re: SRF08 beam angle


                                  --- In SeattleRobotics@yahoogroups.com, "Alejandro Alonso Puig"
                                  <alejandro.alonso@m...> wrote:

                                  You might also check out the following page, which shows a sweep
                                  using such a sonar. The "image" shows extended widths of objects in
                                  azimuth.

                                  http://www.hazmat.com/~mjb/projects/picsonar/

                                  I had often wondered about the idea of doing an inverse spatial
                                  convolution on such an image in order to try and remove the beam
                                  width characteristic. This might be a lot of processing for a small
                                  microcontroller.

                                  - dan michaels
                                  ======================


                                  > Really interesting answers. Thanks. Dan, the graph from Acroname is
                                  really
                                  > clear. I'll make some tests during this weekend but it seems that
                                  the tests
                                  > I performed more or less agree with the graph. The measures were
                                  taken at 1
                                  > meter from the transducer. That is 3,28 feet and as from the
                                  graph, the
                                  > width at such distance is of about 80 degrees (not so far from the
                                  100
                                  > degrees I measured, considering I'm not testing in an ideal
                                  environment).
                                  >
                                  > In any case I think it is very wide if we really want to have some
                                  clear
                                  > information on the surroundings. As per trigonometry
                                  > (Arc=angleº(pi/180)Distance), the chord (arc) detected at 1 meter
                                  from the
                                  > transducer is Arc=80º(pi/180)1= 1,4 meters. That means 0,7m to the
                                  right,
                                  > 0,7m to the left, 0,7m to the top and 0,7m to the bottom. If I'm not
                                  > mistaken, this means that if you want to detect something at a
                                  distance of 1
                                  > meter from your robot, the transducer should be either installed at
                                  least
                                  > 0,7m from the floor and in 90º position, or install it in a lower
                                  position
                                  > but with a vertical inclination greater than 90º, so you will not
                                  detect the
                                  > floor (kind of reflecting floor), but you will detect things over
                                  the robot
                                  > (may be a problem in some cases)
                                  >
                                  > If I am right with this assertions, the SRF08 is good because of
                                  the I2C
                                  > interface, but not so good because of the beam width.
                                  >
                                  > I read something about putting some kind of foam around the
                                  transducer to
                                  > force a reduction on the detection cone. I'm not sure if it will
                                  work, but
                                  > I'll try it during the weekend. I'll tell you.
                                  >
                                  > By the way, I raised the question to Devantech Company and the
                                  answer I got
                                  > was: "Beam width on the SRF04/8 is a function of the transducers
                                  and is
                                  > fixed. For the transducers used on the SRF04/8 this is 55 degrees at
                                  > the -6db point". Not as interesting as your answers.
                                  >
                                  > Best regards
                                  >
                                  > Alejandro Alonso Puig
                                  > http://mundobot.com
                                  > alejandro.alonso@m...
                                  >
                                  >
                                  >
                                  >
                                  > -----Original Message-----
                                  > From: dan michaels [mailto:dan@o...]
                                  > Sent: martes, 02 de diciembre de 2003 3:48
                                  > To: SeattleRobotics@yahoogroups.com
                                  > Subject: [SeattleRobotics] Re: SRF08 beam angle
                                  >
                                  >
                                  > --- In SeattleRobotics@yahoogroups.com, "Phil" <phil1960us@y...>
                                  > wrote:
                                  > > what about some sort of tuning "pipe" that you slip over the
                                  > reciever
                                  > > to decrease the field of view that the receiver actually sees?
                                  > sort
                                  > > of like blinders for a horse...
                                  >
                                  >
                                  > I was thinking about the same sort of thing, but I really haven't
                                  > much idea how to do it. Sound works differently from light. Sound
                                  can
                                  > go around corners, etc. Something to try might be tubes of rolled
                                  > cardboard/plastic/etc around the transmitter with lengths at "odd"
                                  > multiples of "quarter" wavelength. At even multiples, I think the
                                  > sound pressure will be a minimum, but I'm not really sure about this
                                  > stuff at all. Or possibly a megaphone/conical horn - but again it
                                  > probably needs the correct length and end aperture size for best
                                  > results. Good area for experimentation - plus some preliminary
                                  > legwork into acoustics. Tell us how it goes ;-).
                                  >
                                  >
                                  > - dan michaels
                                  > www.oricomtech.com
                                  > ============================
                                  >
                                  >
                                  >
                                  > Visit the SRS Website at http://www.seattlerobotics.org
                                  >
                                  > To unsubscribe from this group, send an email to:
                                  > SeattleRobotics-unsubscribe@yahoogroups.com
                                  >
                                  >
                                  > Your use of Yahoo! Groups is subject to
                                  http://docs.yahoo.com/info/terms/


                                  Visit the SRS Website at http://www.seattlerobotics.org

                                  To unsubscribe from this group, send an email to:
                                  SeattleRobotics-unsubscribe@yahoogroups.com


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                                • Paul R. Lundgren
                                  You might want to read chapter 10 :Sound Field Characteristics in Relation to Ultrasonic Transducers of Yoshimitsu Kikuchi s book Ultrasonic Transducers ,
                                  Message 16 of 17 , Dec 9, 2003
                                  • 0 Attachment
                                    You might want to read chapter 10 :Sound Field Characteristics in Relation to Ultrasonic Transducers" of Yoshimitsu Kikuchi's book "Ultrasonic Transducers", published by
                                    Corona Publishing Co, Ltd, Tokyo, 1969. I found a English copy though my local (USA) library coop program.

                                    Hagar

                                    Alejandro Alonso Puig wrote:

                                    > As promised, here you have the results of my testing with the SRF08 sonar
                                    > ranger during the weekend (monday was also holiday at Madrid/Spain :-)
                                    >
                                    > 1) The SRF08 follow more or less the beam pattern at
                                    > http://acroname.com/robotics/parts/R145-SRF08.html
                                    > 2) The beam could be forced to be narrower by putting some foam around. I
                                    > have reduced it 20 degrees max. If it is used excessive foam surface or try
                                    > to narrow too much the beam, the results are unpredictable. Sometimes the
                                    > transducer detect the foam and sometimes it does not detect even the
                                    > obstacles just in front. In any case, by this trick it is possible to
                                    > prevent detecting the floor when we do not want it.
                                    >
                                    > I have finished a technical document on a sonar ranger to understand how
                                    > sonar rangers "see" the surroundings. Unfortunately it is in Spanish, but
                                    > there are several figures that could help understanding. Also there are
                                    > several links in English at the bottom of the page:
                                    > http://mundobot.com/tecnica/Sonar/Sonar.htm
                                    >
                                    > Whenever I have enough time I'll translate my webpage to English
                                    >
                                    > Best regards,
                                    > Alejandro Alonso Puig
                                    > http://mundobot.com
                                    > alejandro.alonso@...
                                    >
                                    > -----Original Message-----
                                    > From: Alejandro Alonso Puig [mailto:alejandro.alonso@...]
                                    > Sent: martes, 02 de diciembre de 2003 17:52
                                    > To: SeattleRobotics@yahoogroups.com
                                    > Subject: RE: [SeattleRobotics] Re: SRF08 beam angle
                                    >
                                    > Yes, I thought the same as you, eliminating the width in the image in order
                                    > to narrow the figures to its real form. I saw this article. In fact I'm
                                    > working in something similar. Look at my web page site. Its in Spanish yet,
                                    > but I'll treanslate to English soon. The page is not finished, but at least
                                    > you will find a figure that represents what I'm doing with the sonar
                                    > ranger(Hardware and Software): http://mundobot.com/tecnica/Sonar/Sonar.htm
                                    >
                                    > Best regards
                                    >
                                    > Alejandro Alonso Puig
                                    > http://mundobot.com
                                    > alejandro.alonso@...
                                    >
                                    > -----Original Message-----
                                    > From: dan michaels [mailto:dan@...]
                                    > Sent: martes, 02 de diciembre de 2003 17:24
                                    > To: SeattleRobotics@yahoogroups.com
                                    > Subject: [SeattleRobotics] Re: SRF08 beam angle
                                    >
                                    > --- In SeattleRobotics@yahoogroups.com, "Alejandro Alonso Puig"
                                    > <alejandro.alonso@m...> wrote:
                                    >
                                    > You might also check out the following page, which shows a sweep
                                    > using such a sonar. The "image" shows extended widths of objects in
                                    > azimuth.
                                    >
                                    > http://www.hazmat.com/~mjb/projects/picsonar/
                                    >
                                    > I had often wondered about the idea of doing an inverse spatial
                                    > convolution on such an image in order to try and remove the beam
                                    > width characteristic. This might be a lot of processing for a small
                                    > microcontroller.
                                    >
                                    > - dan michaels
                                    > ======================
                                    >
                                    > > Really interesting answers. Thanks. Dan, the graph from Acroname is
                                    > really
                                    > > clear. I'll make some tests during this weekend but it seems that
                                    > the tests
                                    > > I performed more or less agree with the graph. The measures were
                                    > taken at 1
                                    > > meter from the transducer. That is 3,28 feet and as from the
                                    > graph, the
                                    > > width at such distance is of about 80 degrees (not so far from the
                                    > 100
                                    > > degrees I measured, considering I'm not testing in an ideal
                                    > environment).
                                    > >
                                    > > In any case I think it is very wide if we really want to have some
                                    > clear
                                    > > information on the surroundings. As per trigonometry
                                    > > (Arc=angleº(pi/180)Distance), the chord (arc) detected at 1 meter
                                    > from the
                                    > > transducer is Arc=80º(pi/180)1= 1,4 meters. That means 0,7m to the
                                    > right,
                                    > > 0,7m to the left, 0,7m to the top and 0,7m to the bottom. If I'm not
                                    > > mistaken, this means that if you want to detect something at a
                                    > distance of 1
                                    > > meter from your robot, the transducer should be either installed at
                                    > least
                                    > > 0,7m from the floor and in 90º position, or install it in a lower
                                    > position
                                    > > but with a vertical inclination greater than 90º, so you will not
                                    > detect the
                                    > > floor (kind of reflecting floor), but you will detect things over
                                    > the robot
                                    > > (may be a problem in some cases)
                                    > >
                                    > > If I am right with this assertions, the SRF08 is good because of
                                    > the I2C
                                    > > interface, but not so good because of the beam width.
                                    > >
                                    > > I read something about putting some kind of foam around the
                                    > transducer to
                                    > > force a reduction on the detection cone. I'm not sure if it will
                                    > work, but
                                    > > I'll try it during the weekend. I'll tell you.
                                    > >
                                    > > By the way, I raised the question to Devantech Company and the
                                    > answer I got
                                    > > was: "Beam width on the SRF04/8 is a function of the transducers
                                    > and is
                                    > > fixed. For the transducers used on the SRF04/8 this is 55 degrees at
                                    > > the -6db point". Not as interesting as your answers.
                                    > >
                                    > > Best regards
                                    > >
                                    > > Alejandro Alonso Puig
                                    > > http://mundobot.com
                                    > > alejandro.alonso@m...
                                    > >
                                    > >
                                    > >
                                    > >
                                    > > -----Original Message-----
                                    > > From: dan michaels [mailto:dan@o...]
                                    > > Sent: martes, 02 de diciembre de 2003 3:48
                                    > > To: SeattleRobotics@yahoogroups.com
                                    > > Subject: [SeattleRobotics] Re: SRF08 beam angle
                                    > >
                                    > >
                                    > > --- In SeattleRobotics@yahoogroups.com, "Phil" <phil1960us@y...>
                                    > > wrote:
                                    > > > what about some sort of tuning "pipe" that you slip over the
                                    > > reciever
                                    > > > to decrease the field of view that the receiver actually sees?
                                    > > sort
                                    > > > of like blinders for a horse...
                                    > >
                                    > >
                                    > > I was thinking about the same sort of thing, but I really haven't
                                    > > much idea how to do it. Sound works differently from light. Sound
                                    > can
                                    > > go around corners, etc. Something to try might be tubes of rolled
                                    > > cardboard/plastic/etc around the transmitter with lengths at "odd"
                                    > > multiples of "quarter" wavelength. At even multiples, I think the
                                    > > sound pressure will be a minimum, but I'm not really sure about this
                                    > > stuff at all. Or possibly a megaphone/conical horn - but again it
                                    > > probably needs the correct length and end aperture size for best
                                    > > results. Good area for experimentation - plus some preliminary
                                    > > legwork into acoustics. Tell us how it goes ;-).
                                    > >
                                    > >
                                    > > - dan michaels
                                    > > www.oricomtech.com
                                    > > ============================
                                    > >
                                    > >
                                    > >
                                    > > Visit the SRS Website at http://www.seattlerobotics.org
                                    > >
                                    > > To unsubscribe from this group, send an email to:
                                    > > SeattleRobotics-unsubscribe@yahoogroups.com
                                    > >
                                    > >
                                    > > Your use of Yahoo! Groups is subject to
                                    > http://docs.yahoo.com/info/terms/
                                    >
                                    > Visit the SRS Website at http://www.seattlerobotics.org
                                    >
                                    > To unsubscribe from this group, send an email to:
                                    > SeattleRobotics-unsubscribe@yahoogroups.com
                                    >
                                    > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                                    >
                                    > Visit the SRS Website at http://www.seattlerobotics.org
                                    >
                                    > To unsubscribe from this group, send an email to:
                                    > SeattleRobotics-unsubscribe@yahoogroups.com
                                    >
                                    >
                                    > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                                  • dan michaels
                                    ... wrote: Hi Alonso, I tried to download your file ... Informe Técnico (PDF 600 kb) ... twice, but it crashed after 258KB both times,
                                    Message 17 of 17 , Dec 9, 2003
                                    • 0 Attachment
                                      --- In SeattleRobotics@yahoogroups.com, "Alejandro Alonso Puig"
                                      <alejandro.alonso@m...> wrote:

                                      Hi Alonso, I tried to download your file ... Informe Técnico (PDF 600
                                      kb) ... twice, but it crashed after 258KB both times, indicating a
                                      damaged file :-(. Anyone else have this result?

                                      - dan michaels
                                      ============================


                                      > As promised, here you have the results of my testing with the SRF08
                                      sonar
                                      > ranger during the weekend (monday was also holiday at
                                      Madrid/Spain :-)
                                      >
                                      > 1) The SRF08 follow more or less the beam pattern at
                                      > http://acroname.com/robotics/parts/R145-SRF08.html
                                      > 2) The beam could be forced to be narrower by putting some foam
                                      around. I
                                      > have reduced it 20 degrees max. If it is used excessive foam
                                      surface or try
                                      > to narrow too much the beam, the results are unpredictable.
                                      Sometimes the
                                      > transducer detect the foam and sometimes it does not detect even the
                                      > obstacles just in front. In any case, by this trick it is possible
                                      to
                                      > prevent detecting the floor when we do not want it.
                                      >
                                      > I have finished a technical document on a sonar ranger to
                                      understand how
                                      > sonar rangers "see" the surroundings. Unfortunately it is in
                                      Spanish, but
                                      > there are several figures that could help understanding. Also there
                                      are
                                      > several links in English at the bottom of the page:
                                      > http://mundobot.com/tecnica/Sonar/Sonar.htm
                                      >
                                      > Whenever I have enough time I'll translate my webpage to English
                                      >
                                      > Best regards,
                                      > Alejandro Alonso Puig
                                      > http://mundobot.com
                                      > alejandro.alonso@m...
                                      >
                                      >
                                      >
                                      >
                                      > -----Original Message-----
                                      > From: Alejandro Alonso Puig [mailto:alejandro.alonso@m...]
                                      > Sent: martes, 02 de diciembre de 2003 17:52
                                      > To: SeattleRobotics@yahoogroups.com
                                      > Subject: RE: [SeattleRobotics] Re: SRF08 beam angle
                                      >
                                      >
                                      > Yes, I thought the same as you, eliminating the width in the image
                                      in order
                                      > to narrow the figures to its real form. I saw this article. In fact
                                      I'm
                                      > working in something similar. Look at my web page site. Its in
                                      Spanish yet,
                                      > but I'll treanslate to English soon. The page is not finished, but
                                      at least
                                      > you will find a figure that represents what I'm doing with the sonar
                                      > ranger(Hardware and Software):
                                      http://mundobot.com/tecnica/Sonar/Sonar.htm
                                      >
                                      > Best regards
                                      >
                                      > Alejandro Alonso Puig
                                      > http://mundobot.com
                                      > alejandro.alonso@m...
                                      >
                                      >
                                      >
                                      >
                                      > -----Original Message-----
                                      > From: dan michaels [mailto:dan@o...]
                                      > Sent: martes, 02 de diciembre de 2003 17:24
                                      > To: SeattleRobotics@yahoogroups.com
                                      > Subject: [SeattleRobotics] Re: SRF08 beam angle
                                      >
                                      >
                                      > --- In SeattleRobotics@yahoogroups.com, "Alejandro Alonso Puig"
                                      > <alejandro.alonso@m...> wrote:
                                      >
                                      > You might also check out the following page, which shows a sweep
                                      > using such a sonar. The "image" shows extended widths of objects in
                                      > azimuth.
                                      >
                                      > http://www.hazmat.com/~mjb/projects/picsonar/
                                      >
                                      > I had often wondered about the idea of doing an inverse spatial
                                      > convolution on such an image in order to try and remove the beam
                                      > width characteristic. This might be a lot of processing for a small
                                      > microcontroller.
                                      >
                                      > - dan michaels
                                      > ======================
                                      >
                                      >
                                      > > Really interesting answers. Thanks. Dan, the graph from Acroname
                                      is
                                      > really
                                      > > clear. I'll make some tests during this weekend but it seems that
                                      > the tests
                                      > > I performed more or less agree with the graph. The measures were
                                      > taken at 1
                                      > > meter from the transducer. That is 3,28 feet and as from the
                                      > graph, the
                                      > > width at such distance is of about 80 degrees (not so far from the
                                      > 100
                                      > > degrees I measured, considering I'm not testing in an ideal
                                      > environment).
                                      > >
                                      > > In any case I think it is very wide if we really want to have some
                                      > clear
                                      > > information on the surroundings. As per trigonometry
                                      > > (Arc=angleº(pi/180)Distance), the chord (arc) detected at 1 meter
                                      > from the
                                      > > transducer is Arc=80º(pi/180)1= 1,4 meters. That means 0,7m to the
                                      > right,
                                      > > 0,7m to the left, 0,7m to the top and 0,7m to the bottom. If I'm
                                      not
                                      > > mistaken, this means that if you want to detect something at a
                                      > distance of 1
                                      > > meter from your robot, the transducer should be either installed
                                      at
                                      > least
                                      > > 0,7m from the floor and in 90º position, or install it in a lower
                                      > position
                                      > > but with a vertical inclination greater than 90º, so you will not
                                      > detect the
                                      > > floor (kind of reflecting floor), but you will detect things over
                                      > the robot
                                      > > (may be a problem in some cases)
                                      > >
                                      > > If I am right with this assertions, the SRF08 is good because of
                                      > the I2C
                                      > > interface, but not so good because of the beam width.
                                      > >
                                      > > I read something about putting some kind of foam around the
                                      > transducer to
                                      > > force a reduction on the detection cone. I'm not sure if it will
                                      > work, but
                                      > > I'll try it during the weekend. I'll tell you.
                                      > >
                                      > > By the way, I raised the question to Devantech Company and the
                                      > answer I got
                                      > > was: "Beam width on the SRF04/8 is a function of the transducers
                                      > and is
                                      > > fixed. For the transducers used on the SRF04/8 this is 55 degrees
                                      at
                                      > > the -6db point". Not as interesting as your answers.
                                      > >
                                      > > Best regards
                                      > >
                                      > > Alejandro Alonso Puig
                                      > > http://mundobot.com
                                      > > alejandro.alonso@m...
                                      > >
                                      > >
                                      > >
                                      > >
                                      > > -----Original Message-----
                                      > > From: dan michaels [mailto:dan@o...]
                                      > > Sent: martes, 02 de diciembre de 2003 3:48
                                      > > To: SeattleRobotics@yahoogroups.com
                                      > > Subject: [SeattleRobotics] Re: SRF08 beam angle
                                      > >
                                      > >
                                      > > --- In SeattleRobotics@yahoogroups.com, "Phil" <phil1960us@y...>
                                      > > wrote:
                                      > > > what about some sort of tuning "pipe" that you slip over the
                                      > > reciever
                                      > > > to decrease the field of view that the receiver actually sees?
                                      > > sort
                                      > > > of like blinders for a horse...
                                      > >
                                      > >
                                      > > I was thinking about the same sort of thing, but I really haven't
                                      > > much idea how to do it. Sound works differently from light. Sound
                                      > can
                                      > > go around corners, etc. Something to try might be tubes of rolled
                                      > > cardboard/plastic/etc around the transmitter with lengths at "odd"
                                      > > multiples of "quarter" wavelength. At even multiples, I think the
                                      > > sound pressure will be a minimum, but I'm not really sure about
                                      this
                                      > > stuff at all. Or possibly a megaphone/conical horn - but again it
                                      > > probably needs the correct length and end aperture size for best
                                      > > results. Good area for experimentation - plus some preliminary
                                      > > legwork into acoustics. Tell us how it goes ;-).
                                      > >
                                      > >
                                      > > - dan michaels
                                      > > www.oricomtech.com
                                      > > ============================
                                      > >
                                      > >
                                      > >
                                      > > Visit the SRS Website at http://www.seattlerobotics.org
                                      > >
                                      > > To unsubscribe from this group, send an email to:
                                      > > SeattleRobotics-unsubscribe@yahoogroups.com
                                      > >
                                      > >
                                      > > Your use of Yahoo! Groups is subject to
                                      > http://docs.yahoo.com/info/terms/
                                      >
                                      >
                                      > Visit the SRS Website at http://www.seattlerobotics.org
                                      >
                                      > To unsubscribe from this group, send an email to:
                                      > SeattleRobotics-unsubscribe@yahoogroups.com
                                      >
                                      >
                                      > Your use of Yahoo! Groups is subject to
                                      http://docs.yahoo.com/info/terms/
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