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15850RE: [SeattleRobotics] Re: SRF08 beam angle

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  • Karim Virani
    Dec 1, 2003
      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.


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


      - dan michaels

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

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