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Setting audio input level?

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  • captcurt@flash.net
    GA All: I have seen many posts and questions on the issues that show up when the audio input level is too high but have missed a technical process for actually
    Message 1 of 7 , Sep 8, 2010
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      GA All:

      I have seen many posts and questions on the issues that show up when the audio input level is too high but have missed a technical process for actually setting it.

      Without having a deviation meter, how does one actually set the proper audio input level when using an APRS device?

      How I've done it in the past:

      1. Listened to the signal using a second rx and adjusting the audio level until it "sounds like it isn't overdriving" Going a little further, using a second rx, actually use a PC and APRS decoder to monitor the signals. This is pretty cumbersome and requires a second rx and decoder and a dummy load.

      -OR-

      2. Using a 10x or fet scope probe, monitor the microphone input signal level when speaking in a normal "communications" level voice. Set the APRS audio input to the same level. This of course only works if you are using the mic input. It might work if the packet or data input is in the same chain and you track down a common point to monitor the audio. Again, pretty time consuming.

      Is there an accurate way that yields an effective deviation result or is the decoding process so robust that any deviation under the max within reason works OK?

      Thanks,

      Curt
    • captcurt@flash.net
      So...it looks like no one knows or no one wants to share?
      Message 2 of 7 , Sep 17, 2010
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        So...it looks like no one knows or no one wants to share?


        --- In tracker2@yahoogroups.com, "captcurt@..." <captcurt@...> wrote:
        >
        > GA All:
        >
        > I have seen many posts and questions on the issues that show up when the audio input level is too high but have missed a technical process for actually setting it.
        >
        > Without having a deviation meter, how does one actually set the proper audio input level when using an APRS device?
        >
        > How I've done it in the past:
        >
        > 1. Listened to the signal using a second rx and adjusting the audio level until it "sounds like it isn't overdriving" Going a little further, using a second rx, actually use a PC and APRS decoder to monitor the signals. This is pretty cumbersome and requires a second rx and decoder and a dummy load.
        >
        > -OR-
        >
        > 2. Using a 10x or fet scope probe, monitor the microphone input signal level when speaking in a normal "communications" level voice. Set the APRS audio input to the same level. This of course only works if you are using the mic input. It might work if the packet or data input is in the same chain and you track down a common point to monitor the audio. Again, pretty time consuming.
        >
        > Is there an accurate way that yields an effective deviation result or is the decoding process so robust that any deviation under the max within reason works OK?
        >
        > Thanks,
        >
        > Curt
        >
      • Fred Hillhouse
        Actually it is in the archives and Google-able but at the moment I would have to search the archives or Google it as well. Fred _____ From:
        Message 3 of 7 , Sep 17, 2010
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          Actually it is in the archives and Google-able but at the moment I would have to search the archives or Google it as well.
           
          Fred
           


          From: tracker2@yahoogroups.com [mailto:tracker2@yahoogroups.com] On Behalf Of captcurt@...
          Sent: Friday, September 17, 2010 09:40
          To: tracker2@yahoogroups.com
          Subject: [tracker2] Re: Setting audio input level?

           

          So...it looks like no one knows or no one wants to share?

          --- In tracker2@yahoogroups.com, "captcurt@..." <captcurt@...> wrote:
          >
          > GA All:
          >
          > I have seen many posts and questions on the issues that show up when the audio input level is too high but have missed a technical process for actually setting it.
          >
          > Without having a deviation meter, how does one actually set the proper audio input level when using an APRS device?
          >
          > How I've done it in the past:
          >
          > 1. Listened to the signal using a second rx and adjusting the audio level until it "sounds like it isn't overdriving" Going a little further, using a second rx, actually use a PC and APRS decoder to monitor the signals. This is pretty cumbersome and requires a second rx and decoder and a dummy load.
          >
          > -OR-
          >
          > 2. Using a 10x or fet scope probe, monitor the microphone input signal level when speaking in a normal "communications" level voice. Set the APRS audio input to the same level. This of course only works if you are using the mic input. It might work if the packet or data input is in the same chain and you track down a common point to monitor the audio. Again, pretty time consuming.
          >
          > Is there an accurate way that yields an effective deviation result or is the decoding process so robust that any deviation under the max within reason works OK?
          >
          > Thanks,
          >
          > Curt
          >

        • James Ewen
          Don t get your panties in a bunch, just read on... ... ... ... ... Well, if I came up with another process, would you then say, That s
          Message 4 of 7 , Sep 17, 2010
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            Don't get your panties in a bunch, just read on...

            On Wed, Sep 8, 2010 at 5:19 PM, captcurt@... <captcurt@...> wrote:

            > Without having a deviation meter,

            <snip>

            Don't want to do any of this:

            > 1. Listened to the signal using a second rx and adjusting the audio
            > level until it "sounds like it isn't overdriving"  Going a little further,
            > using a second rx, actually use a PC and APRS decoder to monitor
            > the signals.  This is pretty cumbersome and requires a second rx and
            > decoder and a dummy load.

            <snip>

            Don't want to do this either:

            > 2. Using a 10x or fet scope probe, monitor the microphone input signal
            > level when speaking in a normal "communications" level voice.  Set the
            > APRS audio input to the same level.  This of course only works if you
            > are using the mic input.  It might work if the packet or data input is in
            > the same chain and you track down a common point to monitor the audio.
            > Again, pretty time consuming.

            <snip>

            So then after listing ways to check deviation, and discounting them, you ask:

            > Is there an accurate way that yields an effective deviation result

            Well, if I came up with another process, would you then say, "That's
            too cumbersome as well!"?

            > or is the decoding process so robust that any deviation under the max
            > within reason works OK?

            We kind of go over this topic again, and again, and again.

            The simplest solution, using readily available equipment that just
            about ANY ham will have, is to simply listen to the audio, starting at
            the top, turn it down until you hear a change in the audio, then turn
            it down some more. There's lots of room for variance, as long as the
            audio is not clipping.

            Most amateur radio operators will probably have a radio, or at least
            know someone that will have a radio. That's not a lot to ask of a
            person. If having to figure out how to turn the radio on, tune it to
            144.390, and then listen is far too complex of a task, then you're in
            the wrong hobby. 8)

            If I handed you a bucket of ice cream and a spoon, and asked you what
            flavour the ice cream was, what would you do? Nope, don't want to go
            to the trouble of lifting the spoon, scooping some out and tasting
            it... too cumbersome. Don't look at the label and read the name, no
            sniffing, no looking at it to see if you might be able to tell just
            from the colour. How are you going to determine the flavour?

            Does that help a bit? See where you've got us?

            Using a second receiver and listening to the audio will get you in the
            ballpark. If you're in the ballpark, the other stations will decode
            you and you're set. If you're somewhere in outfield and banging up
            against the wall, dropping packets here and there, adjust a little
            more to midfield.

            Another option that you have is to take your gear to the local radio
            shop, and ask them to set the deviation on it for you using their
            communications monitor. You're going to have to instruct them on how
            to hook the unit up, how to get it into calibration mode, and where to
            tweak the calibration. After that, and you've parted with $100 you'll
            be pretty much right where you could have been by yourself with a
            simple HT tuned to 144.390 and a little work with your ear.

            There's a lot of room for quality decode modulation levels in there.
            It's not like with a communications monitor you'll be able to tweak it
            to the absolute perfect setting that will get you decoded 10 times
            further away than anyone else. If the audio is in there and not
            clipping, it will work. The problems that will bite you next are from
            multipath, flutter, picket fencing, signal fade, or just plain being
            clobbered by other packets, and that's all just part of playing with
            RF over the airwaves.

            James
            VE6SRV
          • captnkliegle
            As James said.... it ain t a home brew DSTAR repeater, VERY sensitive to audio levels for proper decoding. Been using the TSAR* method for ~20 years on APRS
            Message 5 of 7 , Sep 20, 2010
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              As James said.... it ain't a home brew DSTAR repeater, VERY sensitive to audio levels for proper decoding.

              Been using the TSAR* method for ~20 years on APRS and 'normal' AX.25 packet comms.


              * That Sounds About Right

              73 de Kriss KA1GJU (3-9) lol



              --- In tracker2@yahoogroups.com, James Ewen <ve6srv@...> wrote:
              >
              > Don't get your panties in a bunch, just read on...
              >
              > On Wed, Sep 8, 2010 at 5:19 PM, captcurt@... <captcurt@...> wrote:
              >
              > > Without having a deviation meter,
              >
              > <snip>
              >
              > Don't want to do any of this:
              >
              > > 1. Listened to the signal using a second rx and adjusting the audio
              > > level until it "sounds like it isn't overdriving"  Going a little further,
              > > using a second rx, actually use a PC and APRS decoder to monitor
              > > the signals.  This is pretty cumbersome and requires a second rx and
              > > decoder and a dummy load.
              >
              > <snip>
              >
              > Don't want to do this either:
              >
              > > 2. Using a 10x or fet scope probe, monitor the microphone input signal
              > > level when speaking in a normal "communications" level voice.  Set the
              > > APRS audio input to the same level.  This of course only works if you
              > > are using the mic input.  It might work if the packet or data input is in
              > > the same chain and you track down a common point to monitor the audio.
              > > Again, pretty time consuming.
              >
              > <snip>
              >
              > So then after listing ways to check deviation, and discounting them, you ask:
              >
              > > Is there an accurate way that yields an effective deviation result
              >
              > Well, if I came up with another process, would you then say, "That's
              > too cumbersome as well!"?
              >
              > > or is the decoding process so robust that any deviation under the max
              > > within reason works OK?
              >
              > We kind of go over this topic again, and again, and again.
              >
              > The simplest solution, using readily available equipment that just
              > about ANY ham will have, is to simply listen to the audio, starting at
              > the top, turn it down until you hear a change in the audio, then turn
              > it down some more. There's lots of room for variance, as long as the
              > audio is not clipping.
              >
              > Most amateur radio operators will probably have a radio, or at least
              > know someone that will have a radio. That's not a lot to ask of a
              > person. If having to figure out how to turn the radio on, tune it to
              > 144.390, and then listen is far too complex of a task, then you're in
              > the wrong hobby. 8)
              >
              > If I handed you a bucket of ice cream and a spoon, and asked you what
              > flavour the ice cream was, what would you do? Nope, don't want to go
              > to the trouble of lifting the spoon, scooping some out and tasting
              > it... too cumbersome. Don't look at the label and read the name, no
              > sniffing, no looking at it to see if you might be able to tell just
              > from the colour. How are you going to determine the flavour?
              >
              > Does that help a bit? See where you've got us?
              >
              > Using a second receiver and listening to the audio will get you in the
              > ballpark. If you're in the ballpark, the other stations will decode
              > you and you're set. If you're somewhere in outfield and banging up
              > against the wall, dropping packets here and there, adjust a little
              > more to midfield.
              >
              > Another option that you have is to take your gear to the local radio
              > shop, and ask them to set the deviation on it for you using their
              > communications monitor. You're going to have to instruct them on how
              > to hook the unit up, how to get it into calibration mode, and where to
              > tweak the calibration. After that, and you've parted with $100 you'll
              > be pretty much right where you could have been by yourself with a
              > simple HT tuned to 144.390 and a little work with your ear.
              >
              > There's a lot of room for quality decode modulation levels in there.
              > It's not like with a communications monitor you'll be able to tweak it
              > to the absolute perfect setting that will get you decoded 10 times
              > further away than anyone else. If the audio is in there and not
              > clipping, it will work. The problems that will bite you next are from
              > multipath, flutter, picket fencing, signal fade, or just plain being
              > clobbered by other packets, and that's all just part of playing with
              > RF over the airwaves.
              >
              > James
              > VE6SRV
              >
            • djhuff@rockwellcollins.com
              On the theme of beating this dead horse, I will send the link everyone else sends. N8UR on Layer One (physical layer tuning)
              Message 6 of 7 , Sep 21, 2010
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                On the theme of beating this dead horse, I will send the link everyone else sends.
                N8UR on Layer One (physical layer tuning)

                http://www.febo.com/packet/layer-one/index.html

                Dave W0IM





                From:        "captnkliegle" <kliegle@...>
                To:        tracker2@yahoogroups.com
                Date:        09/20/2010 05:24 PM
                Subject:        [tracker2] Re: Setting audio input level?
                Sent by:        tracker2@yahoogroups.com




                  > <snip>

                As James said.... it ain't a home brew DSTAR repeater, VERY sensitive to audio levels for proper decoding.

                Been using the TSAR* method for ~20 years on APRS and 'normal' AX.25 packet comms.

                * That Sounds About Right

                73 de Kriss KA1GJU (3-9) lol

                > <snip>
                >



              • captcurt@flash.net
                Thank You Dave...this is exactly the kind of information I was looking for. Not the rude comments about finding another (not so technical) hobby ;) 15,000
                Message 7 of 7 , Oct 9, 2010
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                  Thank You Dave...this is exactly the kind of information I was looking for.

                  Not the rude comments about finding another (not so technical) hobby ;)

                  15,000 miles of nearly 100% tracking should have indicated that I actually knew how to get it in the ball park.

                  Curt
                  KU8L

                  --- In tracker2@yahoogroups.com, djhuff@... wrote:
                  >
                  > On the theme of beating this dead horse, I will send the link everyone
                  > else sends.
                  > N8UR on Layer One (physical layer tuning)
                  >
                  > http://www.febo.com/packet/layer-one/index.html
                  >
                  > Dave W0IM
                  >
                  >
                  >
                  >
                  >
                  > From: "captnkliegle" <kliegle@...>
                  > To: tracker2@yahoogroups.com
                  > Date: 09/20/2010 05:24 PM
                  > Subject: [tracker2] Re: Setting audio input level?
                  > Sent by: tracker2@yahoogroups.com
                  >
                  >
                  >
                  > > <snip>
                  > As James said.... it ain't a home brew DSTAR repeater, VERY sensitive to
                  > audio levels for proper decoding.
                  >
                  > Been using the TSAR* method for ~20 years on APRS and 'normal' AX.25
                  > packet comms.
                  >
                  > * That Sounds About Right
                  >
                  > 73 de Kriss KA1GJU (3-9) lol
                  >
                  > > <snip>
                  > >
                  >
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