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Re: [tracker2] AHAB

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  • Scott Miller
    ... I did run a digipeater on 144.39. I think I had QUIET set to 0, though, so it ll ignore the fact that the channel is busy. SWDCD should be ON. I was
    Message 1 of 9 , Sep 6, 2007
      > One thing that you want to be aware of is that you do NOT want to
      > digipeat on 144.390 simplex. Listen on a seperate frequency, and
      > downlink onto 144.390. Once your balloon gets a couple thousand feet
      > in the air, it will never hear a quiet time on 144.390, and will
      > appear to be locked up. Balloon borne trackers need to ignore the

      I did run a digipeater on 144.39. I think I had QUIET set to 0, though,
      so it'll ignore the fact that the channel is busy. SWDCD should be ON.
      I was using a non-standard alias, of course - don't want to digipeat
      all of southern California and Nevada's WIDEn-N traffic!

      > Scott, any chances of an OT2 in a tiny SMT version for balloon flights
      > like the OT+ SMT?

      I was thinking of an OT1+ with integrated Copernicus GPS engine and 500
      mW transmitter. (Wasn't I talking to you about that the other day,
      James?) If and when I get a compact transceiver an all-in-one T2 would
      be a possibility. In fact, I'm doing that with the more expensive
      commercial 6-watt RF boards.

      The big problem with a tiny T2 board is that the demand's not really
      high enough to warrant automated production, and the part count is
      enough to make it a pain to produce in-house.

      Scott
    • Jeremy Day
      I guess I should clear up a few things: I meant that the GPS input would be NMEA protocol. Output from the TNC to the radio is (I assume) AX.25 standard. Also,
      Message 2 of 9 , Sep 6, 2007
        I guess I should clear up a few things:

        I meant that the GPS input would be NMEA protocol. Output from
        the TNC to the radio is (I assume) AX.25 standard.

        Also, by restricted digipeat capability, I mean having the digipeater
        listen only for packets from our chase vehicles, which would (I hope)
        be the only packets on whatever frequency we chose. This frequency
        should be different from the national APRS frequency.

        Thanks to everyone for their input.

        Jeremy Day
        Communications Lead
        Auburn High Altitude Balloon Team
        space.auburn.edu
      • Scott Miller
        Ok. NMEA input is fine, of course. As I mentioned, Garmin binary mode will give you vertical speed, but you ll also get estimated position error rather than
        Message 3 of 9 , Sep 6, 2007
          Ok. NMEA input is fine, of course. As I mentioned, Garmin binary mode
          will give you vertical speed, but you'll also get estimated position
          error rather than HDOP, and time will be off a bit due to the lack of
          leap second handling in the current firmware.

          You can restrict digipeating by using a non-standard alias. I think I
          used AIR for mine. You just need to set the path appropriately on the
          stations using it.

          And to clarify further on the NMEA thing, all APRS output is going to be
          AX.25 (well, unless you're running PSK31 anyway) - but APRS lets you use
          NMEA or one of three or four other position formats within that AX.25
          packet.

          Scott

          Jeremy Day wrote:
          >
          >
          > I guess I should clear up a few things:
          >
          > I meant that the GPS input would be NMEA protocol. Output from
          > the TNC to the radio is (I assume) AX.25 standard.
          >
          > Also, by restricted digipeat capability, I mean having the digipeater
          > listen only for packets from our chase vehicles, which would (I hope)
          > be the only packets on whatever frequency we chose. This frequency
          > should be different from the national APRS frequency.
          >
          > Thanks to everyone for their input.
          >
          > Jeremy Day
          > Communications Lead
          > Auburn High Altitude Balloon Team
          > space.auburn.edu
          >
        • Bob Burns W9RXR
          ... In the words of Jeff Foxworthy, you have my attention. Tell us more. How frequency agile will these RF boards be? How much current will they draw? What s
          Message 4 of 9 , Sep 7, 2007
            At 04:25 PM 9/6/2007, Scott Miller wrote:
            >If and when I get a compact transceiver an all-in-one T2 would be a
            >possibility. In fact, I'm doing that with the more expensive
            >commercial 6-watt RF boards.

            In the words of Jeff Foxworthy, you have my attention.

            Tell us more. How frequency agile will these RF boards be? How much
            current will they draw? What's your time line for this project?

            Bob...
          • Scott Miller
            Catching up on email again... The commercial boards will do 136 to 162 MHz in 2.5 kHz steps. Transmitter attack time is under 15 ms. Current drain at 6 watts
            Message 5 of 9 , Sep 18, 2007
              Catching up on email again...

              The commercial boards will do 136 to 162 MHz in 2.5 kHz steps.
              Transmitter attack time is under 15 ms. Current drain at 6 watts is a
              little over 2 amps. Receive current is about 80 mA.

              They're really not meant for high duty cycles - the PA starts heating up
              really fast. For testing, I've bolted a couple of the largest TO-220
              heatsinks I had on hand to the thing and it does much better - I don't
              have to worry about a software glitch locking it in transmit mode for 20
              seconds and cooking the board.

              Scott

              Bob Burns W9RXR wrote:
              >
              >
              > At 04:25 PM 9/6/2007, Scott Miller wrote:
              > >If and when I get a compact transceiver an all-in-one T2 would be a
              > >possibility. In fact, I'm doing that with the more expensive
              > >commercial 6-watt RF boards.
              >
              > In the words of Jeff Foxworthy, you have my attention.
              >
              > Tell us more. How frequency agile will these RF boards be? How much
              > current will they draw? What's your time line for this project?
              >
              > Bob...
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