Loading ...
Sorry, an error occurred while loading the content.

Re: RTrak-HAB antenna thoughts

Expand Messages
  • Jason R
    As for the reason that only one station was hearing the tracker, I can t say. I can tell you that EVERY RTrak-HAB that we built is paired to a single MX145H
    Message 1 of 36 , Sep 6, 2012
    • 0 Attachment
      As for the reason that only one station was hearing the tracker, I can't say. I can tell you that EVERY RTrak-HAB that we built is paired to a single MX145H transmitter module and THEN all final alignments and tests are done using that particular module. That includes our final deviation alignment which is set a little hot, around the 4 kHz mark. We found that when down at around 3.5 kHz, the packet is a little "weak" and doesn't get reliably decoded.

      So I guess that poses the question, was the deviation re-adjusted by anyone prior to the launch? The soft slider in the config software is extremely sensitive to even the slightest movement. We align every tracker with a full blown RF service monitor that allows us to have a good measure on the transmitted tone deviation. When we made a change to the voltage divider circuit that interfaces the OpenTracker to the MX145H, we found that the audio had much more punch, but also needed to be set well down on the soft slider. The original values did not provide enough audio and even at the full max level, still only gave us 2-2.5 kHz deviation.

      Jason Rausch - KE4NYV
      RPC Electronics, LLC
      www.rpc-electronics.com


      --- In RTrak@yahoogroups.com, "Lynn W. Deffenbaugh (Mr)" <ldeffenb@...> wrote:
      >
      > On 9/6/2012 12:54 PM, James Ewen wrote:
      > >
      > > Let me guess, you're basing this opinion on data gleaned from the
      > > APRS-IS stream where only a small portion of the data is available.
      > >
      >
      > No, he's basing that opinion on the fact that he and I were in an APRS
      > QSO while the balloon was in flight and there were numerous RF-enabled
      > APRSISCE/32 instances well within the balloon's footprint but his was
      > the ONLY station report ANY receptions of the balloon.
      >
      > In every other HAB I've monitored, even pre-APRSISCE/32's unfiltered RF
      > feed, at least a FEW packets would get far enough out to hit a delaying
      > gate and show up with a line or two. In this case, every single packet
      > was gated by his mobile IGate alone.
      >
      > I'd suggest just taking the balloon's tracker out and see if any device
      > other than the mobile (what was the radio in your mobile IGate anyway)
      > receives it.
      >
      > Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32
      >
      > PS. His mobile IGate was also gating stuff for many stations around,
      > not always first.
      >
    • Keith VE7GDH
      Ben KF7VZR (got that from a June 22 message) wrote... ... Deviation is important. If it s too high (within limits) nearby stations may still be able to decode
      Message 36 of 36 , Sep 6, 2012
      • 0 Attachment
        Ben KF7VZR (got that from a June 22 message) wrote...

        > My documentation says nothing about TX audio level...
        > They've both been played with...

        Deviation is important. If it's too high (within limits) nearby stations
        may still be able to decode the tones. Distant ones where your signal
        is weaker may not be able to. You have probably heard this on a voice
        repeater or even on simplex. A distant and noisy station can be copied
        via a repeater if he backs off from the mic. If he starts shouting, the
        deviation goes up. More energy is outside the passband of the receiver
        and eventually the signal is too noisy to copy or the squelch might
        even close. If you are simplex, you can try opening your squelch. If
        you are on a repeater, you're out of luck. It's the same with packet.
        You are better off having the deviation set properly. It can be done
        by ear, but a deviation meter or service monitor would be better.
        Lacking one, just crank the deviation all of the way up and then
        start turning it down. When it starts to sound quieter, turn it down
        some more. It will get you in the ballpark, but checking the actual
        deviation would be better.

        Perhaps you could check the actual deviation before you change
        anything. So... could over-deviation explain why only one iGate
        heard you?

        73 es cul - Keith VE7GDH
        --
        "I may be lost, but I know exactly where I am!"
      Your message has been successfully submitted and would be delivered to recipients shortly.