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Re: RTrak-HAB antenna thoughts

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  • Jason R
    Ben, The TX deviation and temp compensation are two completely different things. In this case, I am referring to the TX deviation slider in the
    Message 1 of 36 , Sep 6, 2012

      The TX deviation and temp compensation are two completely different things. In this case, I am referring to the TX deviation slider in the RTrak/OpenTracker configuration software. Typically, when set here in the shop, the slider should be down towards the left end of the range and between the second and third hash marks. If you are up around the 30% mark, I can just about assure you that the deviation is off the charts and I'm surprised that anything was able to decode it.

      When the OpenTracker was first design by Scott Miller, he found resistor values for the TX audio voltage divider that was good for about 90% of the radios out there. Some of the commercial radios needed a boost and he even included a jumper on-board to short the top resistor and give that boost. When we started to design around the MX14x transmitters, we found that this audio boost was a must have, so instead of adding a jumper, we just adjusted the installed resistor value to eliminate the need of a jumper that would always need to be in place anyways. After making this change, we got the audio boost we needed, but it was pretty hot, so instead of the slider being about mid range (typical for most radios), the slider is usually on the low end.

      If you would like, I can send you a default profile that can be loaded into the config software. This will put the tracker back to factory defaults and put the audio level around the sweet spot. It may need slight tweaking, but you'll be 99% of the way there. I can send you this file after I get home. Please send me an email at jason (at) rpc-electronics.com and I will respond with the file attached. Keep in mind, any settings that you have in the tracker will be erased and you'll need to reset them.

      Jason Rausch - KE4NYV
      RPC Electronics, LLC

      --- In RTrak@yahoogroups.com, "airsix73" <ben.messinger@...> wrote:
      > My documentation says nothing about TX audio level and temp deviation being factory tuned and not to touch it. Sure wish I'd known that. I just pulled up my manual just to be sure and there is no mention of this. They've both been played with. I can tell you my audio level slider is at about 33% (no idea what it was from factory) and temp adjust is +4 (it was 0).
      > I know it isn't conclusive, but my RTrak packets have always sounded strong and clear to my ear. I'm using the UZ7HO Soundmodem as my TNC and it reliably translates them as well as all other traffic with a fair signal strength.
      > Thanks for the ongoing help everyone!
      > Ben
      > --- In RTrak@yahoogroups.com, "Jason R" <lists@> wrote:
      > >
      > > 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
        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!"
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