[amsat-bb] GO-32 Mobile Receive Success
bruninga at usna.edu
Thu Oct 11 04:55:07 PDT 2007
> Tonight I finally remembered to set my D700 in
> my van to the 435.225 GO32 downlink.... I was
> not disappointed. Received over 150 packets
> during the central 6 minutes of the pass.
I have now plotted that data on the APRS GO-32 page:
It clearly shows that the mobile link works at elevations above
about 25 degrees and a quick look at GO32 passes reveals that
they occur every day within an hour or so of 10 AM and 9 PM
local DST time. (Your times may vary +/- 30 minutes from that
depending on where you live relative to the center of your time
> I was just making hash marks
> on the back of an envelope while watching the packets fly by
> on the front panel of the radio. I did tune 3 times for
> Doppler since I was just sitting there with nothing else to
> This confirms that an unattended D700 or D7 hooked to a
> simple OMNI antnena (and short coax) can make an excellent
> APRS satellite gateway. With say a dozen of these across the
> USA, then the APRS-Internet system should get a solid
> After the fact, I came in and looked at the pass on
> Instantrack. Here is the nitty-gritty showing the elevation
> angle versus number of packets received per minute.
> TIME EL PACKETS
> 0933 30 18
> 0934 40 23
> 0935 46 36
> 0936 45 35
> 0937 36 24
> 0938 26 13
> For an unattended ground station without Doppler tuning, my
> guess would be that this station would have received the
> center full 3 minutes of this 45 degree pass.
> So, what is your handy D7 doing sitting on your shelf turned
> off? Hook it to a 19" vertical whip over a ground plane
> outside your window and contribute to the National GO-32
> APRS downlink system!
> Ill get someone to write a simple turn-key APRS IGate
> background application, so you don't have to hasssle with all
> the other APRS stuff if you dont want to. This way, you can
> just turn on the D7, hook it to a serial port, run this
> application in the background, and you too will be a
> contributor to the solid APRS downlink from GO-32!
> Oh, On the D700, I had pressed the PACKET MONITOR button so
> that I was seeing all GO-32 downlink packets on the front
> panel, not just the APRS ones. The D7 does not have the PMON
> button, so you will only see the APRS packets. But I did
> receive the 3 APRS downlink bulletins perfectly many times,
> and every 30 seconds or so, I did receive the GO-32 TIME
> STATUS report on the front panel of the radio.
> So, even if you are not going to Igate, just hook that D7 to
> an outside 19" vertical whip (this serves as a 3/4 wave gain
> vertical on the 435 downlink) through a short coax (Antnena
> height does not matter, coax loss does!). You won't hear
> anything below 30 degrees anyway... And just leave the HT on
> all the time tuned to 435.230. Every morning and every
> evening, you will receive GO-32 and any other APRS operators
> playing that evening.
> When you hear good signals on 435.230, then 2 minutes later,
> switch to 435.225 and so on. When the pass is over, set your
> radio back to 435.230 for the next HIGH pass 12 hours or so
> You can leaave this on all the time, since it will not wake
> you up. GO-32 PEAK passes are within an hour or so of 9 AM
> and PM local time (maybe an hour later after the change back
> to standard time)..
> Thousands of AMSAT folks have these D7's, and I bet that 99%
> of them are not in use most of the time. All we need are a
> dozen or so serving this space-diversity ground station
> Bob, Wb4APR
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of
> the author.
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