[OZAPRS] Higher beacon rate HF versus VHF?

[Jack Chomley]

At 11:00 PM 3/29/2009, you wrote:
>Jacks success at being received by my HF iGate with 600mW, complaints
>about QRM etc got me thinking about beacon rates for HF vs VHF.
>
>Given the low number of HF stations, the vastness of Australia, the
>vagaries of HF and the fact that HF stations do not digipeat to HF,
>and perhaps if I go on, shouldn't digipeat to VHF, I believe beacon
>rates on HF should be higher than on VHF. What do others think?
>
>David
>VK4MDX

David,
I have been using a beacon rate of 2 minutes on my motorcycle system 
running 6 watts on 30m with an Icom 703, SCS DSP TNC, Garmin 
16-HVS  GPS.  The performance has been good over the last 12 months, 
many of the beacons were missed, but I put that down to the low power 
and antenna waving around while mobile.
Back in January, I changed the transmit format of the APRS data 
frames to the compressed format and my "hit" rate immediately went 
up. Probably because of the shorter packets, meant less chance of 
them being corrupted.
See my Jan 15th '09 track log....
http://aprs.fi/?call=VK4JRC-15&dt=1231977600&mt=m&z=11&timerange=3600
Since the hit rate has gone up, I can now lower the beacon rate and 
still get a good track record.
Bike here:
http://www.radiotelemetry.net/html/hf_mobile_aprs.html
Personally, I think that IF there are enough IGATES, there is 
probably no reason to have a high beacon rate, nor need to run 
anymore than about 20 watts, but the secret of success is to use 
compressed format APRS data.
Yesterdays test also proved that when there was QRM on the frequency, 
I managed to get some hits in between the contest stations, that were 
just off the 40m frequency. Shorter frames, less chance of corruption ;-)
My antenna for yesterday's test was a Buddipole vertical, setup on an 
8ft tripod, in the back yard, the counterpoise was 1 electric fence 
wire above ground radial, deployed towards the South. The vertical 
element a Versa-T,  1 arm section, coil, with 5 section shock-corded 
military whip, on top of the coil.
See Buddipole:
http://www.buddipole.com/

73  Jack VK4JRC





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