[OZAPRS] Tigertronics

[Bob Bruninga]

On Fri, 7 Nov 2003, Brian Beamish wrote:

> What I have found that whilst HF 300baud APRS works well it does though
have
> far more "Misses" than 1200buad on VHF if the HF beacons are set as I
> believe Bob suggested to 30 Minutes and you "Miss" 2 or 3 times and you
have
> travelled over 100kms maybe 200kms and a couple of hours down the road.
Miss
> a couple on 1200baud locally maybe a minute of two and you are only a
couple
> of kilometres in the city down the road.

You are correct.  Probably if I was mobile and in motion and using HF, I
would choose maybe a 5 minute rate if the channel sounded clear.  To be
honest, I havent turned the radio volume up on my HF rig in years and
dont konw how busy the 10.149.2 freq is...

Bottom line is not to load it so that it is busy all the time...It should
be quiet more than half the time...  The GOOD news is that Carrier Detect
works on HF to avoid colisions, so the channel throughput can approach 40%
without much loss due to collisions.  At 300 baud  then the channel can
support about 20 Mic-E or 7 conventional APRS packets per minute.

Divide that up by their rates and that gives the answer as to how often
each individual should transmit for his immediate mission...

Bob, WB4APR

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