[aprssig] Good 30m Reference?

Bob Bruninga bruninga at usna.edu
Sun Feb 4 12:14:53 CST 2007

> ...what HF path and beacon rate should I use while mobile 
> (using a 100W radio into a hamstick, won't be beaconing 
> while parked or, typically, while within VHF coverage)?
> I want to see the position get out to the internet system.

You are correct that many HF recommendations are wrong and do not help the network while helping the user.  But the answer is simple and was always the same, going back to the original APRS HF operation in 1993. (except for updating to GATE,WIDE1-1 instead of GATE,WIDE.

Beacon once every 10 minutes while mobile using the path of UNPROTO APRS VIA GATE,WIDE1-1.  This makes sure that your packet will be received by every APRS Gateway in the country (depending on propagation) and that your packet will go through the gateway to local VHF where it will go one more hop via any surrounding VHF digipeater.

Once going through all those GATES and VHF digipeaters, then there is an almost certainty that your packet will be seen by an IGate somwehre.

The WORST recommendations suggest using the path of VIA ECHO...  This is just crazy.  HF needs no digipeating, since that is what the IONOSPHERE is for.  Adding ECHO just guarantees QRM and a 50% reduction in channel capacity at the expense of EVERYONE for the ego of the few.  This is the classic "tragedy of the commons" that dooms free-public-resources.  Read about it on the fix14439.html web page.

Anyway, it is great to hear of interest in HF.  APRS has been on HF since 1992 and works very well.  The 10 minute recommendation was for boats that were underway 24 hours a day.  We found that we had good data most of the time that the sun was up.  Very poor data from midnight to sunrise.

If you are mobile on short trips, then maybe 5 minutes would be appropriate for shorter trips, but for truckers and 8 hour drivers, 10 minutes would seem the best.  HF is for long haul RF and for long haul travelers where exact precise position is not important, but general position periodically is the goal.  Since back then, everyone was running APRSdos which dead-reckons positions on display anyway, the boats or truckers progress was well estimated between infrequent reports.

So for a smoother representation of progress on a long trip, then monitor the trip with an APRS client that dead-reckons its display if the general intent is progress along a long haul route.


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