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[aprssig] APRS Messenger now has APRS over PSK-63

Bob Bruninga bruninga at usna.edu
Mon Mar 1 04:32:41 UTC 2010


>> While you may be able to guess at the content 
>> of a garbled text message, I don't know how 
>> you would be able to guess at the missing 
>> digits of a mangled position report.  (Unless 
>> they happen to be the least significant decimal 
>> minutes values -- then the rest of the 
>> digits might still be useful.)

Actually, I think  the bigger digits are the easier to fix. He cannot move to the other side of the world in 10 minutes.  Heck, he cant even change his degrees in that amount of time unless he is near a line.  I have always wanted to try writing a routine for estimating position of garbled packets, and then using PASSALL ON to accept packets with errors on HF.  It would greatly improve decoding...

Then have the routine operate with a weighting estimator kinda based on position history.  Generally you know where he might be based on his last few course and speeds..  then make estimates of his new position over time and compare it to the error packets. Then score the highest probabiliyt of a match...

Something like that.  No, wont work for pizza delivery guy or for a postman, but if someone is running APRS HF mobile and moving, then generally he is headed somewhere...

Bob, WB4APR


>Good reasoning for Bob's suggestion of Grid Square, it's humanly 
>readable, only 6 characters so across 2 or 3 garbled receptions a person 
>can make sens of it.  It's short enough to improve reception chances.  
>The only drawback would be if you're trying to get truly detailed 
>positions from it, then Mic-E makes more sense for tracking purposes.
>
>Chris - If you're following this, it might be good to include both Mic-E 
>and Grid Square in the beacon format options when you add GPS support.  
>I'm adding it to my ToDo list for APRSISCE/32.
>
>Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32
>
>
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