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[aprssig] Re: Clueless Beacon on 30M HF

Stephen H. Smith wa8lmf2 at aol.com
Thu Nov 16 03:40:10 UTC 2006


ben at ben.com wrote:
> On Wed, Nov 15, 2006 at 05:58:02PM -0800, Stephen H. Smith wrote:
>   
>> 2:Fm WB7VLW To GPSLK Via RELAY,BALDI,MISION,MOXIE,WIDE3,GATE* <UI pid=F0 
>> Len=70 >[17:47:12]
>> $GPGGA,214910,4706.8793,N,12215.5971,W,1,06,2.1,185.6,M,-18.8,M,,*73
>>     
>
> Unless I misread that path, it was a 2m beacon gated onto 30m, probably
> by W7CCY.
>
>   


If that is so:

1)   What is he doing gating VHF to HF?   That's normally a no-no since 
1200 baud VHF traffic has the capability to completely monopolize the 
much slower 300 baud HF side.    And, due to propagation on 10MHz,  tie 
up the 10.149 channel over at least HALF of the US and Canada doing it.

2)  Why is he transmitting raw NMEA strings instead of compressed or 
Mic-E packets.  This string probably took over 15 seconds to send at 300 
baud.   It not only wastes the very limited channel capacity on HF, it 
absolutely minimizes the chance of being successfully received.  

ALL of a packet has to be received PERFECTLY before ANYTHING can be 
recovered from it.  This raw NMEA string that is TEN TIMES  longer than 
it needs to be simply to send a posit, absolutely maximizes the 
probability of the packet being trashed by signal fading, a pop of noise 
or other stations that can't hear him keying up on top of his transmission.



--

Stephen H. Smith    wa8lmf (at) aol.com
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