[aprssig] YOTREPS and AIS

Robert Bruninga bruninga at usna.edu
Thu Jul 31 10:49:56 EDT 2008

>> Seems like HF APRS would be a more efficient way 
>> to send position reports than sending text files 
>> through Winlink...
> For a sailing vessel with power conservation 
> concerns there is a lot of appeal to... PACTOR 
> that acknowledges receipt...

What we have always needed in this case is something that powers
up the HF rig only to send the APRS posit, and then powers back
down.  The TX power even at 100 watts is quite insignificant to
the RX power of a typical transceiver.  RX power is about 12
Watt-Hours per hour (for a 1 amp rig) compared to 1 Watt-hour
per hour for the TX running one posit every 10 minutes.

My HF.TXT file (or is it BOATS.TXT?) has asked for someone to
build a single Xtal HF TX since about 1993.  It could be built
using only about 6 transistors and some power MOSFETS and
producce 50 Watts (for 3 seconds every 10 minutes) on the 10 MHz
frequency and fit inside a brick no larger than an HT.  The
problem has always been getting frequency stability down to 10
Hz or less.  And that *ain't* easy...  But keeping the high
quality oscillator running continuously should solve that....

But the market for HF APRS is so small.... Now that the APRS-IS
is so pervasive...

Bob, Wb4APR

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