[aprssig] APRS -- Chicago to Mackinac Island sailboat race

Robert Bruninga bruninga at usna.edu
Tue Mar 27 11:54:08 EDT 2007

> You are welcome to transmit a moving position report more
> when underway, so that a lost packet does not have as much of
> impact.  At the Naval Academy, we used 10 minutes per boat,
> we had our own frequency. 

Oh, and TX power from  the battery is completely insignificant
even at the 10 minute rate.  The SEA2222 SSB transcievers we
were using drew about 1 amp just on receive.  The TX power was
insignificant in comparison even though it was 20 amps for 2
seconds every 10 minutes.  That is only 33 mA AVERAGE TX power
compared to 1000 mA continuous for the receiver.  So TX power
was only 3% of the radio system power.

Bottom line, APRS TX power is usually completely insignificant
to RX power.

Unfortunately, when I convinced the skippers how insignificant
the TX power was, it also convinced them how significant the RX
power was, so they often ended up turning off the Transceiver
completely, so they could justify keeping their boom-boxes
blaring all day instead...  They said they would turn it on
now-and-then..  But having a human in the loop almost guarantees

Oh well.  Human nature must be included in all designs.  Plan on
it... But don't save power on TX.  It is insignificant... And
MAX TX power is always better!


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