And as I feared, the MGPS display is telling the truth, there
is something wrong with the GPS module's ability to check the
feed line for shorts and opens, and something wrong with the
motherboard's ADC module.

At least the communication between the MGPS and the GPS engine
is working properly...

-Chuck Harris

Chuck Harris wrote:
After chatting with John Miles, and Paul (ziggy), I was reminded
that TTL RS232 is not a good thing around a pedantic protocol
analyzer.

4V signal swings would work with the analyzer's strict +/-3V
thresholds, except for that wonderful excuse for a UART that
Trimble used, putting a big glitch dead center in each sent
bit position.

The protocol analyzer saw that glitch drop below 3V, and
just knew it was a start bit.  And, that coupled with using
9600,8,N,1 instead of Trimble's favorite 9600,8,O,1 settings
made for the interesting data smearing I was seeing.

Now, I am getting properly formed TSIP packets.

Time to decode them and see what they mean.

More later,

-Chuck Harris
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