[time-nuts] Ball/Efratom MFS-209 Rubidium GPSDO...

[Chuck Harris]

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

Chuck Harris wrote:
> Hi gang!
>
> I am in the process of repairing a Ball/Efratom MFS209 GPSDO.
>
> The MGPS unit reports that I have an ADC fault, and a feed line
> fault.
>
> I have done some testing and can easily see that the feed line has
> the proper +5V on the unit's N connector, and that it can source
> the required 200ma, but with a known good antenna, the MGPS
> controller still reports the fault.