[time-nuts] Suggestion for a timing GPS receiver (Trimble / Ublox / other?)

Paride Legovini pl at ninthfloor.org
Mon Jan 22 10:38:01 EST 2018

Dear fellow nuts,

I plan to build a decent GPS/GNSS-based Stratum 1 NTP server, and I'm
looking for a good and possibly affordable timing GPS receiver.

As far as I can tell there are a few common options. One is the Trimble
Resolution T (or SMT), that should be good and proven. The major
annoyance is converting the 3.3V TTL serial logic-level to RS232, but
should be doable with a MAX3232 and a few capacitors.

Another option is this UBLOX LEA-5T:


The seller advertises an RS232 output pin, but I'm not sure it's
actually available, and I'd need at least lines, one for the NMEA
strings and one for the 1PPS signal. So, even if a RS232 TX pin is
actually there, it is probably not enough to build a good reference
clock, and I'd still need to convert some TTL levels to RS232...

Does anybody have experience with this receiver?
How does it compare to the Resolution T/SMT?

Another option is the Trimble Thunderbolt. This seems to do exactly what
I need, but it costs at least ten times more than the other modules.
Beside coming with a ready to use RS232 port and a nice case, does it
have other advantages?

Am I overlooking something or missing interesting options?


Paride IZ3SUS

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