[time-nuts] difference between Oncore M12 and M12+T (useful when buying online)

John Beale beale at bealecorner.com
Sat Mar 5 22:15:49 UTC 2011


In case anyone else is shopping online for a used Motorola Oncore M12+T 
timing GPS, it's probably useful to know what I just learned:

Some online sellers offering "M12+T 100 pps GPS" may instead send you a M12 
Navigation (non-timing) GPS. The differences:

Motorola Oncore M12 Navigation GPS:
---
* Supports Motorola Binary and NMEA output
* does not have 100 Hz output
* does not have TRAIM (Timing Receiver Autonomous Integrity Monitor)
* does not have sawtooth correction output
* 1 PPS <500 ns timing

crystal nearest MMCX antenna connector is two-lead can style with bent 
leads for surface mounting
example p/n label: P183T12N12   (final "N" = "Navigation"?)

photos:
http://www.wa5rrn.com/GPS%20Other/Motorola%20M12/m12.pdf
https://picasaweb.google.com/bealevideo/GPS#5580118907079326290

Motorola Oncore M12+T Timing GPS:
---
* Supports Motorola Binary output only
* 1 Hz or 100 Hz output selectable
* TRAIM (Timing Receiver Autonomous Integrity Monitor)
* sawtooth correction ("clock granularity") message available
* 1 pps <2nS 1 Sigma, <6nS 6 Sigma (using sawtooth correction message)
* 1 pps <10nS 1 Sigma, <20nS 6 Sigma (without correction)

smaller leadless surface-mount crystals
example p/n label: P283T12T17    (final "T" = "Timing"?)

photos:
http://www.wa5rrn.com/GPS%20Other/Motorola%20M12/m12plusbrochure.pdf
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?VISuperSize&item=290308535362




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