From the [time-nuts] mailing list

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

John Beale

Just for reference, these are the variant numbers I have for the M12+…

• Timer ———-No Battery —– P273T12T1x
• Timer ——— With Battery – P283T12T1x
• Navigation – No Battery —– P273T12N1x
• Navigation – With Battery – P283T12N1x

regards

Nigel
GM8PZR