==== Differences between Oncore M12 and M12+T (useful when buying online) ====


//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