[time-nuts] pp2s? No, 1pps from a Nortel GPSTM!

[Tom Van Baak]

Hi Nate,

Nice page. Thanks for sharing your work.

The Nortel units are a reasonable and slightly cheaper alternative to a TBolt, if you don't mind the much larger size, mass, and non-standard connector issues.
The performance depends somewhat on which vendor's oscillator was used. I tested a bunch here:
http://www.leapsecond.com/pages/nortel/
For NTP none of these plots matter (most GPSDO are a thousand to a million times more stable than NTP or a PC can handle).

/tvb

----- Original Message ----- 
From: "Nathaniel Bezanson" <myself at telcodata.us>
To: <time-nuts at febo.com>
Sent: Monday, May 25, 2015 7:08 PM
Subject: [time-nuts] pp2s? No, 1pps from a Nortel GPSTM!


> As anyone with a Nortel GPSTM knows, it's a close cousin to the Thunderbolt but not exactly identical. Notably, coming from a CDMA environment, the unit has an "even second" output, aka PP2S, aka 0.5pps, aka 0.5Hz, etc. (Hoping to make this searchable...) There are software commands to configure this on the Thunderbolt too, but the GPSTM appears to have this function hard-coded into the PAL, and it can't be set back to PPS in software.
> However, there exists a PPS signal on the PCB, at TP13 between the Trimble chip and the PAL, discovered by some folks at the hackerspace here, during some noodling-around with an oscilloscope this afternoon. It's all documented here:
> https://www.i3detroit.org/wiki/Nortel_GPSTM
> This is for a NTBW50AA-11 module (single long board), other parts may have the signal in different places but I bet it's in there. 
> Enjoy!-Nate B-