[time-nuts] Something better than a Thunderbolt?
garnere at gmail.com
Mon May 7 17:05:48 UTC 2012
My apologies if is missed it, but will there be "official" support of
the nortel version in some future release of LH?
On Thu, May 3, 2012 at 5:02 AM, Mark Sims <holrum at hotmail.com> wrote:
> Recently Sam managed to poke and prod a Trimble/Nortel GPSTM (NTGS50AA) enough to wake it up out of its slumber and be recognized by Lady Heather. The NTGS50AA is a version of the Thunderbolt done for Nortel. It has some interesting features (like hot-upgradable firmware, single 24 or 48V power input, cheaper than a tbolt, etc. It also has a few warts... no TSIP command documentation being the main one and a few commands are definitely different than the Tbolt.
> The wakeup technique is rather crude and can take a couple of minutes (shout a particular command into its ear until it wakes up). Trimble's software manages to get it talking immediately. Duplicating the commands that Trimble sends does not seem to work. Once it wakes up, it stays awake until you power cycle it or run Trimble's software.
> I purchased one of these units from an Ebay seller in Old Cathay (around $70 or make offer plus $30 shipping) to see what it would take to add support to Lady Heather. My unit came in a week or so later. I hacked a 48V power connection (literally) onto the board and powered it up with a wall wart. After some futzing and puzzling over the proper ribbon cable orientation between the main board and front panel board, I got the unit woken up using Sam's technique and puzzled out the commands to make the oscillator disciplining (time constant, damping, dac gain, etc) work. The old survey location was in a sketchy Guatemalan smuggler's haven border town at what looks like a private residence.
> After running it a while, it became apparent that it works better than the Thunderbolt. The temperature sensor does not have those glitches that plague the tbolt. The receiver has a bit more sensitivity. And, best of all, the oscillator is pretty much immune to external temperature changes (the Tbolt oscillator makes a good thermometer). The reported OSC and PPS rms errors are exceedingly low... you have to actively thermally stabilize the Tbolt to approach these numbers. Hopefully this quality extends to its phase noise, etc spec. It would be interesting to see what thermally stabilizing the unit would do...
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