[time-nuts] Something better than a Thunderbolt?

Sam lists at digitalelectric.com.au
Thu May 3 14:32:44 UTC 2012


Peter,
You can display signal strength vs az/el by pressing the letters "s a s" on your keyboard.

S = Survey
A = Antenna
S = Signals


Sam.



----- Original Message -----
From: Peter Gottlieb
[mailto:nerd at verizon.net]
To: Discussion of precise time and frequency
measurement [mailto:time-nuts at febo.com]
Sent: Fri, 04 May 2012 00:00:22
+1000
Subject: Re: [time-nuts] Something better than a Thunderbolt?


> Interesting.  I wonder what other GPSDO units are out there in the cell
> systems 
> which might find their way to the surplus market?
> 
> By the way, how do you get Lady Heather to show the plot of signal strength
> vs 
> az/el?  I tried all sorts of different graphing options and read through 
> everything I could find with no luck.
> 
> Peter
> 
> 
> 
> On 5/3/2012 8:02 AM, Mark Sims 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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