[time-nuts] Am I doing something wrong?

[Roger Rehr W3SZ]

Hi All,

Sorry I forgot to attach the freq vs DAC voltage table to the email that 
I just sent:
DAC V  Freq
+5.0     9.999.961
+0.0     9.999.985
-3.0     9.999.998
-3.5     10.000.000
-3.8     10.000.001
-4.0     10.000.002
-4.5     10.000.004
-5.0     10.000.006

So the oscillator is not "centered" on 10.000.000 anymore.

73,
Roger
W3SZ

On 9/26/2019 1:06 PM, Roger Rehr W3SZ wrote:
> Hi Nigel, and Bob, and Bill!
>
> Thanks for the notes!  I very much appreciate your helpful comments.  
> I will give my responses to all of your helpful posts here.  Sorry for 
> the delay in responses.  The reason for the delay is that my 
> Thunderbolt is at a remote site and I can communicate with it via Lady 
> Heather remotely, but I had to drive out to the site to do the tests 
> with an HP 5342A frequency counter and pulse analysis of the pps 
> port.  I drove out to the site today.
>
> First, Bob and Bill,
>
> 1.
> DAC set to +0.5 V gives significant frequency errors:  HP counter 
> reads 9.999.984 MHz and osc error as reported by LH is 1,68x,xxx.xx 
> ppt.  Interestingly, at this voltage pps error is flipping between +50 
> and -50.
>
> The DAC voltage that minimizes both counter error and pps/osc error as 
> reported by LH is around -3.553 V.  This is dramatically different 
> than the setting last October when all was working well, as you know.
>
> With DAC voltage -3.553 V the osc error and pps error are reduced, but 
> they jump around quite a bit:
> pps short-term variation is for example between about +50 and -50 and 
> osc short term variation is between about +5000 and -5000.  HP counter 
> reads 10.000.000 MHz.
>
> Even when I have the DAC close enough to optimum that my counter reads 
> 10.000.000 MHz and the osc error is flipping around both sides of 
> zero, the unit stays in "Power-up" mode and the DAC voltage stays at 
> wherever I set it (either using d>>s or &>>i and then power cycle) and 
> does not vary.
>
>
> 2.
> I get a 10 usec duration +5V pulse every 1.00 seconds from the PPS 
> port, as per specifications.  I cannot give you greater precision than 
> that on the pulse interval.
>
>
> Nigel,
>
> I agree that something appears odd with this unit that had been 
> running with no problems for at least a year at my location.  There 
> have been no known system / config changes by me, although there is 
> always the chance that I fat-fingered something when playing with the 
> Lady Heather display at some point.
>
> The receiver self identifies as a TSIP (Trimble TSIP Binary) receiver 
> when Lady Heather starts up.  The receiver type is not specified in my 
> cfg file, which instead has the default line /rx which as you know 
> means auto-detect receiver type.
>
> I had assumed that the "Nortel NTGS/NTBW" designation that you mention 
> and that appears on the Lady Heather parameter display had something 
> to do with Trimble having supplied the unit I now have to Nortel and 
> this "Nortel NTGS/NTBW" designation being a custom ID placed in the 
> firmware so that the unit would be "branded" as Nortel.  This 
> supposition is consistent with line 2170 of the heather.txt file which 
> says "Trimble telecom GPSDOs (NTBW,NTPX,NTGS,etc)".  There is also a 
> line in the heather.pdf file that says, "Note that non-Thunderbolt 
> GPSDOs (such as the NTBW and NTPx telecom devices) do not all support 
> saving disciplining parameters to EEPROM and some do not allow users 
> to change the disciplining parameters. You can use "/d" command line 
> options for setting the PLL parameters from the command line. If you 
> run the auto-tune command on non-Thunderbolt devices then only the 
> satellite elevation mask (and perhaps the signal level mask) values 
> will be set".
>
> The physical unit is labeled "Trimble THUNDERBOLT", so I guess, 
> looking at all of the data, that I have a Trimble / Nortel device.
>
> But the issue of whether it is a Nortel/Trimble Thunderbolt or just a 
> Thunderbolt wouldn't cause the current problem that I am having now in 
> a unit that previously worked perfectly for me.
>
> Just so you know that my heather.cfg file is "OK" and not responsible 
> for any problems, here it is:
>
> /9
> /rx
> /br=9600:8:n:1
> /ro=1*
> /tz=-5EST/EDT
> /b=1
> /tb=W3SZ
> /gm
> /gw=0
> /gqw
> /gcs-
> /gcg
>
> To further document that this issue is not a "setup" problem, I did 
> another factory reset of the unit and then did not use Lady Heather 
> but only monitored function with TBoltMon.exe and I did not do any 
> setup with that utility until the self survey was done and more than 
> two hours had passed, and then I only set and saved the position. 
> Function and  results were unchanged, and the unit was still stuck in 
> Power-Up mode and DAC voltage was still stuck at zero, but everything 
> else was normal according to the TBoltMon readouts.
>
> Thanks again and 73,
>
> Roger
> W3SZ
>