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
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