A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)

[texaspyro]

In your OSX output data, it is opening the serial port, reading all the files, etc.  The next thing it should show is opening the XQuartz "X11" display.  It seems like something is wrong with your X11 installation.

I forgot to mention that you need to logout/login or restart your system after installing XQuartz...

[digital_dreamer]

In your OSX output data, it is opening the serial port, reading all the files, etc.  The next thing it should show is opening the XQuartz "X11" display.  It seems like something is wrong with your X11 installation.

I forgot to mention that you need to logout/login or restart your system after installing XQuartz...

Awesome! That's all that was needed - a logout and back in.
Never thought I'd be running this in macOS. Great progress.

MAJ

BTW, this is XQuartz 2.7.11 on macOS 10.10.11 (Yosemite) on a Gigabyte GA-EX58-UD5 based hackintosh (Intel Core i7 920 (quad-core) @ 3.4GHz w/Fusion drive and NVIDIA GeForce GTX 680 GPU).

[Tom45]

I decided to watch the OCXO control voltage on my GPSDO and saw random relatively wild oscillations on my 34465 trend graph display. So I saved some log files and graphed them.

The first graph is from an 11 hour (40000 points) run. The second graph is a 20000 point run (5.5 hours). Voltage was logged once per second in all runs. The third graph shows a closeup of the spike in the second run.

This is a Symmetricom UCCM P.

Any ideas what might be going on here? Could it be that it sometimes doesn't see enough satellites?

[texaspyro]

Any ideas what might be going on here? Could it be that it sometimes doesn't see enough satellites?

You have a horrible sky view to the east...

It could be.  Lady Heather plots the number of used satellites as the CYAN colored graph at the bottom of the plot area.  See if the jumps in the green DAC plot match changes in the sat count plot. 

Thunderbolt receivers show changes in the DAC value whenever the satellites used change.  The DAC changes get smaller the better your surveyed position is.

I have noticed that some of these "UCCM" receivers seem to periodically do some kind of adjustments to their PLL settings.   I seem to remember one does something every 45 minutes or so...

[Tom45]

Actually I don't have any view to the east. The antenna is looking out a west facing window in the north west corner of my house. After getting the gpsdo I put the antenna next to the window just to verify that it worked. It seemed to be OK, at least until I decided to monitor the control voltage.

Following your suggestion I watched the number of satellites and the control voltage. Since my previous monitoring showed that it could be fine for several hours at a time, I didn't know if I would have the patience to sit it out.  But I was lucky enough to have it drop to 2 satellites for a few minutes. And sure enough, the control voltage oscillated. I moved the antenna away from the window and got a similar oscillation.

So I guess it's time to figure out how to run a longer coax outside to get the antenna in a better and permanent location.

[TheSteve]

Been running LadyHeather 5.0 for a few days now with my Trimble UCCM receiver. Check out the GPS dead zone to the north of me.

[Krytron]

[quote ...   Check out the GPS dead zone to the north of me.

Your plot missing north is normal for GPS.  Its due to the polar orbits the GPS satellites are in.

[texaspyro]

Been running LadyHeather 5.0 for a few days now with my Trimble UCCM receiver. Check out the GPS dead zone to the north of me.

Due to the satellite orbits, the size and shape of those dead zones depends upon your latitude.   In the southern hemisphere, the dead zones swap to the bottom of the map.

Here's what one looks like in New Zealand:
http://www.febo.com/pipermail/time-nuts/attachments/20161221/f152ac9c/attachment.gif

[TheSteve]

Yeah, just thought it was pretty cool how nicely LH mapped it out. You can even make out where trees are and see a slightly weaker signal in close because of the antenna tower on the east side of the antenna. I have now switched to the antenna on the opposite side of the tower and should see the weaker signal to the west.

[texaspyro]

Yeah, just thought it was pretty cool how nicely LH mapped it out. You can even make out where trees are and see a slightly weaker signal in close because of the antenna tower on the east side of the antenna. I have now switched to the antenna on the opposite side of the tower and should see the weaker signal to the west.

Try the ZU command (I think that's in V5.0) to see some other versions of the signal level maps...  from the ZU display you can click on the various maps to bring them full screen.  If ZU doesn't work try ZA, ZR, and ZE.

In V5.0 the signal level maps are based on the average signal levels seen at a given sky position since the program was started.  I've since changed that to restart the averaging (from the current average values) every 24 hours.  That way if something happens to your antenna setup,  the change in signal levels won't be swamped out by the old accumulated data.

[TheSteve]

The updates you've made are amazing. Shame my ancient HP 58501A doesn't support any commands (that I can find) to use it with LH.

[texaspyro]

The updates you've made are amazing. Shame my ancient HP 58501A doesn't support any commands (that I can find) to use it with LH.

Heather does work with the HP5xxxx/Z3816A/Z3817A devices (use the /rx5 command line option),  but with V5.0 you have to first manually configure them to turn off "full duplex" mode that echoes the serial input data.  Heather does send a command to turn off full duplex mode, but it does not work with all devices/firmwares.  The next rev sends the proper command that should work with everything.  But it sounds like your unit is so old it does not support HP's standard GPSDO command set.

[TheSteve]

I can see the commands in ASCII in the firmware I've dumped from it but none of them respond. It's a one off very early unit.

[edpalmer42]

Yeah, just thought it was pretty cool how nicely LH mapped it out. You can even make out where trees are and see a slightly weaker signal in close because of the antenna tower on the east side of the antenna. I have now switched to the antenna on the opposite side of the tower and should see the weaker signal to the west.

If possible, put the antenna on the south side of the tower.  That way, the tower isn't blocking any satellites.

Here's my antenna pattern.  I live on the top floor, south side of an apartment building.  The antenna is bolted to my balcony railing.  Nothing but sky to the east, west, and south.  Even so, this pattern took a couple of months to build up.  There were pie-shaped cutouts that were simply due to the fact that there were no satellites there.  Over time, the satellites drifted around and filled up the cutouts.

[texaspyro]

[ Even so, this pattern took a couple of months to build up.  There were pie-shaped cutouts that were simply due to the fact that there were no satellites there.  Over time, the satellites drifted around and filled up the cutouts.

That's a VERY nice antenna pattern.  You must have an exceptional sky view... mine sucks... ground level antenna,  lots of tress and obsctructions,  two story house.

The sats typically cross the sky in 6 hours and the orbits repeat every 12 hours.

Depending upon how many sats your receiver can track,  you should get a pretty much full antenna pattern within 12-24 hours.   There may be a couple of minor arcs of blackness (usually north-south) and some scallops around the edges where no sats have been.  My multi-GNSS receivers that typically track 20+ satellites fill in everything within a few hours. 

[TheSteve]

And 24 hours later this is the image with my more eastern antenna - more or less the same as expected.

[edpalmer42]

And 24 hours later this is the image with my more eastern antenna - more or less the same as expected.

You might want to check your elevation mask.  Use the S - A - E commands to see the elevation angle where the signal level drops and set the elevation mask accordingly.  In my case, a value of 15 degrees is appropriate.  AFAIK, the signals near the horizon should be excluded due to high noise levels and/or multipath which could degrade the short-term performance.  The yellow tips on your graph suggests that the mask might need to be raised a bit.

[TheSteve]

You are very correct - it is currently 5 degrees, 15 would be much more appropriate.

[K1FPV]

Hi All,
I purchased one of these GPSDO's close to a year ago. At the tie I bought it, I tried it out and it worked fine. A week or so later, I acquired a Spectracom Ageless Master Oscillator and have used that to this point to supply reference for my counter and other equipment.

This week, I decided to hook it up again and it is non-functioning. I push the RST button (I assume it is a reset button) and it merely reboots like it used to do only no 10 MHz out or 1 PPS. I hit the other reset button labeled MACI and the 2 upper green LEDs flash back and forth. In either case, I get no 10 MHZ or 1 pps.

Has anyone else encountered this? I looked back a number of pages on this thread, but saw no mention of this unless I accidentally overlooked it. It is too late to ask the seller to make good on it. I should have ran it more than a few minutes when I initially bought it.

Bill
K1FPV

[TheSteve]

Connect the main serial port to a terminal program and see what it says.

[K1FPV]

I have and it is blank! Nothing with any of the programs, "Termite" a terminal program, nothing with U-Center, and nothing with "VisualGPSview" either. It appears to have pooped the bed! There is an LED underneath the main board that is flashing however.

[enaxy]

Good point. 

[Bryan]

Sigh, my view of the sky. Facing North from a ground floor condo, with trees around.

[edpalmer42]

Sigh, my view of the sky. Facing North from a ground floor condo, with trees around.

That's why I suggested that a GPS-disciplined Rb oscillator might be the best solution for you.  There are a few Rb oscillators that have GPS disciplining built-in.  Datum/Symmetricom X72 and SA22c, Stanford Research PRS10 are three that come to mind.  But be careful.  Some firmware versions don't have that feature.  Be sure to get confirmation from the seller that his units have the feature.  Unfortunately, these units tend to be at the higher end of the price scale.

[Bryan]

Yes, just don't have the view of the sky for a GPSDO (I do have a Rubidium) , just note that the plot I uploaded was from a older Nortel unit. My Symmetricom died on me. I do have a Jupiter-T that gives a much better plot. Out of curiosity does the Elevation strength plot mean that in this case that the strength is much better at 60 degress and perhaps upping the elevation mask may reduce some multi math interference.