Symmetricom GPSDO Teardown - Page 1
Forum section: electronics / testgear

author: SteveyG
author_rank: Unknown
timestamp: February 23, 2015, 10:38:03 am
content: I've just uploaded a new video to YouTube where I take a look at a Symmetricom GPSDO. If anyone has any information on this unit, particularly the protocol for the command channel, it'd be great to hear from you.

author: The Doktor
author_rank: Regular Contributor
timestamp: February 23, 2015, 07:03:06 pm
content: I don't know anything about the unit you got, but I have heard the name a few times. I would suggest you try Lady Heather's Disciplined Oscillator Control Program, I don't know whether or not it supports your unit, but it's free and will only take you a few minutes to try it out. You can download it athttp://www.ke5fx.com/heather/readme.htmBy default it tries to open connection on COM1, if you are using a different serial port, you have to add a switch to the command line you launch the program with. For example, if you are connected on COM4, you would put /4 at the end of the command line when you want it. Make sure to include a space before the /.You could also Google "Time Nuts", I believe that will bring up some others who are interested in these types of devices, as well as other high precision timing devices.I'm sorry I can't be more helpful, I hope this works out for you. But even without further information, I think you already got things solved. I would say almost positively that when the green light is on solid, you are fully locked into the satellites, and ready to go. All you need to do now is get yourself a 10 MHz output.Ed

author: SteveyG
author_rank: Unknown
timestamp: February 23, 2015, 08:53:12 pm
content: Hey Ed, thanks for the reply. Actually I came across the Lady Heather program and tried it out but I get absolutely zero traffic back from the unit. To be honest, so long as it locks I'm happy, although it would be nice to see all the info available from the unit.

author: Vgkid
author_rank: Super Contributor
timestamp: February 23, 2015, 09:02:50 pm
content: Congrats, on getting a gpsdo. I feared that it used a 2.048MHZ oscillator, which is a divide by 4 of 8.192MHZ. How far off is your counter.

author: aroby
author_rank: Regular Contributor
timestamp: February 23, 2015, 09:42:37 pm
content: Quote from: SteveyG on February 23, 2015, 08:53:12 pmThe unit probably just takes SCPI commands so you could try the Satstat software athttp://www.realhamradio.com/gps-satstat-software.htm. If that doesn't work, you can try raw SCPI commands, although you ought to see a scpi> prompt. There are other units that continually send out the time, and you need to put them into scpi mode:> To go to the SCPI mode:> ptim:tcod:cont 0>> To go to the continuous time mode:> ptim:tcod:cont 1You could try *IDN? and :SYSTEM:STATUS? and see what they come back with.

author: bingo600
author_rank: Super Contributor
timestamp: February 23, 2015, 09:44:32 pm
content: LH is written for Trimble units/TSIP protocol/Bingo

author: SteveyG
author_rank: Unknown
timestamp: February 24, 2015, 03:03:51 pm
content: Thanks for the info. I may have found a PDF of an almost identical unit marketed under a different brand (Alvarion), which seems to imply that it should support TSIP:"The GPS Receiver may be configured, and will report both status andsatellite conditions via the CDU port, utilizing an upgraded TSIPprotocol."But it gives no more details than that. I'll tinker more later...