A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver) - Page 1
Forum section: electronics / projects

author: uski
author_rank: Frequent Contributor
timestamp: November 24, 2015, 09:44:48 pm
content: Hi there !I wanted to share the latest addition to my lab, a GPSDOFirst I acquired a surplus used Symmetricom GPSDO PCB off eBay.Had to buy the corresponding pigtails separately.The board had a oily and smelly (organic solvent ?) liquid on it so I had to wash it with IPA and let it dry... the wonders of Chinese surplus parts...Then I made a little case using a Hammond box :I mounted the PCB with adhesive stand-offs :The PCB sits at the top of the box because I put the adhesive feets on the removable panel - not sure if it's wise as I don't know if the adhesive will be strong enough. If I have issues I'll revert the labels and everything.There is a 1 PPS and a 10 MHz output, GPS antenna input, and a 5V 3A power supply input, all on the back :I moved the status LEDs which were on the PCB to the front panel ; there are two switches that I didn't move as their purpose is not fully understood and they don't seem to be needed for operation.(I think I know what the RST switch does... but if anyone knows what the MACT switch does, let me know !)These units seem very similar to various other GPSDOs I've seen used in the time-nuts community.The GPS receiver is aFuruno GT-8031 moduleand a +5VDC bias is provided at the antenna port.It is a 16-channel GPS timing module that supports T-RAIM and SBAS, not the latest generation but not as old as the modules used in many other GPSDOs.This particular GPSDO unit has been first powered on in 2009 or 2011 (can't remember - logs have since been cleared) so it's pretty recent.There is a console port (RS232 levels, and it's possible to tap into 3.3V signals before the level shifter chip, some cousin of MAX3232) which I connected to a DB9 port for diagnosis, I didn't make a hole for it yet since I'm not sure I'll keep it a DB9 or I'll put an integrated RS232-to-USB converter or even a small LCD with an arduino or similar, showing basic status information. But the LEDs are mostly enough.So while I decide what to do with the console, I made a little adapter that I can use for initial setup and testing :The features are decent, for instance the unit will generate an alarm (and light up the corresponding LED) if the GPS antenna is disconnected so I guess it does a bit of self-monitoring.If it goes into holdover for too long (for instance, something is jamming the GPS signals but the antenna is still there), then it will generate an alarm too. I think the time it waits before setting an alarm can be changed.Settings are 57600 8N1 no flow control and the commands look like SCPI.Sending a question mark ? then pressing ENTER gives a list of the supported commands :Code:UCCM-P > ?*IDN?ALARm:HARDware?ALARm:OPERation?DIAGnostic:OUTPut ON|OFFOUTPut:ACTive:ENABleOUTPut:ACTive:DISableOUTPut:ACTive:HOLDover:DURation:THReshold <seconds>OUTPut:ACTive:HOLDover:DURation:THReshold?OUTPut:INACTiveOUTPut:INACTive?OUTPut:STATe?SYNChronization:HOLDover:DURation:STATus:THReshold <seconds>SYSTem:PRESetSYNChronization:TFOMerit?LED:GPSLock?SYNChronization:FFOMerit?GPS:POSition N or S,<deg>,<min>,<sec>,E or W,<deg>,<min>,<sec>,<height>GPS:POSition?GPS:POSition:HOLD:LAST?GPS:REFerence:ADELay <numeric value>GPS:REFerence:ADELay?GPS:SATellite:TRACking:COUNt?GPS:SATellite:TRACking?DIAGnostic:ROSCillator:EFControl:RELative?SYNChronization:TINTerval?DIAGnostic:LOG:READ:ALL?DIAGnostic:LOG:CLEarSYSTem:PONOUTPut:MODE?SYSTem:STATus?SYSTem:COMMunication:SERial1:BAUD 9600|19200|38400|57600SYSTem:COMMunication:SERial1:BAUD?SYSTem:COMMunication:SERial1:PRESetSYSTem:COMMunication:SERial2:BAUD 9600|19200|38400|57600SYSTem:COMMunication:SERial2:BAUD?SYSTem:COMMunication:SERial2:PRESetOUTPut:STANby:THReshold <seconds>changeSNSYNChronization:REFerence:ENABLE LINK|GPSSYNChronization:REFerence:DISABLE LINK|GPSSYNChronization:REFerence:ENABLE?STATusPOSSTATusTOD EN|DITIME:STRing?REFerence:TYPE GPS|LINKREFerence:TYPE?PULLINRANGE 0|1|2|...|254|255PULLINRNAGE?DIAGnostic:LOOP?DIAGnostic:ROSCillator:EFControl:DATA GPS|<value>DIAGnostic:ROSCillator:EFControl:DATA?OUTPut:TP:SELection PP1S|PP2SOUTPut:TP:SELection?GPSystem:SATellite:TRACking:EMANgle <degrees>GPSystem:SATellite:TRACking:EMANgle?DIAGnostic:TCODe:STATus:AMASkDIAGnostic:TCODe:STATus:OMASkDIAGnostic:TCODe:ERRor:AMASkDIAGnostic:TCODe:ERRor:OMASkDIAGnostic:HOLDover:DELayDIAGnostic:HOLDover:DELay?GPS:SATellite:TRACking:IGNore <PRN>, ...,<PRN>GPS:SATellite:TRACking:IGNore?GPS:SATellite:TRACking:INCLude <PRN>, ...,<PRN>GPS:SATellite:TRACking:INCLude?GPS:SATellite:TRACking:<select>:ALLCommand CompleteUCCM-P >The prompt isUCCM-P>The identification is (I blanked the last 4 digits of the serial) :Code:UCCM-P > *IDN?Symmetricom,090-03861-03,W56094xxxx,1.0.0.2-01Command CompleteI believe these were used in GSM/UMTS/CDMA base stations. There was a log in my unit, latest GPS fix was located at the top of a high building in Japan.At bootup it goes through several states :OCXO WARMUPOCXO WARMACTIVEThe ACT LED corresponds to the PLL lock :Green solid : PLL unlockedGreen flashing slowly : PLL locking ("adjusting freq" then "syncing")Green flashing fast : PLL locked to GPSWhile the PLL locks I can see the frequency change slightly on the output.In parallel, at power on, the receiver starts doing an initial GPS survey by averaging the GPS positions, takes 2 hours to finish and needs good GPS signal quality.If GPS signal quality gets too low (low elevation or not enough sats in view), the survey will be paused and will resume later.Boot prompt is :Code:Symmetricom Boot Code ver. 1.01.01Press Enter to go to bootImage1: [1.0.0.2] [454535 bytes] [valid checksum:0x20AFA24] [timestamp:3]Image2: [1.0.0.1] [454535 bytes] [valid checksum:0x2142B89] [timestamp:2]Loading Image1UCCM-P >There are a few status commands :Code:UCCM-P > SYST:STAT?-------------------------------------------------------------------------------090-03861-03 serial number W56094xxxx firmware ver 1.0.0.2-01 LINK mode-------------------------------------------------------------------------------Reference Status __________________________ Reference Outputs _______________Ref 8KHz 0: TFOM 2 FFOM 0UCCM-P Status>> GPS: [phase: 2.77e-08]ACQUISITION ................................................ [ GPS 1PPS Valid ]Tracking: 10 ____ Not Tracking: 1 ________ Time ____________________________PRN El Az C/N PRN El Az GPS 19:08:57 24 NOV 20155 22 87 36 10 Not OK GPS Synchronized to UTC13 53 56 37 ANT DLY +0.000E+0015 83 160 42 Position ________________________18 36 282 38 MODE Hold20 73 60 4021 56 295 39 LAT N 45:29:xx.xxx24 16 162 34 LON W 73:33:xx.xxx27 5 331 32 HGT +84.80 m (MSL)29 20 212 3530 10 34 33ELEV MASK 5 deg-------------------------------------------------------------------------------Command CompleteAnd that one too :Code:UCCM-P > STATus- UCCM Slot STATE -1-1. #Now ACTIVE STATUS ---------------- 1-2. #Before ACTIVE STATUS ------------- [Master Holdover]2-1. #Reference Clock Operation -------- [Not Used]2-2. #Current Reference Type ----------- 2-3. #Current Select Reference --------- [GPS 1PPS]2-4. #Current Reference Status --------- [Good Accuracy & Stable]#GPS STATUS ----------------------- #Priority Level ------------------- [LINK > GPS]#ALARM STATUS#H/W FAIL ---------- [ LINK ]3-1. PLL STATUS ------------------------ 3-2. Current: PLL MODE ----------------- [NORMAL 2 MODE]Command CompleteIt's interesting, it says "UCCM slot" so UCCM is probably the product name, and it was used in slots, which apparently could be linked together for redundancy, probably through the ribbon cable connector which can be seen on the PCB picture above.There is also a GPS-specific status command :Code:UCCM-P > POSSTATus-----------------------------------------------------------------------------11/24/2015 19:11:26-----------------------------------------------------------------------------Position : LAT(N 45:29:xx.xxx) LON(W 73:33:xx.xxx) H(84.80 m MSL)-----------------------------------------------------------------------------Geometry : PDOP(0.0) HDOP(0.0) VDOP(0.0)-----------------------------------------------------------------------------Channel Statusnum of visible sats > 11num of sats tracked > 10------ Receiver Channel State ------CH 0 > SateID(5) TrackMode(pos avail) SigValue(39)CH 1 > SateID(13) TrackMode(pos avail) SigValue(40)CH 2 > SateID(15) TrackMode(pos avail) SigValue(44)CH 3 > SateID(18) TrackMode(pos avail) SigValue(41)CH 4 > SateID(20) TrackMode(pos avail) SigValue(41)CH 5 > SateID(21) TrackMode(pos avail) SigValue(40)CH 6 > SateID(24) TrackMode(pos avail) SigValue(35)CH 7 > SateID(27) TrackMode(pos avail) SigValue(36)CH 8 > SateID(29) TrackMode(pos avail) SigValue(36)CH 9 > SateID(30) TrackMode(pos avail) SigValue(33)CH 10 > SateID(0) TrackMode(code search) SigValue(0)CH 11 > SateID(0) TrackMode(code search) SigValue(0)-----------------------------------------------------------------------------Rcvr Status(2) :-----------------------------------------------------------------------------Antenna Voltage: 4794 mV, Antenna Current: 10 mA-----------------------------------------------------------------------------Command CompleteAnd the best one, the timing loop status :Code:UCCM-P > DIAGnostic:LOOP?-------------------------------------------------------------------------------11/24/2015 19:12:19-------------------------------------------------------------------------------LOS MEAS NCO STATUS WEIGHT PBUC FBUC DBUC LBUC IBUC G M TC-------------------------------------------------------------------------------0: 1 0.000e+00 0.000e+00 0x07AC 0 700 700 0 0 2 2 4 291: 1 0.000e+00 0.000e+00 0x068C 0 700 700 0 0 0 2 14 226GPS: 0 -3.037e-08 -7.041e-09 0x0000 1 ---- 1000 1000 ---- ---- 3 6 31-------------------------------------------------------------------------------freq cor = -7.041106e-09phase cor = -2.000000e-11gps phase = 2.033333e-08temp cor = -3.383123e-11Command CompleteIf anybody can help me make sense of that data, please feel free to do so ! I understand 0 and 1 are probably inputs to daisy chain the units so I'm not very interested in these, but what's MEAS (measured phase noise ??), NCO (??), and the TFOM and FFOM saw in the first status command above ? Any other information ? Anyone knows what kind of precision I can expect from that kind of GPSDO ? I don't care about alignment of the frequency output and PPS output to the UTC second but I care about frequency drifts (which should be 0 long term, but what about short term ?).It's definitely a very good and useful lab instrument, I used it to calibrate a HP 5334A counter. Build one too !

author: TheSteve
author_rank: Unknown
timestamp: November 24, 2015, 09:55:33 pm
content: Excellent post - your box is very similar to mine but I used the Trimble equivalent model. Mine is also mounted inside a Hammond box.I used the proper connector pigtails with mine but for someone looking to save even more money you could solder the coax direct to the bottom of the Trimble board and then direct to chassis mount BNC etc connectors.

author: Brainbox
author_rank: Contributor
timestamp: November 29, 2015, 08:31:53 am
content: First, my name is Ko and I am new in this group.I bought one of those Trimble boards from EBay and was looking for some information about this device.A first inspection of the board learned me that one capacitor came lose frome the board and was only connected by one leg.The seller made his excuses and I became a partial refund for this.Because of the complete lack of info from the seller I had to find out everything by myself.Thanks to Your postings I got it to work and now building a nice enclosure around it.There it was that someting strange showed up.Without the case it works fine, but build into the metal housing the ouput changed dramatically.Taking it out of the enclosure output changed to normal again.I found that the metal pads around the four mounting holes are not all connected to ground, but only two of them.Now I mounted the two other pads with nylon screws to isolate them and that seems to solve the problem.To @Uski; I found that the MACT switch forces it to generate an output, even with no antenna attched.So it seems to mean Manual_Activate and shows a alternating red and green activity LED by doing this.

author: Theboel
author_rank: Frequent Contributor
timestamp: December 01, 2015, 11:01:04 pm
content: Hello,do you have manual for your symetricom UCCM board ?the price is very appealing but I like to know if it posible to extract NMEA data from this board.Thank You

author: Vgkid
author_rank: Super Contributor
timestamp: December 01, 2015, 11:44:58 pm
content: Thanks for the post, I'm contemplating buying one of these modules. What is the main connector pinout?

author: TheSteve
author_rank: Unknown
timestamp: December 02, 2015, 05:06:42 am
content: I have not found or seen any official documentation for this board or the Trimble equivalents.(you can google for Trimble 63090 or 73090)You can enable a once per second string but it is hex data string, not NMEA data.As Brainbox mentioned the 4 mounting holes are not all ground - one of them is connected to the 5 volt regulator.The M-act button does manually enable the 10 MHz output even if no GPS lock has been achieved. In the case of the my Trimble which has been running for months constantly it is very accurate in the short term from a cold start. With no GPS connected after the oven is warm it is currently within 4 mHz of proper 10 MHz. So if you had to take the unit out of the lab and just needed a quick reference it would do quite nicely even without GPS lock.

author: uski
author_rank: Frequent Contributor
timestamp: December 03, 2015, 06:07:48 am
content: Hi everybody !Sorry for the lack of replies from me, I didn't see I wasn't subscribed to the thread !Quote from: Brainbox on November 29, 2015, 08:31:53 amI had a similar problem. Those boards are probably scrap yard pulls and have probably seen pretty bad days.It's a very good thing to inspect them before powering them up and to watch out for magic smoke at first power up (damage can often be limited if power is turned off quickly in case of apparent issue).Quote from: Brainbox on November 29, 2015, 08:31:53 amGlad it helped, let me know if you have more specific questionsQuote from: Brainbox on November 29, 2015, 08:31:53 amI used adhesive nylon standoffs everywhere so I didn't know that. Thank for the info, it should help othersQuote from: Brainbox on November 29, 2015, 08:31:53 amGreat, thanks !Quote from: Theboel on December 01, 2015, 11:01:04 pmThe official documentation of the Furuno receiver used shows that it uses a "NMEA like" protocol. That's probably standard NMEA with additional proprietary messages.What application do you have in mind ? If you want to use it as a GPS receiver, I'd say, just get a dedicated GPS receiver. Unless you need a low jitter PPS output, you can get a cheap GPS receiver on eBay. If you want a more precise PPS output, then yes, you need a timing GPS receiver like this one. There is the good uBlox LEA-6T for this, or even the newer (multi-GNSS) LEA-8T.Quote from: Vgkid on December 01, 2015, 11:44:58 pmI have absolutely no ideaI didn't connect anything to it. I connected the +5V input to the fuse directly and to ground, I guessed their location from looking at the power supply layout.The colorful ribbon you see if for the LEDs, I soldered the wires on the back of the PCB to each LED. The ribbon is not connected to the main flex connector which has tens of pins.The power supply is also connected to the main ribbon connector.There are definitely more possible options when using the main connector, specifically linking several of these boards together to get redundancy, but you'd have to find the pinout.If you want to try to contact Symmetricom to get the info, feel free to do it and share the result !Quote from: TheSteve on December 02, 2015, 05:06:42 amThat's a pretty good info. I guess it stores OCXO calibration data in some kind of NVM to make it ready for a cold start.I used my GPSDO today to calibrate other equipment. It's really a useful piece of hardware.I like your case - you're right it looks pretty similar to mine !

author: TheSteve
author_rank: Unknown
timestamp: December 03, 2015, 06:16:25 am
content: Ran my Trimble for 24 hours without GPS - it did very well and was still 4 mHz or less from my other GPS reference. In fact when I connected the GPS antenna a much larger error was introduced for quite a while as it re-synchronized. If anything the OCXO is over-controlled by software and made less stable in the short term. This isn't generally an issue as I leave it running 24/7. I've wanted to order the Symmetricom version to compare them for quite some time but haven't found an extra 50 dollars to throw at it as I already have two GPSDO's. When I bought my Trimble they were under 50 dollars shipped on ebay - for now the Symmetricom at under 50 is the best buy.

author: Deathwish
author_rank: Unknown
timestamp: December 03, 2015, 06:32:35 am
content: I'm still waiting for my symetricon to arrive, I think it lost its GPS bearings between China and the UK

author: Deathwish
author_rank: Unknown
timestamp: December 03, 2015, 07:32:07 am
content: http://www.ko4bb.com/manuals/81.156.83.21/Furuno_GT8031_Protocol_Specification_Rev1.pdfhttp://www.ko4bb.com/manuals/81.156.83.21/Furuno_GT8031_Hardware_Specification_2005.04.28.pdf

author: f1rmb
author_rank: Regular Contributor
timestamp: December 03, 2015, 08:36:55 pm
content: Hi,I'm also building a GPSDO using this Symmetricom card.Today I probed the Furuno pins to get the NMEA frames (Pin#2, next to the square pad one). So that's great.But, since I want to use a GPS display module developed by another Ham (F4CTZ:http://www.f4ctz.fr/?page_id=692), but the little problem with this is that NMEA frames doesn't have checksum field.I've currently modified the source code of the GPS display module to handle that kind of frames, but I have to wait for a friend to reflash the PIC.Cheers.---Daniel

author: Macbeth
author_rank: Super Contributor
timestamp: December 10, 2015, 09:20:52 pm
content: Just to let us Symmetricon fanboys know, the MACT button does indeed enable the 10MHz output without a GPS signal. This is also possible using the serial commandDIAGnostic:OUTPut ON|OFF

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 11, 2015, 08:04:04 pm
content: Received mine yesterday, same seller I guess because it also included the oilhttp://www.ebay.com/itm/121761130751Also ordered this antenna from the same seller, it works ok:http://www.ebay.com/itm/111734469938And a handful of pigtails from here:http://www.ebay.com/itm/281313869844Looks like it lived on this building from October 2011 to at least (last log entry) April 2014:https://www.google.com/maps/@35.361216,139.6222302,42m/data=!3m1!1e3I wonder if the seller did test these, there's no evidence in the log that it was ever powered on between the building and my house.Code:L485:1980-01-06 00:00:02:Power OnL486:1980-01-06 00:00:36:Survey mode startedL487:1980-01-06 00:01:48:Time set to GPSL488:2014-04-24 01:45:50:Time set to GPSL489:2014-04-24 01:49:04:GPS lock startedL490:2014-04-24 03:44:48:Position hold mode startedL491:2014-04-24 03:44:48:Lat: N,+35,+21,+40.5L492:2014-04-24 03:44:48:Long: E,+139,+37,+20.4L493:2014-04-24 03:44:48:Height: +67.5L494:1980-01-06 00:00:02:Power OnL496:1980-01-06 00:00:36:Survey mode startedL497:1980-01-06 00:07:54:Time set to GPSL498:2015-12-11 19:10:14:Time set to GPSL499:2015-12-11 19:11:11:GPS lock startedInitial current at 5V was 1.8A, dropping to 0.8A after the OCXO warms up.Now to find a nice spot for the antenna and put it in a box...Edit: The forum doesn't like links with a ! in it, so if you want to see the building copy the full link to your browser or click 'earth'.

author: Deathwish
author_rank: Unknown
timestamp: December 12, 2015, 09:09:22 am
content: Mine is well overdue from him, ordered the same antenna from another seller, so glad to hear it works ok.

author: davebb
author_rank: Frequent Contributor
timestamp: December 12, 2015, 11:02:39 pm
content: Hi I have just ordered the symetricon and the trimble gpsdo from the same seller,i hope they work ok,I am going to lock my kenwood ts-2000 and my 4 meter transverter and test gear with then,how long do these take to settle at 10.000000MHZ,and what is the max voltage it can be run from?what is the sensitivity like from the gps rx,and what number of sats do you need to be receiving for good 10mhz stability,what size is the unit so I can start looking for a box to fit it in,Thanks Dave 2E0DMB

author: Macbeth
author_rank: Super Contributor
timestamp: December 12, 2015, 11:40:48 pm
content: The Symmetricom and the Trimble versions of these should run at >5V-5.5V with a 2A supply no problem, PSU lead losses accounted for. Don't go too much over 5V as the supply is directly sent (minus a diode drop) to the external antenna, which are usually 3-5V.The Symmetricom has a 12V OCXO and uses a TI PTN4050C boost converter while I understand the Trimble uses a 5V OCXO so doesn't need this.My Symmetricom boost converter was DOA, as was the missing MCX antenna socket and the broken MACT switch.The seller gave me the runaround and eventually pretended to send me a replacement board out and try and get me to "wait for it" one week after the ebay dispute timeout period. Of course with my simple notification that I would involve ebay he refunded me at the 11th hour.I'm now using a cheap XL6009 instead. There are some other issues with starting this Symmetricom board with less than 1.7A too...

author: davebb
author_rank: Frequent Contributor
timestamp: December 13, 2015, 11:14:41 am
content: Hi thanks for the info,i will post when I receive them,Thanks Dave 2E0DMB

author: davebb
author_rank: Frequent Contributor
timestamp: December 13, 2015, 03:07:09 pm
content: Offline f1rmbRegular Contributor*Posts: 122Country: frView ProfilePersonal Message (Offline)Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)« Reply #10 on: December 04, 2015, 07:36:55 AM »QuoteHi,I'm also building a GPSDO using this Symmetricom card.Today I probed the Furuno pins to get the NMEA frames (Pin#2, next to the square pad one). So that's great.But, since I want to use a GPS display module developed by another Ham (F4CTZ:http://www.f4ctz.fr/?page_id=692), but the little problem with this is that NMEA frames doesn't have checksum field.I've currently modified the source code of the GPS display module to handle that kind of frames, but I have to wait for a friend to reflash the PIC.Cheers.---DanielHi DanielCould you please The modified Hex code/File as I would like to build this display,you say the output is on pin 2 is that in rs232 or TTL level?Thanks Dave 2E0DMB

author: f1rmb
author_rank: Regular Contributor
timestamp: December 13, 2015, 03:23:52 pm
content: Quote from: davebb on December 13, 2015, 03:07:09 pmYeah, sure.The level is TTL.On the display module, you have to change two components:T1 from 2N2222 to MMBT2907 (or equivalent), and the base resistor R3, from 10k to 4k7.Cheers.---Daniel

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: December 13, 2015, 04:23:21 pm
content: Those links are not connecting for me ?Quote from: Deathwish on December 03, 2015, 07:32:07 am

author: f1rmb
author_rank: Regular Contributor
timestamp: December 13, 2015, 04:25:25 pm
content: Hi,http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=02_GPS_Timing/FurunoworksCheers.---Daniel

author: davebb
author_rank: Frequent Contributor
timestamp: December 13, 2015, 04:35:24 pm
content: Hi DanielThanks for that,I will Wait until I have the unit,have you made your display?would I be able to use a different display as I would like to make it on vero board,This is one of the things I am going to use the 10mhz ref for,http://www.vk3hz.net/XRef/XRef_Home.htmlI have the one for the kenwood ts-2000 and I had him make me a 10mhz to 42mhz unit with a tcxo for when the 10mhz ref is not plugged in for my 4 meter transverter, the units took about 1 week to arrive in the ukThanks Dave 2E0DMB

author: f1rmb
author_rank: Regular Contributor
timestamp: December 13, 2015, 04:38:48 pm
content: Hi Dave,No, I didn't etched the PCB, with 2 Ham friends we ordered the last 3 kits from F4CTZ some time ago.Maybe you could ask him if he have some new kits available.Cheers.---Daniel

author: Macbeth
author_rank: Super Contributor
timestamp: December 13, 2015, 05:54:24 pm
content: Quote from: uski on November 24, 2015, 09:44:48 pmI just found this one.TFOM (Time Figure of Merit) is the accuracy of the 1 PPS signal, with 0 < 1ns, 1= 1 to 10 ns, 2 = 10 to 100 ns, 3 = 100ns to 1us, ... 9 > 1msFFOM (Frequency Figure of Merit) is the stability of the 10MHz signal. 0 = PLL stable, 1 = stabilizing, 2 = holdover, 3 = unlocked (do not use as 10MHz out of spec)You can use the commands SYNC:TFOM? and SYNC:FFOM? to get a description of the current state.e.g.Code:UCCM-P > sync:tfom?10-100 nsCommand CompleteUCCM-P > sync:ffom?PLL stabilizedCommand CompleteI'm trying to find other stuff and can't find the manual for this particular unit, but other symmetricom and HP GPSDO manuals seem to have similar information in them.

author: davebb
author_rank: Frequent Contributor
timestamp: December 13, 2015, 07:25:55 pm
content: Hi I did email F4CTZ:http://www.f4ctz.fr/?page_id=692),about the nmea v2 gps display kit, and I got a reply from him saying that if 10 or more people want to buy the display kit he will produce the kit again,i have asked for the price of the kitI will post when I get the infoThanks Dave 2E0DMB