Author Topic: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)  (Read 174499 times)

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Offline uski

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #25 on: December 14, 2015, 07:17:35 AM »
Hi,

...and the TFOM and FFOM saw in the first status command above ? Any other information ?
I 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 > 1ms
FFOM (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: [Select]
UCCM-P > sync:tfom?
10-100 ns
Command Complete
UCCM-P > sync:ffom?
PLL stabilized
Command Complete

I'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.

That's great info, many thanks !

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 kit
I will post when I get the info

What's the point of this ? I mean, this is a GPSDO. I think the stats you'd want would be about timing related stuff (TFOM, FFOM, ...), OCXO status, PLL status, maybe GPS time, but why display lat/long ?

I started a display PCB for my GPSDO. It's very low priority so not sure I'll finish it, but if I do i'll let you all know. Basically it's just a PCB with a 4x20 LCD and a MCU.
 

Offline f1rmb

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #26 on: December 14, 2015, 08:46:17 AM »
Hi,

...and the TFOM and FFOM saw in the first status command above ? Any other information ?
I 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 > 1ms
FFOM (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: [Select]
UCCM-P > sync:tfom?
10-100 ns
Command Complete
UCCM-P > sync:ffom?
PLL stabilized
Command Complete

I'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.

That's great info, many thanks !

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 kit
I will post when I get the info

What's the point of this ? I mean, this is a GPSDO. I think the stats you'd want would be about timing related stuff (TFOM, FFOM, ...), OCXO status, PLL status, maybe GPS time, but why display lat/long ?

I started a display PCB for my GPSDO. It's very low priority so not sure I'll finish it, but if I do i'll let you all know. Basically it's just a PCB with a 4x20 LCD and a MCU.
Think about Ham activities, in  the field, really useful to have such informations. Also the F4CTZ display can help you tracking the sun and moon.
 

Offline Theboel

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #27 on: December 14, 2015, 11:49:30 AM »
I like to have display for my GPSDO box because I like to see the signal strength from the satellite I receive for some situation like difficult outdoor antenna installation it will very helpful.
 
 

Offline Macbeth

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #28 on: December 14, 2015, 01:11:04 PM »
Yes, the LAT/LON seem to be a pretty minor thing to display compared to GPS or UTC time and date. Lock, 10MHz, 1PPS status etc is more important still. These things are not meant to be mobile but in a fixed location. Any old GPS could be used for a LAT/LON position. Once a survey is complete that LAT/LON will never change display (hopefully - but I think even earthquakes, landslides, sinkholes will take a long time to correct!  :-DD )

Now I still have to make a Nixie clock and this thing is ideal - a combined desk clock, Stratum-1 (a Ras Pi) NTP server for my network, and distributed 10MHz and 1PPS too all in one box  :-+

I warn you all, my ebay last second (microsecond?) sniping will reach a whole new level of evil I tell you! automated by my Stratum-1 Raspberry Pi Bidsniper! >:D  :-DD
 

Offline Deathwish

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #29 on: December 14, 2015, 01:31:31 PM »
I warn you all, my ebay last second (microsecond?) sniping will reach a whole new level of evil I tell you! automated by my Stratum-1 Raspberry Pi Bidsniper! >:D  :-DD

And then at the last picosecond the internet fell out, muahaha
Electrons are typically male, always looking for any hole to get into.
trying to strangle someone who talks out of their rectal cavity will fail, they can still breath.
God hates North Wales, he has put my home address on the blacklist of all couriers with instructions to divert all parcels.
 

Offline davebb

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #30 on: December 14, 2015, 01:34:02 PM »
Hi you could fit a cheap Bluetooth board on to it and use a Bluetooth gps app on your phone
Dave 2E0DMB
 

Online TheSteve

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #31 on: December 14, 2015, 01:55:02 PM »
Yes, the LAT/LON seem to be a pretty minor thing to display compared to GPS or UTC time and date. Lock, 10MHz, 1PPS status etc is more important still. These things are not meant to be mobile but in a fixed location. Any old GPS could be used for a LAT/LON position. Once a survey is complete that LAT/LON will never change display (hopefully - but I think even earthquakes, landslides, sinkholes will take a long time to correct!  :-DD )

Now I still have to make a Nixie clock and this thing is ideal - a combined desk clock, Stratum-1 (a Ras Pi) NTP server for my network, and distributed 10MHz and 1PPS too all in one box  :-+

I warn you all, my ebay last second (microsecond?) sniping will reach a whole new level of evil I tell you! automated by my Stratum-1 Raspberry Pi Bidsniper! >:D  :-DD

You assume ebay has accurate time, - good luck with that.

btw, here is a scope shot showing 24 hours with infinite persistence enabled comparing my Nortel GPSDO and my Trimble UCCM. So either they are both bang on 10 MHz or both incorrect. A good thing overall as the one BG7TBL GPSDO was not really running at 10 MHz.

Also I have checked on my Trimble and have never seen lower then 10-100 nsec for the TFOM

UCCM >SYNChronization:TFOMerit?
10-100nsec
Command complete
« Last Edit: December 14, 2015, 02:07:02 PM by TheSteve »
VE7FM
 

Offline Vgkid

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #32 on: December 14, 2015, 02:07:44 PM »
Hi you could fit a cheap Bluetooth board on to it and use a Bluetooth gps app on your phone
Dave 2E0DMB
your best bet would be to look into one of the ublox alternatives. The 8m/n receivers are much more powerful than the Furuno in the Symmetricom unit. The Furuno is a 16ch unit, that can track 12. The Ublox 8 series is a 72 ch gps/glonass/beidou receiver.
If you own any North Hills Electronics gear, message me.
 

Offline davebb

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #33 on: December 14, 2015, 03:06:21 PM »
Hi I meant to use your phone or tablet as a display not as a gps source
Dave 2E0DMB
 

Offline davebb

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #34 on: December 14, 2015, 03:16:20 PM »
Hi Steve can you test one of those against the BG7TBL GPSDO,
Dave 2E0DMB
 

Online TheSteve

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #35 on: December 14, 2015, 03:26:02 PM »
Hi Steve can you test one of those against the BG7TBL GPSDO,
Dave 2E0DMB

I would if I had one, only have these two at the moment - just enough to never know which one is better!

btw, I did generate a 10.000000001 MHz signal(referenced to one of the GPSDO's) and feed it into a third channel, it didn't take long to see the error with persistence set to infinite.

I now have a 10.0000000001 MHz signal on channel 3 and will let it run for a while to see the error show up.
« Last Edit: December 14, 2015, 03:35:48 PM by TheSteve »
VE7FM
 

Offline davebb

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #36 on: December 14, 2015, 04:10:53 PM »
Hi Steve I have a  BG7TBL GPSDO with the ublox 6m, so when I get my other ones I will do a test
Dave
 

Online TheSteve

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #37 on: December 14, 2015, 05:25:37 PM »
Here is two hours with the two GPSDO's, the third channel(bottom) is a frequency generator referenced to the top GPSDO outputting 10.000,000,000,1 MHz - error of 100 microHz. So it shows how easy it is to see a small error with the scope over time. The frequency counter is also referenced to the same GPSDO as the frequency generator.


EDIT - added a third picture which is the same configuration as above except the frequency generator has been set to 9.999,999,999,8 MHz which is the approximate frequency of the original BG7TBL GPSDO, elapsed time was only 30 minutes. Within an hour it would just be a purple smear on the screen. So if you do have one this is what you can expect.

btw, with the frequency generator set to 10 MHz exactly there is zero drift as it is referenced to a GPSDO. I think that original BG7TBL GPSDO would drive me nuts - I'd always know it isn't really 10 MHz.

I wish I had the Symmetricom version of the UCCM to compare but I expect it to be similar to the Trimble as they were designed to the same specs for whatever cell system they were installed in.
« Last Edit: December 15, 2015, 04:33:18 AM by TheSteve »
VE7FM
 

Offline davebb

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #38 on: December 15, 2015, 12:49:27 AM »
Hi F4CTZ has got back to me
if 10 kits are orderd the price would be 50 euros and 30-40 kits are orderd price will be 30-35euros that's +P&P
I have orderd the parts to make mine on vero board lcd from china will not need smt connectors,i have the pic SDIP,coming from rs tomorrow,
the bg7tbl gpsdo I have has the 16-4-2015 pcb fitted, last night I pluged in a rs232 Bluetooth serial adapter in to the DB9 nd have been running Bluetooth gps app on my android phone to see the number of sats and levels, and I have found out were I live :)
I am going to wire in a TTL level blutooth adapter to the ublox tx line to be left in the unit,
Dave 2E0DMB
 

Offline f1rmb

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #39 on: December 17, 2015, 07:55:02 AM »
Hi,

@davebb: That sounds great, let us know your progress.

So, I just finished my enclosure.

Cheers.
---
Daniel
 

Online TheSteve

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #40 on: December 17, 2015, 08:08:15 AM »
Looks great - do you have more info on your distribution amplifier?
VE7FM
 

Offline f1rmb

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #41 on: December 17, 2015, 08:11:24 AM »
Looks great - do you have more info on your distribution amplifier?

Thanks ;-)

Yeah, I used the DF9NP's fanout 1:10 schematic, then changed two things. If you're interested, I can provide my schematic, eagle files and so on.

Cheers.
---
Daniel
 

Offline Vgkid

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #42 on: December 17, 2015, 08:23:22 AM »
 :-+ great job.
If you own any North Hills Electronics gear, message me.
 

Offline davebb

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #43 on: December 17, 2015, 08:49:37 AM »
Hi Daniel that looks really good
I fitted a Bluetooth module in the bg7tbl,the range is not very good I have put it on the back pcb panel
I wired it to the TTL tx in on the max3232 so its on the output of the microcontroller so it wont upset anything,

I got my pic16f2620 is/dip but when I try and program it I get configuration error, can you tell me are there any settings I have to change in the configuration of the program ie, oscillator etc
Thanks Dave 2E0DMB
 

Offline davebb

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #44 on: December 17, 2015, 09:10:21 AM »
Hi again Daniel
so is your display wired strait to the TX pin on the gps module
Thanks Dave 2E0DMB
 

Offline Macbeth

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #45 on: December 17, 2015, 10:14:18 AM »
I have to admit I have no real interest in the immediate GPS output of the Furuno, because better engineers than me have sorted that stuff out into the Symmetricom GPSDO with a FFOM of at least 2.

I would like to know what the TOD data packets are, like when you enable TOD EN on SER2. There is also the SER1 output which I haven't probed yet but is most likely the TOD output in binary from what others have stated.

An interesting serial request is PTIME:TCODE? - this is not listed when you issue the ? help command, but is in other Symmetricom documentation.

T1xxxxxxxxtlfrvcc
xxxxxxxx is the date and time of the next 1PPS pulse, referenced to GPS time as number of seconds since 1980/01/06 00:00:00

There can sometimes be a little delay when you issue this command, no doubt to make sure it doesn't respond too early as it is the predicted time of the next 1PPS pulse.

ETA: My ebay bidding sniper wars require such accuracy  :-DD But seriously, I suspect all the banksters "high frequency trading" must rely on this stuff.
« Last Edit: December 17, 2015, 10:18:09 AM by Macbeth »
 

Offline uski

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #46 on: December 17, 2015, 12:03:31 PM »
Looks great - do you have more info on your distribution amplifier?
Yeah, I used the DF9NP's fanout 1:10 schematic, then changed two things. If you're interested, I can provide my schematic, eagle files and so on.

Hi Daniel ! Your box looks awesome, i'm jealous :-+

I could totally use your Eagle files for the splitter too. Please share ! :)
 

Offline f1rmb

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #47 on: December 17, 2015, 07:09:32 PM »
Hi Dave,

Hi Daniel that looks really good
I fitted a Bluetooth module in the bg7tbl,the range is not very good I have put it on the back pcb panel
I wired it to the TTL tx in on the max3232 so its on the output of the microcontroller so it wont upset anything,

I got my pic16f2620 is/dip but when I try and program it I get configuration error, can you tell me are there any settings I have to change in the configuration of the program ie, oscillator etc
Thanks Dave 2E0DMB

It's a PIC18F ;-)

Cheers.
---
Daniel
 

Offline f1rmb

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #48 on: December 17, 2015, 07:11:29 PM »
Hi,

Hi again Daniel
so is your display wired strait to the TX pin on the gps module
Thanks Dave 2E0DMB

Yes, since both are TTL. Pin #1 on J1 connector.

Cheers.
---
Daniel
 

Offline f1rmb

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
« Reply #49 on: December 17, 2015, 07:17:31 PM »
Hi,

Looks great - do you have more info on your distribution amplifier?
Yeah, I used the DF9NP's fanout 1:10 schematic, then changed two things. If you're interested, I can provide my schematic, eagle files and so on.

Hi Daniel ! Your box looks awesome, i'm jealous :-+

I could totally use your Eagle files for the splitter too. Please share ! :)

Happy you like it ;-)

Here they are. Bear in mind that's DF9NP's work, I modified it for my personnal requirements (Symmetricom output level, power supply input voltage and filtering).

Cheers.
---
Daniel
« Last Edit: December 17, 2015, 07:29:42 PM by f1rmb »
 
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