Author Topic: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver) (Read 421660 times)

davebb · « **Reply #50 on:** December 17, 2015, 10:27:16 am »

Yes sorry I did mean 18f2620 DIP
Thanks Dave

f1rmb · « **Reply #51 on:** December 17, 2015, 10:32:46 am »

Quote from: davebb on December 17, 2015, 10:27:16 am

Yes sorry I did mean 18f2620 DIP
Thanks Dave

Ah, okay. Well, I have no clue about your problem. Configuration are stored inside the hex.
Is your pic programmer recognize the chip? Are you able to erase it?

Cheers.
---
Daniel

davebb · « **Reply #52 on:** December 17, 2015, 02:30:40 pm »

Hi Dan
Yes I have done both,i will play with it more when the display arrives,like I say you have done a brilliant job on your unit,
The only difference is that I am usinga S/P DIL chip not a smt device,
Thanks Dave 2E0DMB

Deathwish · « **Reply #53 on:** December 21, 2015, 11:55:14 am »

Gave up waiting for mine to come,so demanded a refund, went to aliexpress and got a trimble for £46.

jackenhack · « **Reply #54 on:** December 21, 2015, 05:03:05 pm »

Quote from: Macbeth on December 14, 2015, 02:11:04 am

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! )

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!

I've just finished building a Raspberry Pi Stratum-1 NTP server. I'm currently using a U-Blox 7M GPS module, because my Trimble GPSDO's 1 PPS output have too short output pulse width.

Seems like the PPS kernel driver needs a longer pulse to work. But I'm going to build this to lengthen the pulse, because I want to use the Trimble's output.

This will give approximately 250ms pulse which should be enough.

Macbeth · « **Reply #55 on:** December 21, 2015, 07:30:27 pm »

@jackenhack. Thanks, yes the pulse width is very narrow. Thanks for that, I probably would have wasted hours debugging it

jackenhack · « **Reply #56 on:** December 21, 2015, 08:04:34 pm »

Quote from: Macbeth on December 21, 2015, 07:30:27 pm

@jackenhack. Thanks, yes the pulse width is very narrow. Thanks for that, I probably would have wasted hours debugging it

Getting the 74HC123 tomorrow, so I'll keep you posted on if it works.

Added a rudimentary display to the NTP server so I could get the time, and also get some status so I know when the network goes down and it switches to GPS/PPS only. It's no Nixie clock but it's something.

https://dl.dropboxusercontent.com/u/261736/Images/ntp-server-display.mov

Macbeth · « **Reply #57 on:** December 21, 2015, 11:09:09 pm »

But are you taking into account the 1/4 second delay by triggering on the falling edge?

I quite like my earlier alluded to PTIME:TCODE? serial query, and then I would use an interrupt rather than polling to snatch that 1PPS just within that 10us period. Also, don't forget you have to program in the antenna delay too - use GPS:REF:ADELAY <seconds>, e.g. 25E-9 for 25ns (5 meters cable) - ok that would help with the 10MHz more so

But maybe the TOD output takes account of a lot of this. Like it should take account of baud rate, etc. No exact documentation to go on, so

jackenhack · « **Reply #58 on:** December 22, 2015, 09:28:18 pm »

Quote from: Macbeth on December 21, 2015, 11:09:09 pm

But are you taking into account the 1/4 second delay by triggering on the falling edge?

I quite like my earlier alluded to PTIME:TCODE? serial query, and then I would use an interrupt rather than polling to snatch that 1PPS just within that 10us period. Also, don't forget you have to program in the antenna delay too - use GPS:REF:ADELAY <seconds>, e.g. 25E-9 for 25ns (5 meters cable) - ok that would help with the 10MHz more so

But maybe the TOD output takes account of a lot of this. Like it should take account of baud rate, etc. No exact documentation to go on, so

There shouldn't be a delay. The circuit resets and waits for the next rising edge. You can adjust the time with R1 and C1. With these values, you should get about 250ms.

Yup, have measured the length of my cable, even checking the speed the HUBER+SUHNER cable propagates signals and added the delay. :-)

Deathwish · « **Reply #59 on:** December 23, 2015, 05:09:41 pm »

does anyone have the pin outs for that symmetricom units ribbon cable

davebb · « **Reply #60 on:** December 24, 2015, 01:48:01 pm »

Hi Steve
I received my trimble from China the same as yours Today 12 days to the uk,
Can You please tell me how to get the list of commands
I have treid sending ?
but that is not recognised,i can send STAT and that works,
also when I powered it on it does output the 10mhz,i read I can change this to only output when gps is active?
and how do I change the ELV from 5deg on start up survey
Thanks Dave 2E0DMB

davebb · « **Reply #61 on:** December 24, 2015, 03:32:33 pm »

I can See most of the commands for the Symmetricom GPSDO / 10MHz, work
Dave 2E0DMB

Vgkid · « **Reply #62 on:** January 04, 2016, 10:13:50 pm »

So i bought 2 units, but they were not described as in good shape.
Lets see how they are, when they arrive.

davebb · « **Reply #63 on:** January 06, 2016, 09:02:04 pm »

Hi The Trimble I orded came on the 24/12, I am still waiting for my Symmetricom GPSDO / 10MHz that I orded 2 days after the trimble,
the ones I orded were not advertised as working just good condition,
the trimble works fine but I did fined a solder bridge mod to reduce the output level,that I removed and now is working very well,i just need to get the antenna outside with some lmr400 coax,
I also have picked up a Working HP 4port N-type amp with 3 ports DC blocked from china that came in 1week
Dave 2E0DMB

TheSteve · « **Reply #64 on:** January 06, 2016, 09:47:22 pm »

LMR400 - you're going all out! I save the good stuff for my antenna's that connect to the ham rigs. I have two Trimble GPS antennas mounted on my tower, both use surplus RG62 coax - yep it is 75 ohms and introduces an impedance mismatch but there is plenty of signal. It seems it was even a recommended practice by Trimble in the past as a cost effective feed line choice.

btw, hope your IC7000 sale goes well(I'm on the mailing list)

davebb · « **Reply #65 on:** January 06, 2016, 11:17:30 pm »

Hi Steve
Yes a bit over the top, I got 100m of ultraflex for a good price,i also have about 70m of 9913 I will use that,
I was just playing the u-blox 6m was getting 14 sats,and the trimble was getting 5-6,that was both running of the same inside antenna
Dave 2E0DMB

edpalmer42 · « **Reply #66 on:** January 06, 2016, 11:33:21 pm »

Quote from: TheSteve on January 06, 2016, 09:47:22 pm

LMR400 - you're going all out! I save the good stuff for my antenna's that connect to the ham rigs. I have two Trimble GPS antennas mounted on my tower, both use surplus RG62 coax - yep it is 75 ohms and introduces an impedance mismatch but there is plenty of signal. It seems it was even a recommended practice by Trimble in the past as a cost effective feed line choice.

btw, hope your IC7000 sale goes well(I'm on the mailing list)

Hi Steve,

Actually, RG62 (was that a typo?) is 93 ohm cable, but since it works I guess it doesn't matter! You are correct that Trimble recommends RG6 cable. In the manual for the Thunderbolt they basically say "Yes, there's a mismatch but it doesn't matter so quit whining and use it!" or words to that effect.

The Thunderbolt actually has an F connector for the antenna to make it easy to use CATV cable.

Ed

davebb · « **Reply #67 on:** January 06, 2016, 11:37:35 pm »

Hi Steve
I am surprised The 7000 has not sold so far,i mite change some of the photos,I just wanted to show power output on HF/VHF/UHF as I know They Can Have problems,
I can not believe some people buy radios on ebay when sellers just say that it switches on and it all lights up
and that is the only test that they can do,and the radio sells for a good working price
Dave 2E0DMB

davebb · « **Reply #68 on:** January 07, 2016, 04:44:42 pm »

My Symmetricom GPSDO / 10MHz Came today,its not good news+
I can see 3 component's have been ripped off the board c108,c52,and u25
,The Main problem is When U25 was ripped off it has damaged The Tracks on the pcb
if anyone can tell me what Value The caps are,and What U25 is and if anyone can tell me were it is wired to
as I would like to fix this
Thanks Dave 2E0DMB

Macbeth · « **Reply #69 on:** January 07, 2016, 05:05:36 pm »

U25 is the same as U24 labelled Z04B on mine

The caps I can't get any valid in circuit measurements, sorry.

davebb · « **Reply #70 on:** January 07, 2016, 05:46:50 pm »

Hi Thanks Macbeth
That helps a lot
this is what I found,that it is a inverter, one of the tracks that's missing is not connected as I found out on y=the data sheet
NC7SZ04P5X

Thanks Dave

TheSteve · « **Reply #71 on:** January 07, 2016, 05:49:50 pm »

Quote from: edpalmer42 on January 06, 2016, 11:33:21 pm

Quote from: TheSteve on January 06, 2016, 09:47:22 pm
LMR400 - you're going all out! I save the good stuff for my antenna's that connect to the ham rigs. I have two Trimble GPS antennas mounted on my tower, both use surplus RG62 coax - yep it is 75 ohms and introduces an impedance mismatch but there is plenty of signal. It seems it was even a recommended practice by Trimble in the past as a cost effective feed line choice.

btw, hope your IC7000 sale goes well(I'm on the mailing list)

Hi Steve,

Actually, RG62 (was that a typo?) is 93 ohm cable, but since it works I guess it doesn't matter! You are correct that Trimble recommends RG6 cable. In the manual for the Thunderbolt they basically say "Yes, there's a mismatch but it doesn't matter so quit whining and use it!" or words to that effect. The Thunderbolt actually has an F connector for the antenna to make it easy to use CATV cable.

Ed

A typo indeed - that 2 got in there somewhere. I am using RG6 cable.

davebb · « **Reply #72 on:** January 09, 2016, 04:14:27 pm »

I Have fitted a new inverter and played fitting different value caps in were the broken ones, and found another broken one C103 ,still not working
my cat is trying to help as well
Dave 2E0DMB

Vgkid · « **Reply #73 on:** January 09, 2016, 04:59:39 pm »

Cute cat

davebb · « **Reply #74 on:** January 09, 2016, 05:53:06 pm »

Hi Yes he is a good boy, always wants to see what I am doing,He will only do what he wants to do
Hi can be a pain,but I would not change Him and he is very talkative
Thanks Dave


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Author Topic: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver) (Read 421660 times)

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