Author Topic: Symmetricom NTS-200 Time Server  (Read 18500 times)

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Offline YetAnotherTechie

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Re: Symmetricom NTS-200 Time Server
« Reply #75 on: February 20, 2020, 08:36:27 pm »
Hello,
I've been following this thread and just have to ask...
I saw on one of the datasheets above that the timing accuracy is at least 150ns plus a few millis once you add the other network overheads. There's been a lot of progress on GPS chipsets in the last 20(!) years, have you considered using a modern timing unit like ublox M8T and say a raspberry pi or similar?
Don't get me wrong, i know and love fixing old gear, but i also consider the performance of the fixed unit and the usefulness of the knowledge i gain repairing it, and to me this units seem like a bad proposition?
 

Offline smgvbest

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Re: Symmetricom NTS-200 Time Server
« Reply #76 on: February 22, 2020, 10:58:37 pm »
I have and use a Pi3 + ublox as a stratum 1 time source with fall back to ntp servers as a Stratum 2 time source.   My usage is in Astronomy and keeping my PC set so that images have a accurate timestamp.

for me this is a fun problem to solve, Just wanted to see if I could do it while learning some reverse engineering techniques.
Sandra
(Yes, I am a Woman :p )
 

Offline acfnews

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Re: Symmetricom NTS-200 Time Server
« Reply #77 on: February 23, 2020, 09:30:09 am »
Hi,

Also totally aware of the (better) possibilities of other hardware. The remote site where the NTS-200 was located also has a newer GPS stratum1 timeserver used in an IoT gateway. The NTS-200 has more emotional value than technical value, and still I think messing around with it is a learning process...

Best regards,

Ron


 

Offline smgvbest

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Re: Symmetricom NTS-200 Time Server
« Reply #78 on: April 04, 2020, 09:04:34 am »
I have not fixed mine yet.
I am convinced until you resolve the incorrect time coming from the P60ARM/GPS you're not going to have a reliable fix.
Problem I have is my EPROM read does not read the 16bit eproms used by this controller nor does the JTAG interface support reading them from what I can tell.   it has a limited JTAG version 1 implementation.
I'm not a JTAG expert but even if I could get a dump of the memory i have no way to write new eproms.   

I did find the AT49F1025 are a pin compatible replacement but are also very hard to find and my programmer does not support them either.   the 8 bit version yes,  not the 16 bit version

Sandra
(Yes, I am a Woman :p )
 

Offline InFoq

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Re: Symmetricom NTS-200 Time Server
« Reply #79 on: December 26, 2020, 07:15:11 am »
I'm wondering if a linux ntpd or other daemon between nts200 and clients can correct the gps epoch correctly.
not a solution for everyone...but it was not too difficult to program NFQUEUE processes in C on my linux (running ntpd client) to do the timestamp offset corrections in each traffic direction.  Turned out simplicity of NTP protocol being self-unaware enough to allow this to work quite well!  Not sure how non-deterministic the OS's NFQUEUE mechanism is, but NTP's PLL corrections should not be much worse than for other worst-case internetworking jitters... E.g. MitM mangling set-top-box protocol:
https://xakcop.com/post/mitm-stb/
« Last Edit: December 27, 2020, 07:55:38 am by InFoq »
 


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