[time-nuts] Efratom/Datum GPSDO GPS-FC

Vlad time at patoka.org
Mon Jun 1 09:38:11 EDT 2015


Paul,

For the testing purpose, I connecting GPS-FC to my GPS Distribution Amp. 
This is why antenna has disconnected on the picture. When I testing this 
unit - i connecting coax to it.
Yesterday, I connected TTL serial to its Motorola Module, to see what is 
going on there. Here is screenshots:

http://www.patoka.ca/OCXO/Moto1.JPG
http://www.patoka.ca/OCXO/Moto2.JPG

I left that unit up and running overnight, and even after that its still 
not show me real location and number of "visible" satelites is still 
"zero".


Regards,
Vlad

On 2015-05-31 21:50, paul swed wrote:
> Quite difficult to see. But it appears the gps antenna cable is just
> hanging there not connected to what I presume would be a antenna.
> Regards
> Paul
> WB8TSL
> 
> On Sun, May 31, 2015 at 4:47 PM, Bob Camp <kb8tq at n1k.org> wrote:
> 
>> Hi
>> 
>> If you look at the pictures you can see the oscillator they are using 
>> for
>> the 10 MHz. At least as far as I can see
>> it’s markings look like those of a VC TCXO. If you mount the device
>> outdoors (as you must to get it to work) there
>> will be a lot of temperature swings. In if the little oscillator *is* 
>> an
>> OCXO, it’s not a fancy one. Between the
>> simple oscillator and the outdoor location, you are unlikely to get 
>> very
>> good performance out of the unit.
>> 
>> The Oncore in this device has many of the same issues as ones we have
>> discussed in other GPSDO’s. The
>> design of the one in your gizmo is now approaching 20 years old. The
>> interface strings are well documented
>> and you should be able to tap into the module’s i/o stream to see 
>> what’s
>> going on. I would recommend tacking
>> a TTL to USB converter onto it and letting a terminal program show you
>> what is happening.
>> 
>> Bob
>> 
>> 
>> > On May 31, 2015, at 11:58 AM, Vlad <time at patoka.org> wrote:
>> >
>> >
>> >
>> > Hello,
>> >
>> > Some time ago, I got Efratom/Datum GPS-FC item. The apparatus itself
>> looks like good quality weather-proof aluminium case with embedded GPS
>> antenna. It has only one connector. That connector is using to supply 
>> the
>> power to the unit and as well to get 10Mhz signal from it.
>> >
>> > Here is the sticker inside of the devices:
>> >
>> > http://www.patoka.ca/OCXO/GPS-FC-LBL.JPG
>> >
>> > I tried to play with this device, however all my attempts to get 10 Mhz
>> from it has failed.
>> >
>> > Here is how its looks inside:
>> >
>> > http://www.patoka.ca/OCXO/GPS-FC-PCB.JPG
>> >
>> >
>> > AFAIK, there is Motorola Oncore GPS. I checked the 1PPS signal from that
>> module and its looks good - I see the 1PPS on my scope.
>> > Also I did check on TP4 on PCB. Looks like its an output from 10Mhz
>> VTCXO. And I see the sine on the scope.
>> >
>> > I tried to contact Microesemi to obtain some service manual or even
>> schematic for this unit, but unfortunately its not an option. 
>> Microsemi
>> sent me only this manual:
>> >
>> > http://www.patoka.ca/OCXO/GPS-FC-Manual.pdf
>> >
>> >
>> > Its appeared this units out of support for long period of time. So, I
>> would ask if anybody knows anythings about it ? Especially I would be
>> interested about what to measure/expect on control points on PCB. I 
>> still
>> hope its repairable. Thanks in advance !
>> >
>> >
>> >
>> > --
>> > WBW,
>> >
>> > V.P.
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-- 
WBW,

V.P.



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