[time-nuts] Efratom/Datum GPSDO GPS-FC
time at patoka.org
Mon Jun 1 00:45:19 UTC 2015
Its definitely VC TCXO. For the tests, I disconnected GPS-FC "embedded"
antenna and connect it to my GPS distribution amplifier. In this case I
could have GPS signal indoor. Its not perfect. But should be enough for
I soldered TTL Serail sniffer to GPS-FC and I got following:
Which, I think, looks like Motorola protocol. And that means the GPS
module is responsive.
On 2015-05-31 16:47, Bob Camp wrote:
> 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.
>> On May 31, 2015, at 11:58 AM, Vlad <time at patoka.org> wrote:
>> 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:
>> 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:
>> 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:
>> 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 !
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