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
troubleshooting.
I soldered TTL Serail sniffer to GPS-FC and I got following:
(Rx)@@At 00
(Rx)@@At 00
(Rx)@@Aw 00
(Rx)@@Ea
060107DF0024190008E0BA0000000000000000000000000000000000000000000001000009000000190000001B000000130000001600000014000000020000000500000008
(Rx)@@En
0101000A010000010000000000000001010202000021092FAF080019800000001B00000000130000000D16FFFFFFFF1400000039020000006F0500000000
(Rx)@@Ea
060107DF00241A0009BC930000000000000000000000000000000000000000000001000009000000190000001B000000130000001600000014000000020000000500000008
(Rx)@@En
0101000A010000010000000000000001010202000020112FAF08001F8000000007000000000C0000FACD0FFFFFFFFF1800381998060022189B0400000000
(Rx)@@Ea
060107DF001F2F0002C27800000000000000000000000000000000000000000000010001110000001F000000070000000C0825A20F00000018000020060000200400000008
(Rx)@@En
0101000A0100000100000000000000010102020000FD112FAF08001F8000000007000000000C0001E5820FFFFFFFFF1800381998060022189B0400000000
(Rx)@@Ea
060107DF001F300003AD2C00000000000000000000000000000000000000000000010001110000001F000000070000000C0826A20F00000018000020060000200400000008
Which, I think, looks like Motorola protocol. And that means the GPS
module is responsive.
Regards,
Vlad
On 2015-05-31 16:47, Bob Camp 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 <t...@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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