[time-nuts] Lucent RFTG-u REF0-REF1 cable
jerry at hanler.com
Tue Nov 14 12:55:11 EST 2017
Thomas, Yes, thank you, I read the work Dan posted.
I have this TAPR GPS with the M12+ board in it that I received for free after machining the end plates and the unused standby REF0 or REF1, can’t remember which has the GPS in it. I would like to have another 10Mhz standard in my office. I also have an OCXO out of my Tektronix 11301 I was given but that uses a trimmer that I can’t really mod to discipline so that option of GPS + OCXO is out. So I wouldn’t mind figuring out a way to take the TAPR GPS and feed it into the spare REF unit not unlike what the other REF unit is doing. I would then have to fake some data per Dan’s site. Having written this, I just might do this project now that I think about it. I could then also use an STM32F7 board with display to post a clock as well. I guess I would also have to tap off the (debatably dirty) 10Mhz signal internally in the one that is missing.
I’m going to go back and reread Dan’s paper. There were questions about the sawtooth IIRC and I remember seeing it when I compared the output of the TAPR 1PPS vs the Lucent 1PPS as they would jump phase by successive increments and then bounce back. I don’t think we ever determined which one was moving but I remember someone telling me it was most likely related to a sawtooth in the discipline. I don’t know enough about these things to say for sure, but watching the 1PPS vs the other made me start to wonder about the absolute phase accuracy of those signals. You would have thought they would have been perfectly in phase, no? I go to bed at night with the confidence that the free TAPR GPS is the culprit vs my Lucent that which cost me $200 when all done.
So in summary, I have to plug the GPS REF unit, tap-off the 10Mhz someplace on one or the other, feed the second REF unit with my TPAR GPS then also send it some text (which is known by Dan) and I should get a second disciplined 10Mhz unit. This will take me a few weeks during which I will get bored and forget why I was doing it in the first place. So please remind me when I post back.
> On Nov 14, 2017, at 8:50 AM, Thomas Petig <thomas at petig.eu> wrote:
> Hi Jerry,
> the 15 MHz is disabled by default, just bridging some pins enables the
> If you want to insert some 1PPS signal to discipline it, you need some
> fake some GPS messages. Dan has done some nice work here, a small ATTiny
> is sufficient.
> /Thomas, SA6CID
> On Tue, Nov 14, 2017 at 08:30:54AM -0800, Jerry Hancock wrote:
>> Bob, I thought you had to send it code, etc? I have the two units
>> with cable, etc running upstairs. I want another one for in my office
>> but the same guy only sells the REF0 and REF1 units separately now
>> without the cable. I thought about splitting the two and using this
>> other GPS unit I have (it was one of the TAPR GPS Kits) to send the
>> other one the 1pps. You’re saying all you need is a plug? I would
>> need two functioning units.
>> Jerry Hancock
>> jerry at hanler.com
>> (415) 215-3779
>>> On Nov 14, 2017, at 8:13 AM, Bob Camp <kb8tq at n1k.org> wrote:
>>> If you are going to get out the soldering iron, why simply make up a plug
>>> to run the GPS unit stand alone? Keep the second unit powered down
>>> as a set of spare parts….. Yes, it does depend a bit on what you are doing
>>> with them ….
>>>> On Nov 13, 2017, at 11:50 PM, Jerry Hancock <jerry at hanler.com> wrote:
>>>> Anyone have a spare cable for the Lucent setup? I guess I can make one with some DB15 connectors but trying to skip the effort.
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