[time-nuts] GPDSO is working
Bob Camp
lists at rtty.us
Fri Jul 12 16:01:06 UTC 2013
Hi
You will need to fine tune the firmware settings for that OCXO.
Bob
On Jul 12, 2013, at 11:27 AM, Bob Stewart <bob at evoria.net> wrote:
> Hi Bob,
>
> OK, you got me: time as in about 120 minutes. =) It's mostly "+", with the occasional "-" for about an hour or so. Then, it wavers back and forth between "+" and "-", but the long term trend is still very slowly "+". So, I guess the OCXO needs more time to "settle in"? My OCXO is a Trimble 34310-T.
>
> As soon as I can get the serial port wiring done I'll be able to tell if it's in "position hold" mode. I suspect it's not, as it doesn't have a battery on-board. I did wind up mounting a Lithium 3V backup battery, using a holder from an old motherboard.
>
> I'll have to look around to see if anyone has any software to graph the DAC track for this board.
>
> Bob - AE6RV
>
>
>
>
>
>> ________________________________
>> From: Bob Camp <lists at rtty.us>
>> To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
>> Sent: Friday, July 12, 2013 8:47 AM
>> Subject: Re: [time-nuts] GPDSO is working
>>
>>
>> Hi
>>
>> On Jul 11, 2013, at 11:59 PM, Bob Stewart <bob at evoria.net> wrote:
>>
>>> After ham-fistedly breaking a few things, I've finally got my GPSDO working. (does happy dance) Now that it's had some time to warm up
>>
>> Time as in minutes, or as in a couple of days? If you look at the plot in the QEX article, a day or so is the expected "warmup" period.
>>
>>> I see that it's started wandering around +/- a couple of counts from sample to sample (16 seconds).
>>
>> If it's + *and* - then the gizmo is driving down the middle of the road. If it's always + or always - then it's likely not yet locked.
>>
>>> Is this because the UT+ is not set to timing mode?
>>
>> The UT needs to be in "position hold" mode with a proper (24 to 48 hour) survey on it's location for best performance. It should not be +/- 100 ns even without this.
>>
>> Is your VCXO a 10811? Does it have the same sensitivity as a 10811? If not, you may need (per the article) to make some firmware changes.
>>
>> Bob
>>
>>> Putting in an RS-232 (or USB) to TTL adapter, switchable between the UT+ and the VE2ZAZ board, is pretty much next on my schedule. I've got an adapter I made many years ago, but it's not suitable for mounting in the box, and there's no simple way to hook it up to the UT+ at the moment.
>>>
>>> Bob
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