[time-nuts] Re: Isotemp OCXO question

[Bob kb8tq]

Hi

The WWVB transmitters are military surplus. I suspect they got them at a very
low cost to NIST. The proposal they kept floating was to set up a second LF
time signal for the east coast. That way they could do better coverage over
the entire county without going to higher power. My guess is the same 
surplus transmitters would have been dropped into someplace in New York.
It would also let them go to a frequency that was not as heavily impacted by
MSF.

Nobody ever really got behind the idea. It came up again and again. It just
never got any traction. Finally they went with this phase mod stuff. 

Bob

> On Aug 21, 2021, at 1:45 PM, Robert DiRosario <ka3zyx at comcast.net> wrote:
> 
> This will just be a backup clock in my amateur radio station.  I already have a Truetime XL-DC and a XL-AK, both have GPS receivers that give IRIG-B and 1PPS outputs, and drive a couple of IRIG-B clocks.  I would guess the GPS time signal will be more accurate and precise then WWVB, and both will be more accurate and precise then my Heathkit Most Accurate Clock, which uses WWV.
> 
> To the human eye, as long as the seconds match on all sources, I'm happy.  On the other hand, for my GPS-NTP box and especially for my GPS-DO frequency standards, I want a lot better then 1 Hz.
> 
> I really wish NIST didn't add the BPSK modulation to WWVB. Increasing the transmitter power would have been a lot better, but I'm sure that would have cost a lot more then just changing the modulation.
> 
> Robert
> 
> 
> 
> On 08/19/2021 09:19 PM, Bob kb8tq wrote:
>> Hi
>> 
>> The issue you run into is that the fancy devices tried to derive information from
>> the phase of the WWVB signal. With an “AM only” receiver accuracy in the 10’s
>> (or 100’s … yikes ….) of ms was pretty common. With a phase oriented approach,
>> you could get into the 100’s of us. Indeed there is a lot of fine print involved with
>> any WWVB claims.
>> 
>> The change over did not impact the typical WWVB watch or an AM based receiver.
>> It very much messed up any of the fancy timing stuff.
>> 
>> Bob
>> 
>>> On Aug 19, 2021, at 9:09 PM, Robert DiRosario <ka3zyx at comcast.net> wrote:
>>> 
>>> I have a MAS6180C AM receiver chip, on a board with a few other parts to complete the receiver.  I did not make the board, it came from
>>> Universal-Solder Electronics in Canada.  The date on the chip datasheet is 2014 and on the receiver board 2016, so after NIST messed up WWVB in 2012.
>>> 
>>> Robert
>>> 
>>> 
>>> On 08/19/2021 07:23 PM, Bob kb8tq wrote:
>>>> Hi
>>>> 
>>>> It’s a good bet that whatever the spec on that Isotemp OCXO, it’s way better in terms
>>>> of temperature and aging then the DS3231. Is it still on frequency (however many years
>>>> later …..) who knows ….
>>>> 
>>>> Many of the “time oriented” WWVB devices stopped working when they put in the new
>>>> modulation scheme. It’s a pretty good bet that this applies to the device you have.
>>>> 
>>>> Bob
>>>> 
>>>>> On Aug 19, 2021, at 6:55 PM, Robert DiRosario <ka3zyx at comcast.net> wrote:
>>>>> 
>>>>> I got a  Trak Systems "Time Code Translator" from ebay.  It's a 1U box with large LEDs for DOY and H/M/S that translates IRIG-A to NASA-36 time code.  I plan on using the case for my WWVB clock.
>>>>> 
>>>>> Unexpectedly it has an Isotemp OCXO in it, model OCXO59-11-2, frequency marked as 1.000 MHz  The Isotemp website is more or less dead, it has no information on it.  Does anyone have any information on this model, like how accurate it is?  It has only three wires, which I assume are power, ground and output, with no EFC input.
>>>>> 
>>>>> One thing that I'm sill note sure about is what to do when the receiver is not receiving WWVB.  I was thinking of using something like the DS3231 RTC module.  If this OCXO is better, I may use it.
>>>>> 
>>>>> Thanks
>>>>> 
>>>>> Robert
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