[time-nuts] WWVB PM Time Questions

[Bob kb8tq]

Hi



> On Jul 22, 2020, at 3:51 PM, paul swed <paulswedb at gmail.com> wrote:
> 
> Ray watch out for my comment on the KD2BD solution. That oscillator isn't
> available and I have not been able to map something else into it. Tried
> several good grade Oven oscillators. Just be aware of that issue.
> Would need to do more tinkering and simply don't have that time right now.
> Also it would be great if the oscillator was something that could be
> obtained at a reasonable cost. I do not believe at all it has to be a
> OCXO as the older true time and spectracoms were not and they locked solid.
> So its a case of getting the control voltages right.

You can buy a surprisingly good little OCXO (for the price) on eBay these 
days in the  $3 to $6 range. Find one at 12.6 MHz and it will divide nicely to 
60 KHz. 19.2 MHz looks like a better candidate … Either way I have not (yet)
seen a 60 KHz multiple show up in the cheap category.

Bob


> Regards
> Paul.
> 
> On Wed, Jul 22, 2020 at 3:29 PM <rcbuck at atcelectronics.com> wrote:
> 
>> Thanks to all for the suggestions. I dug a ferrite rod AM radio antenna
>> out of the box this morning. I have a box of 10 left over from the late
>> 80s. It measures 0.950 mH so I will add some turns to get it to 1.5 mH
>> which will be easier to resonate at 60 kHz. Then I need to build up the
>> RF amp and run the output through a 60 kHz crystal filter. I have to
>> order the crystals since I don't have any on hand. It will take a couple
>> of weeks to get the front end working.
>> 
>> I am in Phoenix so the WWVB signal is of decent quality here even during
>> the daytime. My 25 year old cheap Casio watch will sync up within 2-3
>> minutes any time of day or night. It normally syncs at 2 am but I have
>> done tests to confirm daytime sync works reliably.
>> 
>> Mark, I know virtually nothing about SDR other than it works. I bought a
>> RTL-SDR.Com module a couple of years ago and played with it a little
>> bit. But it quit working and I haven't thought about SDR since then. My
>> Icom 7300 is a SDR and it works very well. I think to attempt to design
>> a SDR would be well over my head. I anticipate this project taking 2-3
>> months. If I get it working I will be glad to share everything with the
>> group.
>> 
>> Lester and Paul, I will test with the Costas loop as it may be the
>> easiest way to go. To test the Costas loop I am basically going to
>> duplicate the KD2BD design. I was reluctant about it in the beginning
>> but more reading seems to indicate it will be fine. My AWG allows me to
>> set the phase from 0 to 360 degrees independently on each channel so I
>> can use that for initial testing. That testing can be done prior to
>> getting the front end working.
>> 
>> Richard, is your software posted somewhere? I assume it allows you to
>> specify the time and date you want it to send. That would come in handy
>> for writing the code to extract the timer/date data. I have seen
>> examples of the Arduino transmitting the old AM signal but don't recall
>> seeing one that sends the BPSK stream.
>> 
>> I have a GPS time receiver with a 1.2 inch LED display that I built a
>> couple of years ago. I have it setup so the UART outputs the gprmc NEMA
>> string in case I want to look at it. I have a couple of spare GPS
>> modules lying around and several Arduino Uno modules. I have no problem
>> picking up the GPS satellites using only the patch antenna that is built
>> into the modules.
>> 
>> Ray,
>> AB7HE
>> 
>> 
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