[time-nuts] WWVB Dephaser Question

Fri Oct 9 19:23:31 UTC 2020

Hi

Since you need a MCU to decode the data, you might as well get
things in there sooner rather than later. There are a number of MCU’s
out there that have fast enough ADC’s to do the job. They do have limited
dynamic range. You can go to one of the 24 bit converters and have 
a ton of dynamic range. It’s all up to you.

Once it’s into the MCU, it’s just code :). Depending on how much cpu 
horsepower you have (and how much code you want to write) you can
go more or less crazy …. PHK has some interesting tidbits on his web 
site. http://phk.freebsd.dk/AducLoran/AducLoran-0.0.pdf <http://phk.freebsd.dk/AducLoran/AducLoran-0.0.pdf>

Bob

> On Oct 9, 2020, at 1:38 PM, rcbuck at atcelectronics.com wrote:
> 
> Paul, Bob,
> 
> I am not using any commercial receiver. I am building everything from
> scratch. The RF front end starts with a ferrite rod antenna feeding a
> differential first op amp followed by 5 stages of op amp filtering and
> amplification. When the last stage is fed to my spectrum analyzer
> (through attenuators) the WWVB signal is clearly visible. I'm now trying
> to figure out how to detect the phase shift so I can get the time data
> for my CPU to process and send to a display.
> 
> I already have a GPS based clock that I built so I thought the WWVB
> phase clock would be an interesting project.
> 
> Ray
> 
> -------- Original Message --------
> Subject: Re: [time-nuts] WWVB Dephaser Question
> From: Bob kb8tq <kb8tq at n1k.org>
> Date: Fri, October 09, 2020 7:35 am
> To: Discussion of precise time and frequency measurement
> <time-nuts at lists.febo.com>
> 
> Hi
> 
> At least to me, anything dimensioned in the 100’s of feet is
> “massive” compared to
> the rod antennas normally seen in WWVB use ….
> 
> The other point being that if the antenna is some sort of large loop,
> it’s going to be
> a good long ways away from the receiver. You get both a larger signal
> voltage and better
> isolation …..
> 
> Bob
> 
>> On Oct 8, 2020, at 11:30 PM, John C. Westmoreland, P.E. <john at westmorelandengineering.com> wrote:
>> 
>> Hello All,
>> 
>> Are there any design details someplace regarding these massive antennas?
>> 
>> Thanks,
>> John
>> AJ6BC
>> 
>> 
>> On Thu, Oct 8, 2020, 19:27 paul swed <paulswedb at gmail.com> wrote:
>> 
>>> Hello to the group.
>>> Ray as Bob mentions you are taking a 10s of uv signal to a logic level of
>>> maybe 4V.
>>> If the loop is any place close to the divided down signal, it will
>>> oscillate. It would take incredible shielding to protect the receiver.
>>> Thats why you often see a solution that doubles to 120 KHz and modifies the
>>> detectors to work at that frequency. That means hacking the radio
>>> internally. Not fun. The other really annoy effect is that the doubling
>>> slips phace due to noise and propagation. So if charting suddenly you get a
>>> 180 degree flip. Thats messy.
>>> The doubling solution can work. Search for carter and there are several
>>> others.
>>> But having tested and used all of the alternates and lots more on the east
>>> coast decided they were too much trouble. You should see the box of boards
>>> I have chuckle.
>>> For me I am very happy with the d-psk-r. Though in being above board I
>>> designed version 1 and Rodger and I did version 2. Its solid and no mods to
>>> any receiver. Everything has always been released to the time-nuts group.
>>> As they say have fun.
>>> Regards
>>> Paul.
>>> WB8TSL
>>> 
>>> On Thu, Oct 8, 2020 at 5:39 PM <rcbuck at atcelectronics.com> wrote:
>>> 
>>>> Bob,
>>>> 
>>>> I am using a ferrite rod antenna for the receiver. No outside antenna.
>>>> 
>>>> Ray
>>>> 
>>>> -------- Original Message --------
>>>> Subject: Re: [time-nuts] WWVB Dephaser Question
>>>> From: Bob kb8tq <kb8tq at n1k.org>
>>>> Date: Thu, October 08, 2020 12:40 pm
>>>> To: Discussion of precise time and frequency measurement
>>>> <time-nuts at lists.febo.com>
>>>> 
>>>> Hi
>>>> 
>>>> A lot depends on your antenna setup. You can also swamp out the incoming
>>>> WWVB signal…….
>>>> 
>>>> Bob
>>>> 
>>>>> On Oct 8, 2020, at 2:07 PM, <rcbuck at atcelectronics.com> <
>>>> rcbuck at atcelectronics.com> wrote:
>>>>> 
>>>>> I have read several different articles where the WWVB phase shift is
>>>>> eliminated by doubling the signal to 120 kHz. Several members of the
>>>>> list have built these units.
>>>>> 
>>>>> Assume I build a circuit to double the incoming signal and use a
>>> schmitt
>>>>> trigger to get a 120 kHz square wave. If I then divide that signal back
>>>>> down to 60 kHz will that signal be strong enough to swamp out the WWVB
>>>>> signal? I'm guessing it will be since it is at the 5 volt level and
>>>>> somewhere in the +25 dBm or greater range.
>>>>> 
>>>>> Ray,
>>>>> AB7HE
>>>>> 
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>>>> 
>>>> 
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