[time-nuts] WWVB Dephaser Question

[rcbuck at atcelectronics.com]

Paul and Bob,

Thanks for the comments. I figured I wouldn't be able to get a 60 kHz
signal anywhere near a WWVB receiver. I just wondered how bad the signal
leakage from the divider IC would actually be. It is at a 5V logic level
but I don't know if that means 5V of signal radiation.  
 
I was trying to come up with a simple way (2 or 3 IC solution) to detect
the phase changes to decode the time data. I'm not interested in using
the signal for frequency measuring purposes. Doubling to 120 kHz doesn't
work for detecting the phase change because the change disappears.

I've looked at the block diagram of the ES100 module for hints. They are
doing something that doesn't require a lot of  processing power as they
are running the processor at 16 MHz. I guess the processor could have a
PLL in it to increase the CPU clock speed. Somehow they are using that
16 MHz as part of the demodulation scheme. They show the ADC and
oscillator feeding into a demodulator block. But 60 kHz isn't an integer
divider into 16,000,000.

Paul, so far I only have 5 or 6 boards but I'm sure I will have more as
I continue testing. I'm in Phoenix so the WWVB signal is fairly strong
here. The WWVB coverage maps show the signal as being 1mV during the
day. I know my wrist watch will synchronize during the day when I
replace the batteries.

Ray 

-------- Original Message --------
Subject: Re: [time-nuts] WWVB Dephaser Question
From: paul swed <paulswedb at gmail.com>
Date: Thu, October 08, 2020 3:43 pm
To: Discussion of precise time and frequency measurement
<time-nuts at lists.febo.com>

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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