[time-nuts] WWVB PM Time Questions

[Dana Whitlow]

That phase reversal when the waveform is not at a zero crossing probably
adds appreciably
more high frequency content than a phase reversal at a zero crossing.  In
ham parlance,
I'd say it would introduce pretty severe "key clicks".

Have you considered writing a program to generate the right waveform to
load into your
AWG?  Then you'd have complete control.

Dana


On Mon, Jul 27, 2020 at 6:08 PM <rcbuck at atcelectronics.com> wrote:

> I have been playing with the 74HCT4046 PLL over the last couple of days.
> I have the VCO running at 90 Hz and my AWG running at 90 Hz as the input
> source to lock the loop. The AWG is modulating the 90 Hz sine wave with
> a PSK signal at a 9 Hz rate.
>
> I slowed the signals down from 60 kHz to 90 Hz to better observe the
> phase reversal. I could see the reversal at 60 kHz but could not capture
> it for a single sequence photo. Attached is the jpg of what the signal
> looks like when it performs a 180 degree reversal. With my AWG the
> reversal always occurs at the top or the bottom of the sine wave instead
> of at the center like John Lowe shows in the WWVB document.
>
> I ordered parts from Mouser this morning to build the RF front end.
> Hopefully I will be able to get a clean enough sine wave from WWVB to
> see what their phase reversal actually looks like. Then I will have to
> come of with the best/simplest way to detect the change. As was
> previously mentioned, the normal phase needs to be detected at the top
> of the minute. That means it will take at least 2 and probably 3 minutes
> to obtain a valid date/time data transmission.
>
> Ray,
> AB7HE
>
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