[time-nuts] WWVB PM Time Questions

[rcbuck at atcelectronics.com]

Paul and Rodger,

I used the actual transformer, YCL 20F001NG, and 1N4148 diodes like the
schematic shows. I isolated the grounds on the mixer because Rodger had
a note in the document saying he was picking up noise.

I experimented with the 60 kHz drive level and increased it to 285 mV
Pk-Pk, which is about -7 dBm. I also put a 50 ohm load between pins 1
and 3. I now see the sine wave on pin 1. But should it require that
amount of drive into the RF port?

What level of signal do you have coming out of your preamp circuits to
the mixer? If you have -7dBm that means your preamp has about 60 dB of
gain assuming a WWVB signal of 100 uV. I used 620 ohm resistors to drive
the MC34151 pins 10 and 15 which should be plenty of drive.

If I do a 5 second capture of the output from pin 1, I see the phase
reversals. The reversals are not always on the zero crossing point of
the wave. That is probably because of no phase coherence between the
input signal and the phase flips as Rodger said.

The signal is also no longer a sine wave but I believe that is due to
the limited memory in my scope. It is an old Tektronix TDS 2014B. I
really need to buy something more modern. This project may be an excuse
to do so.

Paul, what program did you use for the new attached schematic? It has a
.sch extension. I don't know what board program you used. Is it possible
to print the schematic to a PDF and attach it to your next message?

Ray


-------- Original Message --------
Subject: Re: [time-nuts] WWVB PM Time Questions
From: paul swed <paulswedb at gmail.com>
Date: Wed, August 19, 2020 7:08 am
To: Discussion of precise time and frequency measurement
<time-nuts at lists.febo.com>

Hi Ray yes actually a sine wave out. So something is wrong. Are you
actually using a mixer or the transformers and diodes I suggested?
Including a schematic that I believe is easier to read than the original
from 2015.
Note that the diodes are floating and that each side actually goes to an
active driver. There is always current going through the diodes. Either
forward or reverse.
Other possibility your over driving the flipper. I just built one up to
actually create the BPSK signal. Found that it needed to stay below
-8dbm
otherwise it would distort. But increasing the current allowed me to go
to
-3dbm.
Regards
Paul


On Wed, Aug 19, 2020 at 3:49 AM <rcbuck at atcelectronics.com> wrote:

> Paul,
>
> Yes, I built the d-psk-r per the schematic. However, I think I did not
> understand how it actually worked. I was expecting it to be able to
> duplicate the WWVB sine wave signal with the phase reversal present when
> the PM data bit changed from a 0 to 1 or 1 to 0. I have a 60 kHz sine
> wave going into pin 8 of the mixer transformer. I expected to see a sine
> wave out of pin 1.
>
> However, I looked at the code again and it appears the "LO" port of the
> mixer is only driven one per second. There is no steady drive to the
> "LO" port so there cannot be a sine wave out of the "IF" port. Is that
> correct?
>
> Or should there actually be a 60 kHz sine wave coming out of pin 1 on
> the mixer? If so, something is wrong with my d-psk-r. I am not trying to
> use it with any kind of receiver. I just want to see the sine wave on my
> scope.
>
> Ray,
> AB7HE
>
> -------- Original Message --------
> Subject: Re: [time-nuts] WWVB PM Time Questions
> From: paul swed <paulswedb at gmail.com>
> Date: Tue, August 18, 2020 12:19 pm
> To: Discussion of precise time and frequency measurement
> <time-nuts at lists.febo.com>
>
> Ray I would tend to agree but I actually am unclear on the context.
> Did you actually build a d-psk-r?
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
_______________________________________________
time-nuts mailing list -- time-nuts at lists.febo.com
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.