[time-nuts] Re: Syncserver S300 LFR 60 kHz WVVB

[rodger_adams at yahoo.com]

Hey Todd,

I think you are probably correct that your issue is caused by the BPSK
modulation.  There are at least 2 members of this list that have worked on
solutions to the BPSK removal problem.  Paul Swed created a nice solution
and he and I are currently running this "d-psk-r" circuit and are using the
"corrected" WWVB signal to drive various old WWVB devices, including HP-117
phase comparator, Fluke 207 comparator, various Spectracom comparators,
Spectracom Netclocks, R-1407/URQ comparator, and probably a few more.

The d-psk-r that we are running uses an Arduino to generate the 1pps bpsk
code and then a simple mixer (phase flipper) to process the received signal
directly at 60 khz.  Of course the Arduino circuit needs to be in sync with
the WWVB phase modulation so we use a GPS module to get the time and clock
the Arduino using the GPS's PPS output.  It might seem like cheating to use
GPS to correct the WWVB BPSK but if the goal is to return vintage hardware
to operation it's a pretty good way to go and works very well.  One d-psk-r
can drive all the 60 khz devices you want.   If you want to eliminate the
GPS cheat, there are other ways to go.  I've created a module that can drive
the d-psk-r Arduino using a WWVB clock module emulating GPS NMEA sentences
and PPS pulses.  There are also some other circuits floating around
including a Costas loop demodulator but I didn't have much luck with that.
I'm not aware of any commercially available product to solve the problem.

If you search the group archives you'll find lots of discussions on the
topic.  If you're not afraid to play around with Arduinos and soldering
irons, you can build the d-psk-r easily for under $100.  We've written up
some pretty reasonable documentation which we're happy to share if you're
interested.

I know that Paul and I are still currently using (and to some extent
improving) his d-psk-r.  I'd be very interested to learn if there are other
list members using any other solution(s) or if anyone even thinks it's still
a topic worth pursuing.

Good luck,

Rodger

-----Original Message-----
From: Todd Smith via time-nuts <time-nuts at lists.febo.com> 
Sent: Friday, September 2, 2022 11:49 AM
To: time-nuts at lists.febo.com
Cc: Todd Smith <tssmith2002 at gmail.com>
Subject: [time-nuts] Syncserver S300 LFR 60 kHz WVVB

Hello



I stumbled upon this list while looking for some information to refurb a
couple of older Symmetricom (Microsemi) S300 Syncserver NTP appliances
equipped with the optional LFR 60 kHz kit.  I believe that I am receiving
signal at my location since the LED on the back of the unit beside the LFR
antenna  port blinks while it is running.  It shows unlocked in the GUI
since it is apparently not decoding the signal.



I have read where in 2012, NIST changed the format for WVVB from AM to a
phase modulation and some receivers might not be able to decode the phase
modulation.  Do you think that is the case here?  I need to get another WVVB
receiver and test that I can receive signal at this location but I am high
enough and away from interference sources so that leads me to believe that I
am probably receiving signal.  Over 72 hours on the graph in the GUI and it
never decodes a signal yet the back blinks the entire time.



If phase modulation is the issue; is there a demodulator that I can get to
correct the signal format?



Thank you for your time

Todd Smith
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