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

[Todd Smith]

I am away from the unit for the holiday but the only picture that I have at
the moment is this one which shows the Multi tech modem attached to it.
The board contains the LFR and a spot for an optional modem.  It is
connected to the main system board by a multipin ribbon cable.  Given that
the system board contains a Intel Atom N2700, this connection might be
RS232.

I will try to get a better picture on Tuesday but there is very little
circuitry on this daughter card except for the modem.  I guess there
doesn't take much to decode WVVB.  I think I remember just 1 IC and several
resistors.

Todd

On Fri, Sep 2, 2022, 18:02 Graham / KE9H <ke9h.graham at gmail.com> wrote:

> Todd:
>
> What does the interface between the WWVB receiver and the rest of the unit
> look like?
> What timing accuracy did they spec when running off the WWVB receiver
> (back when it worked?
>
> --- Graham
>
> On Fri, Sep 2, 2022 at 2:40 PM Todd Smith via time-nuts <
> time-nuts at lists.febo.com> wrote:
>
>> I inherited these two units at work and they haven't been looked at for a
>> long time since they just work.  I ordered two replacement M12M receivers
>> from Jackson Labs to deal with the GPS rollover coming up in Sept for
>> these
>> units.
>>
>> I was looking at the modem logs and it looks like the USNO modem line in
>> DC
>> is down.  It rings but doesn't pick up.  I didn't see a way to report that
>> from the website.  I updated the numbers to NIST and to the working USNO
>> number in CO.
>>
>> The LFR and GPS antenna are already run and are working.  I know that I
>> can
>> use GPS but I wanted to have all timing options running for backups or to
>> protect from GPS failure or spoofing.
>>
>> I would very much like to see what options are available to either modify
>> the existing LFR board or put something in front of it that can send it
>> the
>> correct 60kHz signal.
>>
>> I know that it is not necessary but I like things working on my watch.
>>
>> Thanks for your help.
>> Todd
>>
>> On Fri, Sep 2, 2022, 14:20 <rodger_adams at yahoo.com> wrote:
>>
>> > 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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>> an
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>> >
>> >
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>
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