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

[Bob kb8tq]

Hi

One as yet unasked question:

What sort of antenna are you using to feed WWVB into the device? 
Is it the one that Symmetricom used? In the past, I’ve had way more
trouble locating correct antennas than finding this or that WWVB 
based device ….. On some devices much of the receiver was in the
antenna. There are a number of older GPS based devices with the 
same sort of issues. 

Bob

> On Sep 3, 2022, at 5:23 AM, Todd Smith via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> 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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