[time-nuts] WWVB BPSK Receiver Project?

J. Forster jfor at quikus.com
Thu Mar 15 01:45:22 UTC 2012


In thinking about it a bit further, one might be able to take the 60 kHz
received sine at some point in the receiver, full wave rectify and HP
filter it (which doubles the frequency) then divide by two in a Flip-Flop
and heavily filter the resultant. This is a hybrid solution... analog and
digital...  with not a uP in sight!!

That would preserve the frequency, but ditch the phase reversals of the
BPSK. Depending on the guts of the particular receiver, it might be
possible to simply retrofit a PCB.

The 180 degree phase reversal of the BPSK is just about the worst possible
thing for a PLL of typical receicers. If the ratio of 1s to 0s is 50% the
loop just thrashes.

-John

================




> OK thats great a maybe pic chip answer. They do cure all ill's after all.
> Really scratching my head here. But I do think there is an answer as long
> as the phase reversal is accurately controlled and still referenced to the
> reference standard.
> A I say I need to read.
> Regards
> Paul
>
> On Wed, Mar 14, 2012 at 9:14 PM, WB6BNQ <wb6bnq at cox.net> wrote:
>
>> Brooke,
>>
>> In speaking with John Lowe of NIST (Group Leader for Time & Frequency
>> service), he stated that the absolute time recovery of
>> their intended new modulation scheme is 10 milliseconds.  Nothing
>> stellar
>> there !
>>
>> BUT you are right, all of us that have hp-117 type receivers are just
>> out
>> of luck.  John Lowe did say they are going to
>> produce a PIC (Microchip) project that will grab the data stream and
>> reconstruct the carrier signal so that can then be fed
>> back into a hp-117 type receiver so it can still be used.  However, he
>> did
>> say that is a dream at the moment as they have
>> not really started to work on it.  He then said I could do it and they
>> would consider my efforts.  While I had a number of
>> thoughts running though mind when he said that; I did hold my comments
>> back.
>>
>> I have to tell you, John Lowe sounded like he was drinking the Kool-Aid
>> because I told him I was quite negative to the whole
>> idea and he went into a nonstop mode of telling me all the good things
>> that were going to come about with this modulation
>> scheme.  The same kind of hype that occurred with the HDTV.  By the way,
>> all those good things have nothing to do with
>> anything Time-nutty except for pissing us off, as it were.
>>
>> His enthusiasm was aimed totally at new products.  Although he admitted
>> it
>> leaves all the real Timenut type people, actually
>> using the system for its intended purpose, out in the cold, he really
>> did
>> not seem to care.  Pointing out that a failure
>> with the GPS system left WWVB as the only alternate did not seem to
>> matter
>> either.
>>
>> OH Well,
>>
>> Bill....WB6BNQ
>>
>>
>> Brooke Clarke wrote:
>>
>> > Hi John:
>> >
>> > They are going to maintain the existing AM modulation format so all
>> the
>> WWVB "Atomic Clocks" will still work.  The phase
>> > modulation is added on top of that.
>> >
>> > Yes, I expect my HP 117 may no longer work, but I'd much rather have
>> the
>> improved s/n and timing accuracy.
>> >
>> > Have Fun,
>> >
>> > Brooke Clarke
>> > http://www.PRC68.com
>> > http://www.end2partygovernment.com/Brooke4Congress.html
>> >
>> > J. Forster wrote:
>> > > All very nice, but if this change renders all existing receivers
>> useless.
>> > > How does that improve things?
>> > >
>> > > All it does is wipe out all the existing phase tracking
>> infrastructure.
>> > >
>> > > The only benefit is to the government who can reuse the WWVB
>> transmitter
>> > > and frequency allocation. Everybody else will have to buy new stuff.
>> > >
>> > > Sounds a lot like HDTV fiasco. Making jobs (in China or Korea) by
>> making
>> > > scrap.
>> > >
>> > > YMMV,
>> > >
>> > > -John
>> > >
>> > > ==============
>> > >
>> > >
>> > >> Dear Time-Nuts,
>> > >>
>> > >>
>> > >>> I sure would like a WWVB BPSK receiver for the new modulation.
>> (..)
>> > >>>
>> > >>> I'm sure in time there will be plenty of low cost ICs designed to
>> > >>> receive the
>> > > [SNIP}
>> > >
>> > >
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>> >
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