[time-nuts] WWVB New Modulation five cent demodulator / carrier regenerator ?
Dale J. Robertson
dale at nap-us.com
Tue Oct 23 07:34:07 EDT 2012
According to the Phillips original data sheets quick reference chart the
chip wants to see around 1mV of input signal.
The output will not be a digital data stream with ones and zeros
corresponding to the phase of the input.
Instead, from what I can glean from the datasheet, it will be a pulse of
period 60KHz/48 every time the phase flips. Additionally there are outputs
of the costas loop recovered carrier, recovered carrier divided by 48 and a
quality indicator which I believe indicates that the loop is 'locked up'
I believe that to recover the data stream (assuming there's a good signal
etc.) you just need to feed the output into a toggle flip flop. The polarity
of the data at this point would be ambiguous and some other aspect of the
encoding (framing sync, checksum etc.) would have to be used to establish
proper data polarity.
It seems there are several possible uses of this chip. It might make a good
start on the 'brains' of an automatic phase flipper to be inserted into boat
anchor WWVB based frequency standards. The 60KHz output could form the basis
for an 'on the cheap' scratch built frequency standard.
I hope to get my chips pretty soon so I can see if any of this is really
From: paul swed
Sent: Monday, October 22, 2012 10:29 PM
To: Tom Miller ; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] WWVB New Modulation five cent demodulator / carrier
I was giving it 1000uv. Thats why I say it needs a lot.
On Mon, Oct 22, 2012 at 9:00 PM, Tom Miller <tmiller at skylinenet.net> wrote:
> ----- Original Message ----- From: "paul swed" <paulswedb at gmail.com>
> To: "Discussion of precise time and frequency measurement" <
> time-nuts at febo.com>
> Sent: Monday, October 22, 2012 8:35 PM
> Subject: Re: [time-nuts] WWVB New Modulation five cent demodulator /
> carrier regenerator ?
> To switch correctly at the zero point I sample the plus of the secondary
> with a LM339 comparator (only using 1 section) and feed that to a SXB
> running at 40 Mhz. Detect the zero and switch if I want. The micro
> in basic and screams along. So I can flip at any rate or create patterns
> easily as I can think them up. Its seriously dumb, simple, and stupid. But
> it lets me run tests without waiting for wwvb. I do attenuate the output
> signal to about 60 uv. Generally what I see on the east coast during the
> Hi Paul,
> Reading the spec, I think the chip wants to see about 500 UV RMS. Is that
> At three cents each, it sure would be nice to find another use for it.
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