[time-nuts] WWVB New Modulation five cent demodulator / carrier regenerator ?

Tom Miller tmiller at skylinenet.net
Thu Oct 25 03:05:52 UTC 2012


Hello Paul,

I guess you tested it at 57 kHz? Were you able to get it to work with your 
simulator at the normal frequency?

Does anyone have details on the test mode?


I just picked up $3 worth.


Regards,
Tom


----- Original Message ----- 
From: "paul swed" <paulswedb at gmail.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Sunday, October 21, 2012 11:08 PM
Subject: Re: [time-nuts] WWVB New Modulation five cent demodulator / carrier 
regenerator ?


Jameco had them on sale for 20 cents each so I purchased some.
Moved the clock up frequency for 60 Khz and injected the 60Khz BPSK. (I
built a simulator) It did not track and in general produced noise. I
understand you can use 2 frequencies to drive it and I tried both from
synth gens.
I was looking at the RDS decoders and the data seemed to be differential.
Set it aside at that point. I am curious as to why it did not work. Like
everyone here would be great if it worked....
Regards
Paul
WB8TSL

On Sun, Oct 21, 2012 at 10:55 PM, Dale J. Robertson <dale at nap-us.com> wrote:

> Paul,
> I'm trying to understand your reference to 'differential BPSK'  all the
> RDS references I've looked at indicate a 180 degree phase shift just like
> WWVB. I'm thinking that differential and antipodal are just different 
> words
> for the same thing
> Regards,
> Dale
>
> Sent from my iPhone
>
> On Oct 21, 2012, at 10:03 PM, paul swed <paulswedb at gmail.com> wrote:
>
> > Because it use differential BPSK. I have a number of them and was trying
> > it. There is a test pin that might make it useful.
> > Regards
> > Paul
> > WB8TSL
> >
> > On Sun, Oct 21, 2012 at 9:14 PM, Dale J. Robertson <dale at nap-us.com>
> wrote:
> >
> >> While looking for other stuff I came across the data sheet for the NXP
> >> Semi SAA6579.
> >> The chip is a purpose built demodulator for RDS (which utilises a 57 
> >> KHz
> >> ABPSK subcarrier on FM broadcast that is) used for traffic, song info
> etc.
> >> This chip has an anti-aliasing front end low pass filter and an 8th
> order
> >> bandpass filter followed by a costas loop and provides a phase
> synchronous
> >> regenerated carrier. What's interesting is that the switched cap
> bandpass
> >> filter and the synchronous detector are both driven by clocks derived
> from
> >> a local crystal oscillator which is spec'd at 4.332 or 8.664 MHz (76 or
> 152
> >> X carrier chosen by a mode select pin) I'm thinking it should be
> possible
> >> to use a 4.56 or 9.12 MHz crystal or external clock to use this chip
> as-is
> >> on 60 KHz.
> >> Have a look at the data sheet and tell me why I'm full of it.
> >> Jameco is closing out these chips in DIP-16 at a nickel apiece,
> >> $3.00/hundred.
> >>
> >> Dale NV8U
> >>
> >>
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