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

Dale J. Robertson dale at nap-us.com
Sun Oct 21 22:55:49 EDT 2012


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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