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

Dale J. Robertson dale at nap-us.com
Sun Oct 21 21:14:26 EDT 2012


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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