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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