[time-nuts] WWVB New Modulation five cent demodulator / carrier regenerator ?
brooke at pacific.net
Sun Oct 21 22:37:06 EDT 2012
Is it as simple as changing the clock to operate at 60 kHz?
Dale J. Robertson 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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