[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
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
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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.
> 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,
>> Dale NV8U
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