[time-nuts] WWVB cheap chip saa6579 RDS decoder back to the chip

paul swed paulswedb at gmail.com
Sat Oct 27 12:18:45 EDT 2012


Hello to the group.
I see the thread took a left turn a day or so ago so thought I would fire
up a new one for the interested in the phillips saa6579 RDS chip.
Several others have purchased this chip. Jameco electronics had them for 10
or 20 cents. I picked up 10. You had order that many as I recall. Its a
costas loop but will say the documentations skimpy.

My interest
Restoring the old style frequency rcvrs to operation. Like the HP vlf117,
tracor 599, fluke 207....
A byproduct of accomplishing that is you can restore the old time rcvrs
also like the spectracom 8170s.
Lastly end up with the new wwvb code to do something with. Thats really low
on my list of interests actually.
Have tried many approaches to date. The doubling and dividing stuff.
Fades and noise are a killer for this approach. So stopped work on those.

One hack that works is a small fast uproc that detects phase flips using a
spectracom 8163 VCO chain as the reference.
When a flip occurs you flip an rf amplifier phase to invert it.
Its a hack and you need a spectracom. But this voids a favorite requirement
of mine KISS.
So currently building a discreet costas loop using ad633s see how that
works.

To the saa6579
As mentioned in the other thread.
Simple to hook up.
Cheap
Requires 1000uv or more so that ends up making things more complicated.
But in my case simply did not really work at 57 or 60 Khz.
As some someone pointed out you may have to take the clock and data to a
flip flop to get the correct information.
Regards
Paul
WB8TSL



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