[time-nuts] Frequency Dividers

Randy Warner Randy at synergy-gps.com
Tue Aug 8 20:19:55 EDT 2006


Said,

I understand that the micros work fine, it just seemed like you would
need a second one to discipline the OCXO because of the timing
constraints on the divider.

This brings to mind the original "roll your own" Motorola GPS chipset
that was released and killed quickly about 5-6 years ago. The concept
was great. I was REALLY amazed that Motorola GPS convinced their ranks
of lawyers to release the API......

The little "minor" problem was that the chipset ran a variation of the
standard "Oncore" code that has been the basis for all Motorola
receivers since the mid-nineties. This code requires servicing of a 1
KHz interrupt from the correlators in order to run. You can imagine how
much fun people had trying to write user programs with that interrupt
hitting them in the head 1000 times a second. I THINK green River was
going to come up with some sort of RTOS to make life easier, but by that
time there were cheaper, smaller alternatives.

Randy

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-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of SAIDJACK at aol.com
Sent: Tuesday, August 08, 2006 5:03 PM
To: time-nuts at febo.com
Subject: Re: [time-nuts] Frequency Dividers

 
In a message dated 8/8/2006 14:29:38 Pacific Daylight Time,
Randy at synergy-gps.com writes:
 
Hi Randy,
 
the Micro's allow you to do other stuff, like discipline the OCXO as
well  :)
 
BTW: I took a closer look at the Sparkfun board, the chip has a bunch
more Match outputs than I thought.
 
The Philips parts have great counters/PWM units (driven by an internal
PLL) for experiments.. The MSP430 should do the trick as well.
 
bye,
Said

Said,

Thanks for the clue on the Philips part. Sounds like a  nice solution.

I just got a couple of sample parts from Maxim that I am  going to play
with (DS4000, MAX5121, and MAX6629). If they can do what  Maxim claims
it might be a fun experiment. I have one of those little TI  MSP430 dev
kits that I am going to try to use to run the show. We'll  see.

Randy





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