[time-nuts] New WWVB format...

Majdi S. Abbas msa at latt.net
Wed Sep 26 18:59:33 UTC 2012


On Wed, Sep 26, 2012 at 11:38:10AM -0700, Chris Albertson wrote:
> The first stepis to simply use a regular PC, maybe running Linux.
> This is the easiest and fastest platform to develop on.  It gets
> harder and takes longer if you use a smaller and more esoteric
> platform like a DSP or FPGA.  Using a quad core Intel chip is gross
> over kill but it allows for quick development.  Later with working
> software you have actually measurements in hand and can pick a "right
> size" processor.

	Normally I'd agree with you but where 60 KHz signals are 
concerned, I think I'd rather not use a PC.  There's just too much RFI.
A microcontroller with a single clock at a much higher frequency is less
likely to interfere with itself.  I'm not worried about exactly sizing
this, anything we're likely to use is more than fast enough to handle
this coding at such a low frequency.

> If you need a stating point a time code generator that outputs the
> "old" WWVB signal is available as part if the NTP source code
> distribution in a /test directory.  Is was written to help test NTP's
> time code reference clock.  NTP has a way to connect a time code that
> is at baseband to audio "sound card" and use it as a reference.  The
> test software produced the "old format" baseband.    I'm saying this
> so that no one wastes time reinventing wheels.

	I'm aware of the 'tg' program in the util directory, but that is
for WWV or IRIG audio.  To my knowledge, there are no extant simulators
out there for WWVB.

	Do you know otherwise?

	--msa




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