[time-nuts] New WWVB format...

[Majdi S. Abbas]

On Wed, Sep 26, 2012 at 10:13:22AM -0700, Tom Van Baak wrote:
> My reading of the document(s) is that the new format will in fact allow 
> WWVB to be used as a frequency standard with even greater precision then 
> before, though not with unmodified legacy WWVB carrier receivers. My hope 
> is that one of you will produce a clever reference design for such a T&F 
> receiver make it available to the group. It sounds like a very fun DSP 
> project; one that we can all learn from. Bonus points for making it an 
> open-source Arduino shield. Making it work with both DCF77 and WWVB would 
> also be a plus.

	DSP would be good, although I also think an microcontroller
implementation could be interesting.  Atmel's ARM MCUs look like they'd
be good candidates for this sort of thing.  (Pretty fast, enough storage
to do interesting things with it, and a fast enough ADC for 60 KHz.)

	I've got a couple of these that I might use as a development 
platform:

	https://www.olimex.com/Products/ARM/Atmel/SAM7-P256/

	Has anyone come up with a reasonable algorithm to implement in
a microcontroller?  (DSP development kits are a bit more spendy than I'd
like to invest in a prototype. :)

> If nothing else, a well-documented hack for existing Spectracom and HP 
> WWVB receivers would be welcome. A third idea is a translator that 
> receives the new carrier format and re-transmits the old carrier format; 
> that way no mods need to be made to legacy WWVB receivers at all, 
> regardless of age. It would be similar to the way the G2G (GPS to GOES) 
> translator worked. Extra credit for adding back the 45 degree hourly 
> phase shift.

	I'm not sure I want the phase shift back.  Some references
don't handle it gracefully.

	That said, I have the following victims (time interval and TOD):
		- TrueTime 60DC and 60LF
		- Spectracom Netclock/2 

	As far as I'm concerned I'm willing to modify any of these at 
this point.  I've got a rough idea how to modify the 60DC: seems like
you could double the 60 KHz LO after the IRIG output divisor chain, as
it's headed into the PLL, and double the incoming signal after the RF
amp.  This is convenient since it's running between assemblies, anyway.

	Does anyone have a manual or schematic for the 60LF?  I could
probably figure it out, but it'll be easier with documentation.

	Thoughts on modifications are welcome, I'd even be happy to compile
them all into a public list somewhere.

	--msa