For those of you who don't dare click on encrypted Yahoo URL's, the original NIST link is:

http://www.nist.gov/pml/div688/grp40/upload/NIST-Enhanced-WWVB-Broadcast-Format-sept-2012-Radio-Station-staff.pdf

Burt,

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.

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.

/tvb

----- Original Message -----
From: "Burt I. Weiner" biwa@att.net
To: time-nuts@febo.com
Sent: Wednesday, September 26, 2012 8:49 AM
Subject: [time-nuts] New WWVB format...

I may have at least the spectracoms figured out. Its a hack and at least
using my homebrew wwvb psk encoder seems to work. But its not a general
purpose design. It will work with the fluke 207 and HP 117s but you have to
have a base spectracom to hack.
Technically speaking unattractive.
But that said I am waiting for the real wwvb to send bpsk again to claim
any victory. Its a real challenge on the east coast as compared to folks in
the mid and central west areas that have produced answers...
I will also say that over the last 6 months. John and I have hacked a lot
of the "solutions". They do not fare well.
Regards
Paul
WB8TSL/1

On Wed, Sep 26, 2012 at 1:13 PM, Tom Van Baak tvb@leapsecond.com wrote:

Paul, I have a couple of Spectracoms running and have pretty decent WWVB
signal strength here.  I'd be happy to test the hack.

John

On 9/26/2012 1:32 PM, paul swed wrote:

On Wed, Sep 26, 2012 at 10:13:22AM -0700, Tom Van Baak wrote:

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. :)

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

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.

The wrong way to do it is to select hardware before you even have the
basic sketch of the software algorithm. The best way is "software
first".  You don't even need an RF front and.  You can simulate what
the D/A converter would see based on the transmitter spec and feed
that to your software before you even put up an antenna.  I worked on
a project where we actually did that.  We built a simulation of the
transmitter first.  At first the sim was very crude and simple.
Later we added noise, multi path  and so on.  This allowed the radar
receivers to be tested without special hardware and most importantly
it allowed regression testing of the software after every upgrade.

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.

Chris Albertson
Redondo Beach, California

On Wed, Sep 26, 2012 at 11:38:10AM -0700, Chris Albertson wrote:

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.

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

This is a job for Raspberry Pi...
Don

Majdi S. Abbas

--
"Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind."
De Erroribus Medicorum, R. Bacon, 13th century.
"If you don't know what it is, don't poke it."
Ghost in the Shell

Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
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