[HH] WWVB repeater or emulator

[Tom Metro]

Tom Metro wrote:
> I have several clocks in my house (and a watch) that all set their time
> using the 60 kHz radio broadcast time signal originating from Fort
> Collins, Colorado (callsign WWVB).

You can listen to what this signal sounds like here:
http://www.rescueelectronics.com/WWVB.html

or here:
http://www.youtube.com/watch?v=0m5AT67Apvs


You can find receivers for the signal here (though this one is no longer
sold by Sparkfun):
https://www.sparkfun.com/products/10060


> In any case, I've periodically searched online to see if anyone has
> built a circuit that either acts as a repeater for the WWVB signal, or
> emulates it, using a GPS receiver or Internet NTP server as a time
> source.

I've ran across this thread before:
http://www.radiobanter.com/showthread.php?t=62837

which suggests building a large coil as a passive field concentrator.
Others in the thread suggested creating an attic antenna, wiring it to a
preamp, and then inductively coupling the output to your clock (i.e.
running a few loops of wire around the clock's frame).

Neither approach sounds like it would be effective if you want to boost
the signal to multiple devices spread throughout a house.


This thread shows a design for a 60 KHz transmitter driven by a micro:
http://doityourselfchristmas.com/forums/showthread.php?11305-60-khz-Transmitter

This ntp mailing list posting:
http://lists.ntp.org/pipermail/questions/2011-June/029763.html

asking about an NTP->WWVB emulator points to a commercial product:
http://www.c-max-time.com/home/index.php

which costs $487, and is listed as discontinued by Digikey. The vendor
has other similar products, but no pricing or distributor information.
They look expensive. But at least this proves it is a viable idea.


> ...a graduate student project to build a repeater.

I think this is the paper (Google Quick View):

Self-Powered Repeater for Radio Controlled Clocks
https://docs.google.com/viewer?a=v&q=cache:TZugYGZ-V38J:courses.engr.illinois.edu/ece445/projects/fall2010/project3_design_review.pdf+wwvb+repeater&hl=en&gl=us&pid=bl&srcid=ADGEEShH7T398ioCC9AvCDZcsg19K5GXGLi_UWxEfrXpChTdFFV-cJY93myUKG1yON1b4P-F70HpsYJc1dFRKDQXT5CbOV2uiDZ4E3y4SMFiWTtEcf0IyLDzJh5We0jtwTkG9NgOajHR&sig=AHIEtbQmMoopHpA-4JDXb4GO26QJcceKbQ

(Original PDF):
http://courses.engr.illinois.edu/ece445/projects/fall2010/project3_design_review.pdf

The paper doesn't address how they planned to handle feedback, nor does
it include complete schematics. It would take some legwork to track down
the student to see if they actually built it.

 -Tom