Electronics > RF, Microwave, Ham Radio

WWVB receiver advice

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ledtester:
I'd like to build a WWVB receiver. I've found two designs:

- one by Russel Kincaid published in Nuts and Volts, May 2006 (see attachment)
- another by Hans Summers - http://www.hanssummers.com/images/stories/radio/report.htm

I have a couple of "atomic" clocks, so I figure their loop stick-cap assemblies could be helpful in building my own receiver since they are most likely already tuned to 60 KHz.

My questions:

The Kincaid design calls for 3x 680uH inductors. Any good suggestions for how to go about making these? Since 680uH is a standard inductance, will something like this RF choke work (Mouser P/N 434-17-681J)? http://www.mouser.com/ProductDetail/Fastron/07P-681J-50/?qs=%2fha2pyFadugl%2fvul%2fEqHt6RvekLGgR1gz%2f98kulmaXo%3d

The Summers's design calls for two 3.5mH inductors which are described as:

"Coil L1 and L2 were wound from about 95 turns of swg 30 wire on Maplin Ferrite core type 2, LA4345."

However, I can't find any source for "Maplin Ferrite core type 2, LA4345". Any ideas of an alternative?

Thanks!



cdev:
Here is an antenna that likely works well. You could probably make it smaller if you used a larger capacitance.

http://www.febo.com/time-freq/wwvb/antenna/index.html

JimRemington:

--- Quote ---I have a couple of "atomic" clocks, so I figure their loop stick-cap assemblies could be helpful in building my own receiver since they are most likely already tuned to 60 KHz.
--- End quote ---
In many of the clocks, the receiver is an entire separate module, which works fine as it is. You probably can't do any better building one yourself, so take one apart and see how well it works (I have done so).

They are crystal controlled direct conversion receivers that typically run on 1.5 - 3 V and output a low voltage pulse that corresponds to the AM modulation of the WWVB carrier, to be decoded elsewhere. Ed Nisley posted Arduino code in the April 2010 issue of Circuit Cellar, which decodes the signal and does extensive error and sanity checking. The article was entitled something like "A Totally Featureless Clock".

cdev:
I've seen a few stories that might be relevant.  Sometimes people find hardware that contains WWVB receiving capabilities, very very cheaply, it doesnt always work though.

There is a WWVB refclock for NTP and so its possible that you could build a very cheap way of keeping a computer time server in sync that would be separate and distinct from GPS, which IMHO would be useful in terms of redundancy.

With the appropriate antenna, and software, you might be able to receive the 60 KHz WWVB signal perhaps using some PC sound cards - For low frequencies that might work quite well. You could perhaps interface it to NTP using the NTP WWVB refclock- Not important to most people but I know that with HF (3-30 MHz) tiny variations in signal propagation makes received frequencies including WWV jitter - but by very small amounts. I don't know how much lower frequency propagation jitters, it might not jitter as much.

MrSlack:
Used to be able to get antennas for this ready made in the UK that were good. Ferrite stick ones. Managed to build a simple receiver in the distant past for Rugby MSF but never got to  decoding the signal before I got bored. Was a simple TRF receiver.

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