WWVB demodulator

Has anyone on the list worked on a WWVB demodulator?

They basically use a type of ON/OFF keying, with the resulting “pulse
width” used to encode 1s and 0s.


Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

On 12/26/2010 09:54 PM, Michael O. wrote:

I started to years ago but never got very far. It looked like
starting with goertzel was going to work. I think I planned to dump
goertzel output into M&M clock recovery with a 10 Hz symbol rate and
then count the number of .1 second chunks per pulse.

mossmann

I’m not too worried about computational efficiency, so I hadn’t
considered Goertzel. My current approach
(that I’ve just developed this evening :slight_smile: ), is to assume a 192KHz
sound card input (which is congruent with
the approach I’m currently using for VLF signal processing for
ionospheric measurements), bandpass filter at
60KHz (+/- 100Hz), then detect the result and data slice into 1s and
0s at 10Hz–the data slicing is driven by
computing a longer-term signal level average (since WWVB basically
uses ON/OFF (well ON, and 10dB down)
keying.

Having a variable that tracks the medium-term average allows the
receiver to track fading and tweak the data slicer
appropriately.

Haven’t decided how I’ll turn the PWM into actual 1s and 0s yet.


Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium