[ntp:questions] Re: WWVB 60kHz Receiver

David L. Mills mills at udel.edu
Tue Apr 25 03:08:20 UTC 2006


Understand the situation here has deteriorated to the point that I can't 
hear the signal at all with a good antenna and communications receiver. 
The signal is thorougly covered in wideband hash from the power line. A 
wee OEM board and loopstick simply won't cut it with any algorithm. The 
only way to do that may be to synchronoualy demodulate the I and Q 
components and use a state machine and maximum likelihood decoder 
similar to the algorithm used in the WWV driver.


Jonathan Buzzard wrote:

> On Fri, 21 Apr 2006 21:11:07 +0000, David L. Mills wrote:
>>I've been down the fancy decoding path myself, e.g., the WWV driver, 
>>which is a theoretically optimum linear receiver. However, much of the 
>>crud found at WWVB and DCF77 frequencies is bursty, which is what my 
>>LORAN-C receiver and program is good for. The Spectracom receiver is 
>>actually quite good: however, it was designed to cope with Gaussian 
>>noise, not suffer a 20-dB clobber by an interfering buzzsaw signal.
>>My precerred approach, should I accept the assignement, would be to tap 
>>onto the I and Q baseband signals in the radio, chop at something like 
>>10 kHz and feed to the L and R inputs on a sound card. I can take it 
>>from there. My problemis that the SNR has become so degraded that the 
>>very good PLL in the radio doesn't lock up.
> But that requires a much more expensive receiver than a little OEM board
> with short ferrite rod. So my algorithm is designed to work with what I
> have which is just level transitions and times there of.
> JAB.

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