[time-nuts] New WWVB modulation format receivers (NOT)

Bob Camp lists at rtty.us
Thu Feb 20 21:51:32 EST 2014


Hi

You can get parts in the 18 bit and up range for not a whole lot of money with rational sample rates for a WWVB receiver. Analog Devices and Linear Tech both make some interesting looking parts. They get you into the >=100 db  dynamic range area. 

Even with a lower bit count part, you pick up some bits in the downsampling process. As long as you have enough noise to keep things moving, you can track pretty far down into the crud. GPS receivers do that sort of thing all the time. 

Since this is slow audio after the CIC decimator, things like ARM chips probably have enough DSP horsepower to do what you need to do. The decimator it’s self is not terribly taxing if you don’t go too crazy with the rate change. 

Bob

On Feb 20, 2014, at 7:40 PM, Brian Lloyd <brian at lloyd.com> wrote:

> On Thursday, February 20, 2014, J. Forster <jfor at quikus.com> wrote:
> 
>> The large amplitude swings happen on a very short time scale too.
>> Certainly <1 second at times.
> 
> 
> 8-bits is 48 dB. 16-bit parts at 60kHz should be cheap now. Why bother with
> AGC? Just make sure the ADC doesn't clip.
> 
> <https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts>
> 
> 
> 
> -- 
> Brian Lloyd, WB6RQN/J79BPL
> 706 Flightline Drive
> Spring Branch, TX 78070
> brian at lloyd.com
> +1.916.877.5067
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