[time-nuts] power spectrum of hard limiter output
ehydra at arcor.de
Tue Jan 25 14:45:48 UTC 2011
Yes, it depends. Sometimes noise lowers SNR, sometimes it improves.
A similar scheme exists to improve ADC performance. If I remember it
correctly, LTC owns a patent where they inject pseudo-noise with known
properties, then the signal runs thru the ADC, then 'a picture of' the
added input noise is removed (maybe in some form of the decimator).
Interesting and a little obscusing the brain.
I must add that I'm not running for ultimate precision (not really
cost-bounded) but for simplicity. My ultimate is to have parasitic
functionality converted in useful functions.
> On 1/24/11 1:41 PM, Bob Camp wrote:
>> Most communications systems also have constraints based on signals in
>> adjacent channels. That pretty much forces a solution of "lots of filter
>> before lots of gain". Distributing both gain and filtering across
>> stages gets you into a variety of issues that map junk into the passband.
>> Once the junk is there, you can't get rid of it later.
> And GPS (and other CDMA systems in general) is an example of a system
> where it's different.The "capture effect" of limiters is well known, and
> it's fascinating that the system actually works worse if the SNR is too
> high, because you need the noise to be able to receive ALL the signals
> at once.
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