Noise reduction is a totally different process than noise blanking.
Noise blanking is for short and very strong pulses like ignition and
power line noise. The noise blaker, whether hardware or software detects
the pulses over a wide band to keep the detected pulse short, then shuts
off the receiver for that time period. The missed portion of the desired
signal usually isn't a problem. But if there are strong signals in the
blanker input passband but not in the desired receiver passband that
chopping of hole can turn the strong unwanted signal into broad band
noise. A noise blanker has no effect on normal background noise like
white noise and most antenna noise from world wide atmospherics.
Noise reduction is the nirvana of receiver performance wishing to reduce
that white noise and antenna noise but isn't effective at all on pulse
noise. There are several noise reduction techniques, some even work a
little. Many leave a residue of digital artifacts that isn't nearly as
random as white noise and that residue defeats our ear's noise
filtering. One other difficulty with using effective noise reduction is
the time delay from the processing makes tuning a receiver difficult.
73, Jerry, K0CQ
On 2/4/2011 11:11 AM, Thomas wrote:
Hi Jerry,
One fellow suggested that could be a contributor. I am not a big DSP noise
reduction fan as I found it to be nearly useless with my Omni VI+; granted
that was an early DSP application in amateur radio. Therefore, the original
noise issue I described with the Eagle was observed with noise reduction (NR)
turned off.
Thank you, Thomas
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