Topband: Any Linrad selective limiter noise blanker experts here?

[W0MU Mike Fatchett]

The MFJ Noise canceler seems to work ok.  As a quick band aid for the 
contest.
  I have an AN4 and have never been very impressed with it.

W0MU

On 1/22/2020 4:34 AM, Tim Shoppa wrote:
> Rick, there are irregularities in my noise - and in the previous utility
> line noises I've had at my QTH - that prevent any
> predict-the-exact-time-of-the-noise-spike-in-advance algorithms.
>
> Although my sample size is small the experts have told me that randomly
> raucous 2-4 spikes every 120Hz I see is entirely typical of
> lightning arrestor faults.
>
> To show you the irregularities, here is the impulse envelope, recorded
> during daylight on 1.8MHz with a 20kHz wide filter and AM demodulator.
> Notice the overall 120Hz repetition, but inside that there is a
> substructure where evidently several arcs occur in the lightning arrestor
> each cycle and the exact number and timing of those vary from cycle to
> cycle:
>
> http://n3qe.org/n3qe-noise-structure.png
>
> And here is a short audio wav so you can hear some of raucous noise
> structure.
>
> http://n3qe.org/SDRSharp_20200120_210017Z_18050000Hz_AF.wav
>
> Tim N3QE
>
> On Tue, Jan 21, 2020 at 11:50 PM Richard (Rick) Karlquist <
> richard at karlquist.com> wrote:
>
>> The Kalman filter still generates a blanking pulse like the conventional
>> circuit.  Feedback loops adjust the width and timing of the blanking
>> pulse.  "Amplitude" is not applicable.  The frequency of the blanking
>> pulse is supplied from the power line in the shack (EG 60 Hz).  The
>> feedback loops average over many pulses and therefore suppress QRM
>> since it averages out in the long run.
>>
>> Again, this was all published many years ago.
>>
>> Rick N6RK
>>
>> On 1/21/2020 10:30 AM, Jim Brown wrote:
>>> On 1/20/2020 2:28 PM, Richard (Rick) Karlquist wrote:
>>>> In most cases, line noise is a repeating function with a frequency of
>>>> 50 or 60 Hz.  To make an  effective noise blanker in a contest, you
>>>> simply have to make a filter that only responds to harmonics of the
>>>> line frequency and then generate the inverse function from a 50 or
>>>> 60 Hz line clock.
>>> Unfortunately, that's too simple. For effective cancellation, that
>>> inverse function must be precisely in phase (degrees, not polarity) and
>>> equal in amplitude at each harmonic frequency.
>>>
>>> 73, Jim K9YC
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