It wouldn't put me to sleep...I love that stuff, too!
Ron
N6AHA
----- Original Message -----
From: "Lin Davis" <linbdavis@earthlink.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Wednesday, March 01, 2006 2:56 PM
Subject: Re: [TenTec] [Orion] Orion II Noise Blankers
> Hi Grant,
>
> I've done a bit of research into DSP filtering and even called Gary at
> Ten-Tec
> to find out what the NR filter implementation is.
>
> And you are correct, it is certainly not just a form of an expansion
> circuit!!
>
> By Doug Smith, it's called an adaptive predictor. The theory behind it was
> developed 40+ years ago by Kalman, who based his work on Wiener and
> Kolmogoroff.
> To me, it's pretty cool stuff.
>
> But unfortunately, I still thing the manual description of it's behavior
> is in
> need of an update. I was hoping to contact Mr. Smith to help me understand
> it
> better, since he has most likely coded and played with it.
>
> I'll follow up with more details soon. And hopefully that post won't put
> too
> many folks out there to sleep :)
>
> 73,
> Lin
> WB1AIW
>
> Grant Youngman wrote:
>
>>
>>
>>>but I DO still hear a difference. I can only conclude from
>>>this that there is no adaption component to the NR function,
>>>and therefore the NR value is not controlling an adaption
>>>rate, but something else, which sounds to me to be an
>>>amplitude threshold.
>>
>>
>> We seem to be talking around each other, but there's no reason to believe
>> NR
>> level is controlling some simple threshold.
>>
>> All I can suggest you do is take it up with Gary at T-T for a definitive
>> answer straight from the proverbial horses mouth :-)
>>
>> My take on it, based on experience and T-T's own description is that:
>>
>> 1. It's adaptive
>> 2. It builds dynamic filters around signal spectral components
>> 3. Since the filters are dynamic, they are built and rebuilt as the
>> apparent spectral components change in the bandpass, at a rate determined
>> by
>> the NR setting. (I'm not saying this is precisely the mechanism, but it
>> is
>> the effect of the mechanism. T-T has not published, that I'm aware of,
>> the
>> specific algorithms employed).
>> 4. The closer the signal amplitude gets to the noise level, the longer
>> adaption will take -- and in some cases, it may not take at all, in which
>> case, turn it off or turn down the THRESHOLD level or turn up the RF
>> gain.
>> And if that doesn't work, then turn it off.
>> 5. It's primary function is to improve S/N ratio, not provide a "noise
>> free" environment for listening enjoyment :-)
>>
>> Note that I am not making statements about how WELL it works, or doesn't.
>> Many seem to think it worked better in 1.371 and earlier releases than
>> the
>> current realization in 2.xxx.
>>
>> Grant/NQ5T
>>
>>
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>>
>>
>
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