Topband
[Top] [All Lists]

Re: Topband: Any Linrad selective limiter noise blanker experts here?

To: topBand List <topband@contesting.com>
Subject: Re: Topband: Any Linrad selective limiter noise blanker experts here?
From: Tim Shoppa <tshoppa@gmail.com>
Date: Wed, 22 Jan 2020 14:11:07 -0500
List-post: <mailto:topband@contesting.com>
AS AN UPDATE, N2NC and I are in communications regarding his Linrad noise
blanker settings and I am making some progress in learning how to
effectively adjust and operate the advanced noise blanker configuration and
settings. N2NC has a special version of Linrad where he has optimized the
displays to allow wise choice of limiting and noise blanking thresholds.
There are several waveforms and spectra to watch while making the
adjustments but it is actually kind of intuitive after just a little
practice.

So far all of this is all on fairly quiet bands and not contest conditions.
The real test will be if my noise is still happening (it does sometimes
disappear for a whole weekend, and it's possible Pepco will just fix it
still) during CQ 160 CW weekend as I try to actually use these new noise
blanking technologies in the dense spaced strong signal environment of the
contest.

Tim N3QE

On Mon, Jan 20, 2020 at 10:44 AM Tim Shoppa <tshoppa@gmail.com> wrote:

> My horrible utility line noise (which afflicted me in ARRL 160) continues
> and I'm looking to operate in the CQ 160 test this weekend and not be an
> alligator. I've located the offending pole but lack any way of getting it
> fixed on such short notice.
>
> In a quiet non-contest topband session, my rig's noise blanker does a very
> decent job eliminating the 120Hz impulses. I have to operate many kc away
> from any loud locals but it's effective. In a low-power contest like NAQP
> SSB the rigs noise blanker is still useful although not a cure-all.
>
> But in a 160 contest with a huge density of loud local signals, the rigs
> noise blanker's action just mixes all the super-loud dense signals together
> and isn't really effective anymore.
>
> I read in N2NC's NCJ article, about the powerful technique of using a SDR
> with Linrad configured to not apply the noise blanker to the loud signals.
> He goes on to say "The Linrad noise blanker, combined with the 768kHz
> bandwidth of the Airspy HF+, has been a big plus when the noise pops up. It
> makes the noise a non-issue, and I notice no distortion, even on a band
> packed with strong signals". N2NC's article here:
> https://ncjweb.com/bonus-content/N2NC-Linrad/N2NC-Linrad-Main.pdf
>
> Can any topbanders familiar with Linrad, please give me some hints on this
> configuration? Either on this list or by E-mail to me.
>
> Tim N3QE tshoppa@gmail.com
> _________________
> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

<Prev in Thread] Current Thread [Next in Thread>