Return-Path: X-Spam-DCC: paranoid 1481; Body=3 Fuz1=3 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-1.5 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_30_40,HTML_MESSAGE,PLING_QUERY,SPF_PASS autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id uA3LESdh029682 for ; Thu, 3 Nov 2016 22:14:28 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1c2PHq-00086B-LG for rs_out_1@blacksheep.org; Thu, 03 Nov 2016 21:11:02 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1c2PHq-000862-9G for rsgb_lf_group@blacksheep.org; Thu, 03 Nov 2016 21:11:02 +0000 Received: from mail-wm0-x22d.google.com ([2a00:1450:400c:c09::22d]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.87) (envelope-from ) id 1c2PHn-00016h-FV for rsgb_lf_group@blacksheep.org; Thu, 03 Nov 2016 21:11:01 +0000 Received: by mail-wm0-x22d.google.com with SMTP id n67so12378192wme.1 for ; Thu, 03 Nov 2016 14:10:59 -0700 (PDT) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to; bh=nriOnZsSmlmBMj+CwLcyBJ1cGJDrcWGC0M21n/VW628=; b=kqVfhJRcOpIiKvW7TDnnIiKgyhTvNOnCPieZW5zppIhw2lR9/VxS9oHua7uR5UXQVj noov0K2wYjiIxIPQtPxnRBm1HbCy905snVGpYHUNYDMi+iT+U0j2FrXAoC5e8qt1T+ry DDX1ECSn5f4PKf26OlDzU8tUJbOBLZtK1wXOx9jSy7GMVUC+oVxCx9fTo18aA2aPdzbi OMWqcA0cf4sHLaCptb+FO5kupeSZWGHKZ/M+z9l6xX2lb55T+BeYHm7+izpa/pIOyzsr MJEy93h4xRGOCd0TORGOebmh/iAcEwscSeHGVhlBHb8FPDbsXk0ZevzWf68XuDfHGcvn e7jQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to; bh=nriOnZsSmlmBMj+CwLcyBJ1cGJDrcWGC0M21n/VW628=; b=iDsyGy3GNdV63qhcEa8FPHLFl/E33tagUg9GgAh645Ebp1qE2UAkY7ElB7L9NgD8gY c8d+tlvJPZ8fNvKctwOMGMw46UqbidDl2n8bYMKzXEi77gbe7pVBPmKPJGAh6NM+vMYJ OFveIWqzl1KCKz0n+8Hjw6KiPc1RLA8Z85y+KR5Oyr7g/x+aQ4IXycpS5x789IwZ7AUP fS/1Ruwe342EosFzN3xolalv7jQ7kEeaK4CkpnBnnIqxBkBMjmed9QlqWLMcCYqGQPf4 plV/9/cvJlv26BRH9sI5ZLhPesIeWTR0yucVviVaVgnLvNMnO/FMZtrGg8jHH7wKxMUJ ATJA== X-Gm-Message-State: ABUngveX21PZxk0UJqU3vOVR0cZDkrT/TMAY1oZCuwHB6Blj/wy+u6X0SwsvyrEsHAtt+QhkoG5pflan0U7QZw== X-Received: by 10.194.240.129 with SMTP id wa1mr8807199wjc.116.1478207457810; Thu, 03 Nov 2016 14:10:57 -0700 (PDT) MIME-Version: 1.0 Received: by 10.28.209.74 with HTTP; Thu, 3 Nov 2016 14:10:57 -0700 (PDT) In-Reply-To: <9C401CC1F6BE43FFBE56056A1062B525@gnat> References: <581B3A1F.5060609@posteo.de> <581B83FC.6060600@posteo.de> <22185768CF114BE0A22668E235A933A2@gnat> <9C401CC1F6BE43FFBE56056A1062B525@gnat> From: Andy Talbot Date: Thu, 3 Nov 2016 21:10:57 +0000 Message-ID: To: rsgb_lf_group@blacksheep.org X-Scan-Signature: 7c995d39cde70605aa76dd18810a4256 Subject: Re: LF: Smart noise cancelling?!? Content-Type: multipart/alternative; boundary=089e013d1db26d60a705406bfe57 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Scanned-By: MIMEDefang 2.56 on 10.1.3.11 Content-Length: 8237 Status: O X-Status: X-Keywords: X-UID: 9388 --089e013d1db26d60a705406bfe57 Content-Type: text/plain; charset=UTF-8 Not sure what you're saying, Alan By "narrow band filtering" I actually DO mean the digital filtering applied in the FFT process. It was the ability to go down to 30 milli-Hz bandwidth and lower that showed Peter the bursty impulses etc were being filtered to something that passed the tests for being Gaussian Back then the digitisation and first stages of decimation had to be done on external Motorola DSP cards, communicating with a PC for display and further slower decimation and filtering. Programming DSP chips in assembler was great fun then - far more interesting than doing it in high level code for soundcards I still have three Motorola 56002EVM modules - doubt they're worth anything now ;-) Blowing the 27128 EEPROMS they use to store the code is not that easy to do now - wonder if anyone kept their old EEPROM programmers? Andy On 3 November 2016 at 20:47, Alan Melia wrote: > Hi Andy things have changed since then. Real time FFTs were just beginning > to be possible but not many had much experience at that time. I remember > the cleverest stuff I saw was from a graduate student. It closed down some > more traditional work, like an adaptive modem in weeks. Guessing from the > comments on the latest modes now I think there seems to be little left to > achieve in efficiency. > > Most of us were still thinking in analogue ways then :-)) "Just 'cos it > digital doesn't mean its better" I heard a number of times....we were to be > converted ! > > Of course a well respected physicist opined in 1900 that there was little > new left to discover in the field. Fortunately for me and the rest of the > profession, he was slightly wrong :-)) > > Alan > G3NYK > > > > > > ----- Original Message ----- > *From:* Andy Talbot > *To:* rsgb_lf_group@blacksheep.org > *Sent:* Thursday, November 03, 2016 7:45 PM > *Subject:* Re: LF: Smart noise cancelling?!? > > But surely, when narrowband filtering is in place - as any narrow band > mode will of necessity be doing internally - any wideband non Gaussian or > bursty noise when applied to this narrow filter will eventually become > Gaussian IN THAT BANDWIDTH > > We first ealised this in teh original QRSS tests with G3PLX back in the > 1990's. 73kHz was full of spikes and 'crud' from teh then existing Decca > signals and other stuff. But when Peter examined the output from the > narrow filters, (the FFT bins) it lookdd like, and appeared to show itself > to be Gaussian. He said it passed the tests for Gaussian noise > > A mathematician could probably prove that any random non Gaussian signal > if filtered sufficiently narrow in comparison to itsnature, would end up > Gaussian in the filtered bandwidth. > > In fact, to end up non-Gaussian, it would have to have definite components > repeating at rates very close to the reciprocal of the bandwidth of the > filter. > > Andy G4JNT > > > > --089e013d1db26d60a705406bfe57 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Not sure what you're saying, Alan
=C2=A0By "n= arrow band filtering" =C2=A0 I actually DO mean the digital filtering = applied in the FFT process.=C2=A0 It was the ability to go down to 30 milli= -Hz bandwidth and lower =C2=A0that showed Peter the bursty impulses etc wer= e being filtered to something that passed the tests for being Gaussian

Back then the digitisation and first stages of decimat= ion had to be done on external Motorola DSP cards, communicating with a PC = for display and further slower decimation and filtering.

Programming =C2=A0DSP chips in assembler was great fun then - far mo= re interesting than doing it in high level code for soundcards

I still have three Motorola 56002EVM modules - doubt they&= #39;re worth anything now ;-) =C2=A0 =C2=A0Blowing the 27128 EEPROMS they u= se to store the code is not that easy to do now - wonder if anyone kept the= ir old EEPROM programmers?

Andy


On 3 Nove= mber 2016 at 20:47, Alan Melia <alan.melia@btinternet.com><= /span> wrote:
Hi Andy things have changed since then= . Real time=20 FFTs were just beginning to be possible but not many had much experience at= that=20 time. I remember the cleverest stuff I saw was from a graduate student. It= =20 closed down some more traditional work, like an adaptive modem=C2=A0in week= s.=20 Guessing from the comments on the latest modes now=C2=A0I think there seems= to=20 be little left to achieve in efficiency.
=C2=A0
Most of us were still thinking in anal= ogue ways=20 then :-))=C2=A0 "Just 'cos it digital doesn't mean its better&= quot; I heard a number=20 of times....we were to be converted !
=C2=A0
Of course a well respected physicist o= pined in 1900=20 that there was little new left to discover in the field. Fortunately for me= and=20 the rest of the profession, he was slightly wrong :-))=C2=A0
=C2=A0
Alan
G3NYK
=C2=A0
=C2=A0
=C2=A0
=C2=A0
----- Original Message -----
From:=20 Andy=20 Talbot
Sent: Thursday, November 03, 2016 7= :45=20 PM
Subject: Re: LF: Smart noise=20 cancelling?!?

But surely, when narrowband filtering is in place - as a= ny narrow=20 band mode will of necessity be doing internally - any wideband non Gaussi= an or=20 bursty noise when applied to this narrow filter will eventually become=20 Gaussian IN THAT BANDWIDTH

We first ealised this in teh original QRSS tests with G3PLX back in = the=20 1990's. =C2=A0 73kHz was full of spikes and 'crud' from teh t= hen existing=20 Decca signals and other stuff. =C2=A0 But when Peter examined the output = from=20 the narrow filters, (the FFT bins) =C2=A0it lookdd like, and appeared to = show=20 itself to be Gaussian. =C2=A0 He said it passed the tests for Gaussian=20 noise

A mathematician could probably prove that any random non Gaussian si= gnal=20 if filtered sufficiently narrow in comparison to itsnature, would end up= =20 Gaussian in the filtered bandwidth.=C2=A0

In fact, to end up non-Gaussian, it would have to have definite=20 components repeating at rates very close to the reciprocal of the bandwid= th of=20 the filter.

Andy =C2=A0G4JNT

=C2=A0

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