Return-Path: X-Spam-DCC: paranoid 1481; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: ** X-Spam-Status: No, score=2.7 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, FORGED_MUA_OUTLOOK,HTML_40_50,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 uA3MepTF029857 for ; Thu, 3 Nov 2016 23:40:52 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1c2QcZ-0008Eq-0H for rs_out_1@blacksheep.org; Thu, 03 Nov 2016 22:36:31 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1c2QcY-0008Eh-Jn for rsgb_lf_group@blacksheep.org; Thu, 03 Nov 2016 22:36:30 +0000 Received: from rgout0301.bt.lon5.cpcloud.co.uk ([65.20.0.207] helo=rgout03.bt.lon5.cpcloud.co.uk) by relay1.thorcom.net with esmtp (Exim 4.87) (envelope-from ) id 1c2QcV-0001R8-Ns for rsgb_lf_group@blacksheep.org; Thu, 03 Nov 2016 22:36:29 +0000 X-OWM-Source-IP: 86.178.51.135 (GB) X-OWM-Env-Sender: alan.melia@btinternet.com X-Junkmail-Premium-Raw: score=12/50,refid=2.7.2:2016.11.3.221517:17:12.731,ip=,rules=__HAS_MSGID, __SANE_MSGID, MSGID_32HEX_LC, INVALID_MSGID_NO_FQDN, __MSGID_32HEX, __HAS_FROM, __FRAUD_WEBMAIL_FROM, __TO_MALFORMED_2, __TO_NO_NAME, __REFERENCES, __BOUNCE_CHALLENGE_SUBJ, __BOUNCE_NDR_SUBJ_EXEMPT, __MIME_VERSION, __CT, __CTYPE_MULTIPART_ALT, __CTYPE_HAS_BOUNDARY, __CTYPE_MULTIPART, __HAS_X_PRIORITY, __HAS_MSMAIL_PRI, __HAS_X_MAILER, USER_AGENT_OE, __OUTLOOK_MUA_1, __USER_AGENT_MS_GENERIC, __MIME_TEXT_P2, __MIME_TEXT_H2, __ANY_URI, __FRAUD_BODY_WEBMAIL, __URI_NO_WWW, __CP_MEDIA_BODY, ECARD_WORD, __SUBJ_ALPHA_NEGATE, SUPERLONG_LINE, __HTML_AHREF_TAG, __HAS_HTML, HTML_TAG_NAME_RND_CAP, __HTML_TAG_DIV, HTML_NO_HTTP, BODY_SIZE_10000_PLUS, BODYTEXTH_SIZE_3000_MORE, BODYTEXTH_SIZE_10000_LESS, __MIME_TEXT_H1, __MIME_TEXT_P1, __MIME_HTML, __TAG_EXISTS_HTML, __FRAUD_WEBMAIL, __OUTLOOK_MUA, __MIME_TEXT_H, __MIME_TEXT_P, FORGED_MUA_OUTLOOK, REFERENCES, NO_URI_HTTPS Received: from gnat (86.178.51.135) by rgout03.bt.lon5.cpcloud.co.uk (9.0.019.07.01-1) (authenticated as alan.melia@btinternet.com) id 581B45AB000DBC97 for rsgb_lf_group@blacksheep.org; Thu, 3 Nov 2016 22:36:26 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=btinternet.com; s=btcpcloud; t=1478212587; bh=AGoz42vgeIAu3I5LUsASHVS/AZz81xRc5HQv4fTf67o=; h=Message-ID:From:To:References:Subject:Date:MIME-Version:X-Mailer; b=Gf1WW5vgd4IA/p+ilMzYDdvfrueugPZJFkES16e2JDmnsoKYTKsZvcLFLDnjwhgPyR16umUG4NAA13hD4v08aDQES5BoiN04QdVNR0J9n4hGe+VdqXl6hC7gGL5HOYvvpKEf08Pue5ZNHmJEw1WtYCK3Tz2TF9Gn4ntCu0FHk1Q= Message-ID: <47E490A24C8544289C92C8CD58CACDDA@gnat> From: "Alan Melia" To: References: <581B3A1F.5060609@posteo.de> <581B83FC.6060600@posteo.de> <22185768CF114BE0A22668E235A933A2@gnat> <9C401CC1F6BE43FFBE56056A1062B525@gnat> Date: Thu, 3 Nov 2016 22:28:49 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5931 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 X-Scan-Signature: b322dc0956bb435e223041a6879534f9 Subject: Re: LF: Smart noise cancelling?!? Content-Type: multipart/alternative; boundary="----=_NextPart_000_008A_01D23621.A61636A0" 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: 12109 Status: O X-Status: X-Keywords: X-UID: 9389 This is a multi-part message in MIME format. ------=_NextPart_000_008A_01D23621.A61636A0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Hi Andy yesI still have the ability to burn images to '128, 256, 512, = and 1000, UV roms.If you need or want an image blown. I kept mine in an = ISA motherboard :-)) it is the only machine that will handle some of the = older programmable PMR radios. some of those held the synth code in = PROM. I think I am just remembering maybe 10 years earlier than you :-)) I = played with "slow" FFTs written in Basic !! to try and get the hang of = filters and spectral effects, leakage and windowing were all very new = words to me in the early 80s. Once you see and understand the effects = you perhaps can get a better practical feel. Even then I was mainly = using my kit to do early exchange line-card testing. but quickly.=20 Still I'm getting boring so will quit. :-)) Alaan =20 ----- Original Message -----=20 From: Andy Talbot=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Thursday, November 03, 2016 9:10 PM Subject: Re: LF: Smart noise cancelling?!? 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.=20 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 :-)) =20 Alan G3NYK ----- Original Message -----=20 From: Andy Talbot=20 To: rsgb_lf_group@blacksheep.org=20 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=20 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.=20 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 =20 ------=_NextPart_000_008A_01D23621.A61636A0 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable =EF=BB=BF
Hi Andy yesI still have the ability to = burn images=20 to '128, 256, 512, and 1000, UV roms.If you need or want an image blown. = I=20 kept mine in an ISA motherboard :-)) it is the only machine that = will=20 handle some of the older programmable PMR radios. some of those held the = synth=20 code in PROM.
 
I think I am just remembering maybe 10 = years=20 earlier than you :-))  I played with "slow" FFTs written in Basic = !! to try=20 and get the hang of filters and spectral effects, leakage and = windowing=20 were all very new words to me in the early 80s. Once you see and = understand the=20 effects you perhaps can get a better practical feel. Even then I was = mainly=20 using my kit to do early exchange line-card testing. but=20 quickly. 
 
Still I'm getting boring so will quit.=20 :-))
 
Alaan
 
 
 
----- Original Message -----
From:=20 Andy=20 Talbot
Sent: Thursday, November 03, = 2016 9:10=20 PM
Subject: Re: LF: Smart noise=20 cancelling?!?

Not sure what you're saying, Alan
 By "narrow band filtering"   I actually DO mean the = digital=20 filtering applied in the FFT process.  It was the ability to go = down to=20 30 milli-Hz bandwidth and lower  that showed Peter the bursty = impulses=20 etc were being filtered to something that passed the tests for being=20 Gaussian

Back then the digitisation and first stages of decimation had to = be done=20 on external Motorola DSP cards, communicating with a PC for display = and=20 further slower decimation and filtering.

Programming  DSP chips in assembler was great fun then - far = more=20 interesting than doing it in high level code for soundcards

I still have three Motorola 56002EVM modules - doubt they're = worth=20 anything now ;-)    Blowing the 27128 EEPROMS they use to = store the=20 code is not that easy to do now - wonder if anyone kept their old = EEPROM=20 programmers?

Andy


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

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

We first ealised this in teh original QRSS tests with G3PLX = back in=20 the 1990's.   73kHz was full of spikes and 'crud' from teh = then=20 existing Decca signals and other stuff.   But when Peter = examined the=20 output from the narrow filters, (the FFT bins)  it lookdd = like, and=20 appeared to show itself to be Gaussian.   He said it passed = the tests=20 for Gaussian noise

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

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=20 bandwidth of the filter.

Andy  G4JNT

 

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