Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, HTML_MESSAGE,RCVD_IN_DNSWL_MED,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: : mailn 1480; Body=2 Fuz1=2 Fuz2=2 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by lipkowski.org (8.14.4/8.14.4/Debian-8+deb8u1) with ESMTP id v57GqxKu008386 for ; Wed, 7 Jun 2017 18:53:00 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1dIe7c-0002Cb-2W for rs_out_1@blacksheep.org; Wed, 07 Jun 2017 17:47:52 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1dIe7Z-0002CS-5Y for rsgb_lf_group@blacksheep.org; Wed, 07 Jun 2017 17:47:49 +0100 Received: from mout02.posteo.de ([185.67.36.66]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1dIe7V-00058i-J5 for rsgb_lf_group@blacksheep.org; Wed, 07 Jun 2017 17:47:47 +0100 Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id 6E98B2098D for ; Wed, 7 Jun 2017 18:47:44 +0200 (CEST) Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 3wjZH26NN6z10Hk for ; Wed, 7 Jun 2017 18:47:42 +0200 (CEST) Message-ID: <59382E2E.5000306@posteo.de> Date: Wed, 07 Jun 2017 18:47:42 +0200 From: DK7FC User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <15c8347d971-adf-3549f@webprd-m73.mail.aol.com> In-Reply-To: <15c8347d971-adf-3549f@webprd-m73.mail.aol.com> X-Scan-Signature: c0e6e8bcdc231effb9da2003d606d9a2 Subject: Re: LF: Bugfix for ebnaut_ifft utility Content-Type: multipart/alternative; boundary="------------060005060500030202020503" 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 2.75 Status: RO X-Status: X-Keywords: X-UID: 11918 This is a multi-part message in MIME format. --------------060005060500030202020503 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Thanks Markus, What does minor SNR degradation mean, in dB, and on what does this value depend? (e.g. transmission time, symbol length, etc). 73, Stefan Am 07.06.2017 17:59, schrieb Markus Vester: > > Dear EbNauteers, > > I recently stumbled upon a bug in my ebnaut_ifft3a utility, which is > used to convert SpecLab FFT export files to IQ wav files. The first > step of the inverse FFT is to take the complex conjugate of the data > array. Due to the bug, the respective loop was executed only N-1 > times, leaving a sign error in the imaginary part of a single bin next > to the center frequency. When fed with a high-SNR signal close to > SpecLab's center frequency, this can produce strange undulation > patterns in the phase display and a minor SNR degradation for the decoder. > > The bug has been fixed in version 3b, available on > http://df6nm.bplaced.net/VLF/fec_tests/ebnaut_ifft3b.zip > > Best regards, > Markus (DF6NM) > --------------060005060500030202020503 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit Thanks Markus,

What does minor SNR degradation mean, in dB, and on what does this value depend? (e.g. transmission time, symbol length, etc).

73, Stefan

Am 07.06.2017 17:59, schrieb Markus Vester:

Dear EbNauteers,

I recently stumbled upon a bug in my ebnaut_ifft3a utility, which is used to convert SpecLab FFT export files to IQ wav files. The first step of the inverse FFT is to take the complex conjugate of the data array. Due to the bug, the respective loop was executed only N-1 times, leaving a sign error in the imaginary part of a single bin next to the center frequency. When fed with a high-SNR signal close to SpecLab's center frequency, this can produce strange undulation patterns in the phase display and a minor SNR degradation for the decoder.

The bug has been fixed in version 3b, available on
http://df6nm.bplaced.net/VLF/fec_tests/ebnaut_ifft3b.zip

Best regards,
Markus (DF6NM)

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