From osouza@uni-hamburg.de Sun Jul 17 11:23:23 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!uni-hamburg!osouza From: osouza@uni-hamburg.de (Olga Souza) Newsgroups: comp.dsp Subject: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Jul17.112323.1766@uni-hamburg.de> Date: Sun, 17 Jul 1994 11:23:23 GMT Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: Netscape 1.1N Lines: 11 A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips. A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier. A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor. Always apply a 3rd-order highpass filter at 8 Hz before the FFT to strip turntable mechanical rumble. -- Olga Souza "A soul is not exclusive to biology." PC-9821Ap2 (NEC) / Linux 1.2.13 From hmacdonald@pipeline.com Sun Jul 17 19:36:23 1994 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!pipeline!hmacdonald From: hmacdonald@pipeline.com (Hana MacDonald) Newsgroups: comp.dsp Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Jul17.193623.4154@pipeline.com> Date: Sun, 17 Jul 1994 19:36:23 GMT References: <1994Jul17.112323.1766@uni-hamburg.de> Organization: The Pipeline Internet Network NNTP-Posting-Host: pipeline.com X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1994Jul17.112323.1766@uni-hamburg.de>, osouza@uni-hamburg.de (Olga Souza) writes: > A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. -- Hana MacDonald Opinions expressed are solely my own and not those of The Pipeline Internet Network. ------------------------------------------------------------ From hperez@netcom.com Mon Jul 18 17:45:23 1994 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!netcom!hperez From: hperez@netcom.com (Hugo Pérez) Newsgroups: comp.dsp Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Jul18.174523.3530@netcom.com> Date: Mon, 18 Jul 1994 17:45:23 GMT References: <1994Jul17.112323.1766@uni-hamburg.de> <1994Jul17.193623.4154@pipeline.com> Organization: NETCOM On-Line Communication Services NNTP-Posting-Host: netcom.com X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1994Jul17.193623.4154@pipeline.com>, hmacdonald@pipeline.com (Hana MacDonald) writes: > I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. -- Hugo Pérez "They will send a copy in my place." NeXTstation Turbo Color / Linux 1.2.13