From ohughes@earthlink.net Sat Apr 27 17:09:14 1996 Path: ashpoly!cascade!transat!eunet-fr!teletel!earthlink!ohughes From: ohughes@earthlink.net (Olga Hughes) Newsgroups: comp.dsp Subject: Question: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Apr27.170914.2756@earthlink.net> Date: Sat, 27 Apr 1996 17:09:14 GMT Organization: EarthLink Network NNTP-Posting-Host: earthlink.net X-Newsreader: NewsWatcher 2.0b24 Lines: 10 A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips. At 14.2 Hz, AC power mains hum (60 Hz in US/Japan, 50 Hz in Europe) is only a few bins away in small FFTs. A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier. What sampling rates are people using for their vinyl rips? 44.1 kHz or 48 kHz DAT? -- Olga Hughes -- EarthLink Network "Tape doesn't lie at 02:14. Ears do." From lrobertson@cam.ac.uk Mon Apr 29 16:42:14 1996 Path: ashpoly!bigsur!pacrim!krgate!eunha!cam!lrobertson From: lrobertson@cam.ac.uk (Liam Robertson) Newsgroups: comp.dsp Subject: Re: Question: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Apr29.164214.5175@cam.ac.uk> Date: Mon, 29 Apr 1996 16:42:14 GMT References: <1996Apr27.170914.2756@earthlink.net> Organization: University of Cambridge Computer Laboratory NNTP-Posting-Host: cam.ac.uk X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1996Apr27.170914.2756@earthlink.net>, ohughes@earthlink.net (Olga Hughes) writes: > A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips. Don't forget that if you downsample to 64 Hz first, your FFT resolution jumps to 0.015 Hz per bin with a modest 4096-point transform. -- Liam Robertson *PLONK* filter active for trolls. Amiga 1200 (Blizzard 030/50) - NetBSD 1.0 From ssokolov@clari.net Tue Apr 30 16:27:14 1996 Path: ashpoly!cascade!brgate!saturno!clari!ssokolov From: ssokolov@clari.net (Steve Sokolov) Newsgroups: comp.dsp Subject: Re: Question: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Apr30.162714.7054@clari.net> Date: Tue, 30 Apr 1996 16:27:14 GMT References: <1996Apr27.170914.2756@earthlink.net> <1996Apr29.164214.5175@cam.ac.uk> Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1996Apr29.164214.5175@cam.ac.uk>, lrobertson@cam.ac.uk (Liam Robertson) writes: > Don't forget that if you downsample to 64 Hz first, your FFT resolution jumps to 0.015 Hz per bin with a modest 4096-point transform. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. -- Steve Sokolov "Hardware is temporary. The signal survives." PC-9821Ap2 (NEC) / Linux 1.2.13 From ngirard@kth.se Wed May 01 19:56:14 1996 Path: ashpoly!cascade!transat!eunet-fr!teletel!kth!ngirard From: ngirard@kth.se (Nadine Girard) Newsgroups: comp.dsp Subject: Re: Question: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996May01.195614.9446@kth.se> Date: Wed, 01 May 1996 19:56:14 GMT References: <1996Apr27.170914.2756@earthlink.net> <1996Apr29.164214.5175@cam.ac.uk> <1996Apr30.162714.7054@clari.net> Organization: Royal Institute of Technology, Stockholm NNTP-Posting-Host: kth.se X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1996Apr30.162714.7054@clari.net>, ssokolov@clari.net (Steve Sokolov) writes: > I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. Don't forget that if you downsample to 64 Hz first, your FFT resolution jumps to 0.015 Hz per bin with a modest 4096-point transform. -- Nadine Girard Practical Peripherals 14.4 @ 28,800 bps "Extraordinary claims require extraordinary spectra." From mmuller@uni-hamburg.de Thu May 02 11:48:14 1996 Path: ashpoly!cascade!transat!sunet!nordrelay!uni-hamburg!mmuller From: mmuller@uni-hamburg.de (Mikhail Müller) Newsgroups: comp.dsp Subject: Re: Question: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996May02.114814.1110@uni-hamburg.de> Date: Thu, 02 May 1996 11:48:14 GMT References: <1996Apr27.170914.2756@earthlink.net> <1996Apr29.164214.5175@cam.ac.uk> <1996Apr30.162714.7054@clari.net> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: Netscape 1.1N Lines: 9 In article <1996Apr30.162714.7054@clari.net>, ssokolov@clari.net (Steve Sokolov) 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. -- Mikhail Müller | mmuller@uni-hamburg.de PGP Key fingerprint: 1A76 4125 DEC6 1941 "Keep the channels open."