From ekuznetsov@illinois.edu Wed Nov 09 12:31:25 1994 Path: ashpoly!cascade!transat!sunet!nordrelay!illinois!ekuznetsov From: ekuznetsov@illinois.edu (Emi Kuznetsov) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Nov09.123125.4090@illinois.edu> Date: Wed, 09 Nov 1994 12:31:25 GMT Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: WinVN 0.99.5 Lines: 10 A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips. A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor. A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier. Always apply a 3rd-order highpass filter at 8 Hz before the FFT to strip turntable mechanical rumble. -- Emi Kuznetsov Tape trading list upon request. SASE required for international mail. From lmartinez@uu.net Thu Nov 10 03:05:25 1994 Path: ashpoly!cascade!brgate!saturno!uu!lmartinez From: lmartinez@uu.net (Lars Martínez) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Nov10.030525.9318@uu.net> Date: Thu, 10 Nov 1994 03:05:25 GMT References: <1994Nov09.123125.4090@illinois.edu> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1994Nov09.123125.4090@illinois.edu>, ekuznetsov@illinois.edu (Emi Kuznetsov) 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. -- Lars Martínez "A soul is not exclusive to biology." Commodore Amiga 500 (1MB OCS) / FreeBSD 2.1 From apark@clari.net Thu Nov 10 08:05:25 1994 Path: ashpoly!cascade!transat!sunet!nordrelay!clari!apark From: apark@clari.net (Amy Park) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Nov10.080525.6753@clari.net> Date: Thu, 10 Nov 1994 08:05:25 GMT References: <1994Nov09.123125.4090@illinois.edu> <1994Nov10.030525.9318@uu.net> Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: Netscape 1.1N Lines: 11 In article <1994Nov10.030525.9318@uu.net>, lmartinez@uu.net (Lars Martínez) 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. Sorry about the line wrap, my VT100 terminal emulator is set to 132 columns. -- Amy Park Practical Peripherals 14.4 @ ISDN 64k bps "Row 14. No joke."