From apark@cam.ac.uk Tue May 17 15:15:26 1994 Path: ashpoly!cascade!transat!eunet-fr!teletel!cam!apark From: apark@cam.ac.uk (Andrei Park) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994May17.151526.1261@cam.ac.uk> Date: Tue, 17 May 1994 15:15:26 GMT Organization: University of Cambridge Computer Laboratory NNTP-Posting-Host: cam.ac.uk X-Newsreader: NewsWatcher 2.0b24 Lines: 11 Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. 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. -- Andrei Park *PLONK* filter active for trolls. 486DX4/100 (FreeBSD 2.0.5) - NetBSD 1.0 From dramirez@unam.mx Wed May 18 07:36:26 1994 Path: ashpoly!cascade!transat!sunet!nordrelay!unam!dramirez From: dramirez@unam.mx (Dong-hyun Ramírez) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994May18.073626.9743@unam.mx> Date: Wed, 18 May 1994 07:36:26 GMT References: <1994May17.151526.1261@cam.ac.uk> Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: Netscape 1.1N Lines: 10 In article <1994May17.151526.1261@cam.ac.uk>, apark@cam.ac.uk (Andrei Park) writes: > Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. > A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. -- === Dong-hyun Ramírez === Dept of Electrical Engineering, Universidad Nacional Autónoma de México (DGSCA) "They will send a copy in my place." From onilsson@uu.net Thu May 19 09:20:26 1994 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!uu!onilsson From: onilsson@uu.net (Olga Nilsson) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994May19.092026.2625@uu.net> Date: Thu, 19 May 1994 09:20:26 GMT References: <1994May17.151526.1261@cam.ac.uk> <1994May18.073626.9743@unam.mx> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1994May18.073626.9743@unam.mx>, dramirez@unam.mx (Dong-hyun Ramírez) 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. -- Olga Nilsson "Row 14. No joke." Pentium 90 (OS/2 Warp) / AmigaOS 3.1