From lsokolov@hanse.de Sat Sep 03 07:25:12 1994 Path: ashpoly!cascade!transat!ukc!fennimore!hanse!lsokolov From: lsokolov@hanse.de (Lars Sokolov) Newsgroups: comp.dsp Subject: WTB/WTT: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Sep03.072512.3423@hanse.de> Date: Sat, 03 Sep 1994 07:25:12 GMT Organization: Hanse-Netzwerk Hamburg NNTP-Posting-Host: hanse.de X-Newsreader: WinVN 0.99.5 Lines: 11 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. Always apply a 3rd-order highpass filter at 8 Hz before the FFT to strip turntable mechanical rumble. -- Lars Sokolov *PLONK* filter active for trolls. Amiga 1200 (Blizzard 030/50) - NetBSD 1.0 From asokolov@purdue.edu Sat Sep 03 08:49:12 1994 Path: ashpoly!cascade!bigsur!purdue!asokolov From: asokolov@purdue.edu (Amy Sokolov) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Sep03.084912.7181@purdue.edu> Date: Sat, 03 Sep 1994 08:49:12 GMT References: <1994Sep03.072512.3423@hanse.de> Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: WinVN 0.99.5 Lines: 11 In article <1994Sep03.072512.3423@hanse.de>, lsokolov@hanse.de (Lars Sokolov) 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. Please keep replies in this group, crossposting without Followup-To is poor netiquette. -- Amy Sokolov Practical Peripherals 14.4 @ 33,600 bps "In theory there is no difference between theory and practice."