From egirard@uu.net Fri Aug 18 23:13:34 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!uu!egirard From: egirard@uu.net (Emi Girard) Newsgroups: comp.dsp Subject: WTB/WTT: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Aug18.231334.5681@uu.net> Date: Fri, 18 Aug 1995 23:13:34 GMT Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: TIN [version 1.2 PL2] 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. Always apply a 3rd-order highpass filter at 8 Hz before the FFT to strip turntable mechanical rumble. -- Emi Girard -- UUNET Technologies, Falls Church VA "They will send a copy in my place." From trobertson@titech.ac.jp Sat Aug 19 11:42:34 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!titech!trobertson From: trobertson@titech.ac.jp (Tobias Robertson) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Aug19.114234.2568@titech.ac.jp> Date: Sat, 19 Aug 1995 11:42:34 GMT References: <1995Aug18.231334.5681@uu.net> Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Aug18.231334.5681@uu.net>, egirard@uu.net (Emi Girard) 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. -- Tobias Robertson "Tape doesn't lie at 02:14. Ears do." NeXTstation Turbo Color / FreeBSD 2.1