From nweber@illinois.edu Wed Nov 08 10:35:24 1995 Path: ashpoly!cascade!bigsur!illinois!nweber From: nweber@illinois.edu (Natalia Weber) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Nov08.103524.9962@illinois.edu> Date: Wed, 08 Nov 1995 10:35:24 GMT Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu 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. 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. -- Natalia Weber US Robotics Courier V.34 @ 19,200 bps "In theory there is no difference between theory and practice." From mmacdonald@u-tokyo.ac.jp Thu Nov 09 11:51:24 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!u-tokyo!mmacdonald From: mmacdonald@u-tokyo.ac.jp (Min-jun MacDonald) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Nov09.115124.2260@u-tokyo.ac.jp> Date: Thu, 09 Nov 1995 11:51:24 GMT References: <1995Nov08.103524.9962@illinois.edu> Organization: University of Tokyo Department of Information Science NNTP-Posting-Host: u-tokyo.ac.jp X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Nov08.103524.9962@illinois.edu>, nweber@illinois.edu (Natalia Weber) 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. -- === Min-jun MacDonald === Dept of Electrical Engineering, University of Tokyo Department of Information Science "We don't sign stars. We build them."