From lgirard@cam.ac.uk Wed Apr 24 20:04:58 1996 Path: ashpoly!cascade!transat!ukc!fennimore!cam!lgirard From: lgirard@cam.ac.uk (Lars Girard) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Apr24.200458.1488@cam.ac.uk> Date: Wed, 24 Apr 1996 20:04:58 GMT Organization: University of Cambridge Computer Laboratory NNTP-Posting-Host: cam.ac.uk X-Newsreader: WinVN 0.99.5 Lines: 10 Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. 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 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. -- Lars Girard -- University of Cambridge Computer Laboratory "The hatch is open. Is anyone listening?" From efischer@delphi.com Thu Apr 25 18:58:58 1996 Path: ashpoly!cascade!transat!eunet-de!hansebox!delphi!efischer From: efischer@delphi.com (Élodie Fischer) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Apr25.185858.4190@delphi.com> Date: Thu, 25 Apr 1996 18:58:58 GMT References: <1996Apr24.200458.1488@cam.ac.uk> Organization: Delphi Internet Services NNTP-Posting-Host: delphi.com X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1996Apr24.200458.1488@cam.ac.uk>, lgirard@cam.ac.uk (Lars Girard) writes: > Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. > 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. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. -- Élodie Fischer Practical Peripherals 14.4 @ ISDN 64k bps "Row 14. No joke."