From skowalski@clari.net Tue Mar 15 21:55:25 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!clari!skowalski From: skowalski@clari.net (Sergei Kowalski) Newsgroups: comp.dsp Subject: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Mar15.215525.9713@clari.net> Date: Tue, 15 Mar 1994 21:55:25 GMT Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: WinVN 0.99.5 Lines: 11 Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. 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. -- Sergei Kowalski | skowalski@clari.net PGP Key fingerprint: 9829 9029 8B81 7D32 "Keep the channels open." From ikarlsson@berkeley.edu Thu Mar 17 01:36:25 1994 Path: ashpoly!bigsur!pacrim!jpgate!kamome!berkeley!ikarlsson From: ikarlsson@berkeley.edu (Ines Karlsson) Newsgroups: comp.dsp Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Mar17.013625.7094@berkeley.edu> Date: Thu, 17 Mar 1994 01:36:25 GMT References: <1994Mar15.215525.9713@clari.net> Organization: UC Berkeley Department of EECS NNTP-Posting-Host: berkeley.edu X-Newsreader: Netscape 1.1N Lines: 11 In article <1994Mar15.215525.9713@clari.net>, skowalski@clari.net (Sergei Kowalski) writes: > Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! -- Ines Karlsson Practical Peripherals 14.4 @ 9600 Telebit bps "Marcus is not one man." From dsanchez@utexas.edu Fri Mar 18 20:32:25 1994 Path: ashpoly!cascade!transat!sunet!nordrelay!utexas!dsanchez From: dsanchez@utexas.edu (Diego Sánchez) Newsgroups: comp.dsp Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Mar18.203225.7037@utexas.edu> Date: Fri, 18 Mar 1994 20:32:25 GMT References: <1994Mar15.215525.9713@clari.net> <1994Mar17.013625.7094@berkeley.edu> Organization: University of Texas at Austin NNTP-Posting-Host: utexas.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1994Mar17.013625.7094@berkeley.edu>, ikarlsson@berkeley.edu (Ines Karlsson) writes: > Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. -- Diego Sánchez | dsanchez@utexas.edu PGP Key fingerprint: 9E63 408D 2855 137A "Keep the channels open."