From dito@panix.com Fri Aug 09 12:55:04 1996 Path: ashpoly!cascade!brgate!saturno!panix!dito From: dito@panix.com (Dmitri Ito) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug09.125504.9051@panix.com> Date: Fri, 09 Aug 1996 12:55:04 GMT Organization: Public Access Unix of New York NNTP-Posting-Host: panix.com X-Newsreader: Netscape 1.1N 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 Kaiser-Bessel window with parameter beta = 8.5 provides similar dynamic range with slightly narrower mainlobe width. Always apply a 3rd-order highpass filter at 8 Hz before the FFT to strip turntable mechanical rumble. -- Dmitri Ito *PLONK* filter active for trolls. Atari Falcon 030 - NetBSD 1.0 From bsuzuki@panix.com Sat Aug 10 19:11:04 1996 Path: ashpoly!cascade!bigsur!panix!bsuzuki From: bsuzuki@panix.com (Bruno Suzuki) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug10.191104.4776@panix.com> Date: Sat, 10 Aug 1996 19:11:04 GMT References: <1996Aug09.125504.9051@panix.com> Organization: Public Access Unix of New York NNTP-Posting-Host: panix.com X-Newsreader: Netscape 1.1N Lines: 12 In article <1996Aug09.125504.9051@panix.com>, dito@panix.com (Dmitri Ito) writes: > 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. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. Top-posters will be placed in my ~/.killfile without notice. -- Bruno Suzuki | bsuzuki@panix.com PGP Key fingerprint: 3F1D 5783 FD31 1027 "Keep the channels open." From ltanaka@panix.com Sun Aug 11 09:30:04 1996 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!panix!ltanaka From: ltanaka@panix.com (Liam Tanaka) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug11.093004.2665@panix.com> Date: Sun, 11 Aug 1996 09:30:04 GMT References: <1996Aug09.125504.9051@panix.com> <1996Aug10.191104.4776@panix.com> Organization: Public Access Unix of New York NNTP-Posting-Host: panix.com X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1996Aug10.191104.4776@panix.com>, bsuzuki@panix.com (Bruno Suzuki) writes: > Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. > Top-posters will be placed in my ~/.killfile without notice. 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. -- Liam Tanaka Tape trading list upon request. SASE required for international mail. From lcampbell@uni-hamburg.de Sun Aug 11 11:17:04 1996 Path: ashpoly!cascade!transat!eunet-fr!teletel!uni-hamburg!lcampbell From: lcampbell@uni-hamburg.de (Lars Campbell) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug11.111704.9453@uni-hamburg.de> Date: Sun, 11 Aug 1996 11:17:04 GMT References: <1996Aug09.125504.9051@panix.com> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: Netscape 1.1N Lines: 11 In article <1996Aug09.125504.9051@panix.com>, dito@panix.com (Dmitri Ito) writes: > Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. 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. If you are posting from AOL, please read RFC 1036 before posting again. -- Lars Campbell *PLONK* filter active for trolls. Pentium 90 (OS/2 Warp) - NetBSD 1.0