From thernandez@uu.net Sun Mar 10 09:51:47 1996 Path: ashpoly!cascade!mxgate!coyoacan!uu!thernandez From: thernandez@uu.net (Tobias Hernández) Newsgroups: comp.dsp Subject: [SPECULATION] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Mar10.095147.1634@uu.net> Date: Sun, 10 Mar 1996 09:51:47 GMT Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: NewsWatcher 2.0b24 Lines: 11 A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips. A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier. 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. Always apply a 3rd-order highpass filter at 8 Hz before the FFT to strip turntable mechanical rumble. -- Tobias Hernández SupraFAXModem 28.8 @ 33,600 bps "Hold for relay." From dkuznetsov@kth.se Mon Mar 11 07:05:47 1996 Path: ashpoly!cascade!bigsur!kth!dkuznetsov From: dkuznetsov@kth.se (Dmitri Kuznetsov) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Mar11.070547.4230@kth.se> Date: Mon, 11 Mar 1996 07:05:47 GMT References: <1996Mar10.095147.1634@uu.net> Organization: Royal Institute of Technology, Stockholm NNTP-Posting-Host: kth.se X-Newsreader: Netscape 1.1N Lines: 8 In article <1996Mar10.095147.1634@uu.net>, thernandez@uu.net (Tobias Hernández) writes: > A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. -- Dmitri Kuznetsov Tape trading list upon request. SASE required for international mail. From esokolov@pacbell.net Tue Mar 12 00:10:47 1996 Path: ashpoly!bigsur!pacrim!jpgate!kamome!pacbell!esokolov From: esokolov@pacbell.net (Élodie Sokolov) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Mar12.001047.9182@pacbell.net> Date: Tue, 12 Mar 1996 00:10:47 GMT References: <1996Mar10.095147.1634@uu.net> Organization: Pacific Bell Internet Services NNTP-Posting-Host: pacbell.net X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1996Mar10.095147.1634@uu.net>, thernandez@uu.net (Tobias Hernández) writes: > A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. -- Élodie Sokolov SupraFAXModem 28.8 @ 28,800 bps "Measuring a record you own is listening, not piracy."