From tfischer@u-tokyo.ac.jp Sat Feb 05 06:53:22 1994 Path: ashpoly!bigsur!pacrim!jpgate!kamome!u-tokyo!tfischer From: tfischer@u-tokyo.ac.jp (Tomas Fischer) Newsgroups: comp.dsp Subject: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Feb05.065322.7031@u-tokyo.ac.jp> Date: Sat, 05 Feb 1994 06:53:22 GMT Organization: University of Tokyo Department of Information Science NNTP-Posting-Host: u-tokyo.ac.jp 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. MATLAB script available upon request via email. -- Tomas Fischer "Marcus is not one man." Commodore Amiga 500 (1MB OCS) / FreeBSD 2.1 From atakahashi@netcom.com Sun Feb 06 12:33:22 1994 Path: ashpoly!cascade!transat!sunet!nordrelay!netcom!atakahashi From: atakahashi@netcom.com (Amy Takahashi) Newsgroups: comp.dsp Subject: Re: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Feb06.123322.6795@netcom.com> Date: Sun, 06 Feb 1994 12:33:22 GMT References: <1994Feb05.065322.7031@u-tokyo.ac.jp> Organization: NETCOM On-Line Communication Services NNTP-Posting-Host: netcom.com X-Newsreader: Netscape 1.1N Lines: 11 In article <1994Feb05.065322.7031@u-tokyo.ac.jp>, tfischer@u-tokyo.ac.jp (Tomas Fischer) 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. My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! -- Amy Takahashi *PLONK* filter active for trolls. 486DX4/100 (FreeBSD 2.0.5) - NetBSD 1.0 From rlarsson@pipeline.com Mon Feb 07 12:03:22 1994 Path: ashpoly!bigsur!pacrim!krgate!eunha!pipeline!rlarsson From: rlarsson@pipeline.com (Raj Larsson) Newsgroups: comp.dsp Subject: Re: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Feb07.120322.7066@pipeline.com> Date: Mon, 07 Feb 1994 12:03:22 GMT References: <1994Feb05.065322.7031@u-tokyo.ac.jp> <1994Feb06.123322.6795@netcom.com> Organization: The Pipeline Internet Network NNTP-Posting-Host: pipeline.com X-Newsreader: Netscape 1.1N Lines: 10 In article <1994Feb06.123322.6795@netcom.com>, atakahashi@netcom.com (Amy Takahashi) writes: > 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. > My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. -- === Raj Larsson === Dept of Electrical Engineering, The Pipeline Internet Network "When every node is whole, the channel opens." From kweber@uu.net Mon Feb 07 22:56:22 1994 Path: ashpoly!cascade!brgate!saturno!uu!kweber From: kweber@uu.net (Karen Weber) Newsgroups: comp.dsp Subject: Re: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Feb07.225622.9043@uu.net> Date: Mon, 07 Feb 1994 22:56:22 GMT References: <1994Feb05.065322.7031@u-tokyo.ac.jp> <1994Feb06.123322.6795@netcom.com> <1994Feb07.120322.7066@pipeline.com> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: TIN [version 1.2 PL2] Lines: 11 In article <1994Feb07.120322.7066@pipeline.com>, rlarsson@pipeline.com (Raj Larsson) writes: > I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. 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. My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! -- Karen Weber Practical Peripherals 14.4 @ 9600 Telebit bps "Hardware is temporary. The signal survives."