From mcampbell@unam.mx Mon Apr 01 23:58:04 1996 Path: ashpoly!bigsur!pacrim!jpgate!kamome!unam!mcampbell From: mcampbell@unam.mx (Marisol Campbell) Newsgroups: comp.dsp Subject: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Apr01.235804.6691@unam.mx> Date: Mon, 01 Apr 1996 23:58:04 GMT Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: TIN [version 1.2 PL2] Lines: 11 Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor. 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. MATLAB script available upon request via email. -- Marisol Campbell *PLONK* filter active for trolls. Pentium 90 (OS/2 Warp) - NetBSD 1.0 From aduarte@netcom.com Tue Apr 02 18:43:04 1996 Path: ashpoly!cascade!transat!sunet!nordrelay!netcom!aduarte From: aduarte@netcom.com (Astrid Duarte) Newsgroups: comp.dsp Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Apr02.184304.9000@netcom.com> Date: Tue, 02 Apr 1996 18:43:04 GMT References: <1996Apr01.235804.6691@unam.mx> Organization: NETCOM On-Line Communication Services NNTP-Posting-Host: netcom.com X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1996Apr01.235804.6691@unam.mx>, mcampbell@unam.mx (Marisol Campbell) 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. -- Astrid Duarte Practical Peripherals 14.4 @ ISDN 64k bps "There are 14 nodes and only 10 countries. Count again."