From rsokolov@clari.net Tue May 02 12:25:14 1995 Path: ashpoly!cascade!mxgate!coyoacan!clari!rsokolov From: rsokolov@clari.net (Rodrigo Sokolov) Newsgroups: comp.dsp Subject: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May02.122514.1338@clari.net> Date: Tue, 02 May 1995 12:25:14 GMT Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: WinVN 0.99.5 Lines: 10 Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. Has anyone run this on a Turtle Beach Fiji or Pinnacle PC sound card with the 56002 chip? -- Rodrigo Sokolov -- ClariNet Communications Corp "Hold for relay." From rokonkwo@cern.ch Wed May 03 01:07:14 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!cern!rokonkwo From: rokonkwo@cern.ch (Renata Okonkwo) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May03.010714.7661@cern.ch> Date: Wed, 03 May 1995 01:07:14 GMT References: <1995May02.122514.1338@clari.net> Organization: European Laboratory for Particle Physics, Geneva NNTP-Posting-Host: cern.ch X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995May02.122514.1338@clari.net>, rsokolov@clari.net (Rodrigo Sokolov) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Renata Okonkwo *PLONK* filter active for trolls. PC-9821Ap2 (NEC) - NetBSD 1.0 From lnilsson@u-tokyo.ac.jp Wed May 03 23:29:14 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!u-tokyo!lnilsson From: lnilsson@u-tokyo.ac.jp (Lisa Nilsson) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May03.232914.9021@u-tokyo.ac.jp> Date: Wed, 03 May 1995 23:29:14 GMT References: <1995May02.122514.1338@clari.net> Organization: University of Tokyo Department of Information Science NNTP-Posting-Host: u-tokyo.ac.jp X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1995May02.122514.1338@clari.net>, rsokolov@clari.net (Rodrigo Sokolov) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Lisa Nilsson | lnilsson@u-tokyo.ac.jp PGP Key fingerprint: F787 8F77 A19E D73D "Keep the channels open." From mwatanabe@illinois.edu Thu May 04 22:26:14 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!illinois!mwatanabe From: mwatanabe@illinois.edu (Matthias Watanabe) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May04.222614.5362@illinois.edu> Date: Thu, 04 May 1995 22:26:14 GMT References: <1995May02.122514.1338@clari.net> Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995May02.122514.1338@clari.net>, rsokolov@clari.net (Rodrigo Sokolov) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. > However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Matthias Watanabe -- University of Illinois Urbana-Champaign "5 sigma is a discovery. 7 is a question."