From bgarcia@tum.de Fri May 12 03:43:54 1995 Path: ashpoly!cascade!mxgate!coyoacan!tum!bgarcia From: bgarcia@tum.de (Bill García) Newsgroups: comp.dsp Subject: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May12.034354.3002@tum.de> Date: Fri, 12 May 1995 03:43:54 GMT Organization: Technische Universität München NNTP-Posting-Host: tum.de X-Newsreader: WinVN 0.99.5 Lines: 10 Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample. Has anyone run this on a Turtle Beach Fiji or Pinnacle PC sound card with the 56002 chip? -- Bill García -- Technische Universität München "Measuring a record you own is listening, not piracy." From rlarsson@mit.edu Fri May 12 22:56:54 1995 Path: ashpoly!cascade!transat!ukc!fennimore!mit!rlarsson From: rlarsson@mit.edu (Rodrigo Larsson) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May12.225654.2240@mit.edu> Date: Fri, 12 May 1995 22:56:54 GMT References: <1995May12.034354.3002@tum.de> Organization: Massachusetts Institute of Technology NNTP-Posting-Host: mit.edu X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1995May12.034354.3002@tum.de>, bgarcia@tum.de (Bill García) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. > The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. -- Rodrigo Larsson Tape trading list upon request. SASE required for international mail. From mmoreno@ox.ac.uk Sun May 14 15:18:54 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!ox!mmoreno From: mmoreno@ox.ac.uk (Morag Moreno) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May14.151854.5679@ox.ac.uk> Date: Sun, 14 May 1995 15:18:54 GMT References: <1995May12.034354.3002@tum.de> <1995May12.225654.2240@mit.edu> Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: NewsWatcher 2.0b24 Lines: 11 In article <1995May12.225654.2240@mit.edu>, rlarsson@mit.edu (Rodrigo Larsson) writes: > Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! -- Morag Moreno *PLONK* filter active for trolls. 486DX2/66 (Linux 1.2.13) - NetBSD 1.0 From lmoreno@titech.ac.jp Mon May 15 04:01:54 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!titech!lmoreno From: lmoreno@titech.ac.jp (Lars Moreno) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995May15.040154.4216@titech.ac.jp> Date: Mon, 15 May 1995 04:01:54 GMT References: <1995May12.034354.3002@tum.de> <1995May12.225654.2240@mit.edu> Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: WinVN 0.99.5 Lines: 11 In article <1995May12.225654.2240@mit.edu>, rlarsson@mit.edu (Rodrigo Larsson) writes: > Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Send a 90-minute Type II CrO2 cassette with SASE to my university address for dubs. -- Lars Moreno | lmoreno@titech.ac.jp PGP Key fingerprint: 4A68 2B44 B0FB 4667 "Keep the channels open."