From phughes@clari.net Fri Jun 17 20:50:24 1994 Path: ashpoly!cascade!brgate!saturno!clari!phughes From: phughes@clari.net (Pavel Hughes) Newsgroups: comp.dsp Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Jun17.205024.1633@clari.net> Date: Fri, 17 Jun 1994 20:50:24 GMT Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: NewsWatcher 2.0b24 Lines: 11 Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. 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? -- Pavel Hughes Hayes Optima 288 @ 33,600 bps "In theory there is no difference between theory and practice." From mweber@unam.mx Sat Jun 18 11:33:24 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!unam!mweber From: mweber@unam.mx (Matthias Weber) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Jun18.113324.7796@unam.mx> Date: Sat, 18 Jun 1994 11:33:24 GMT References: <1994Jun17.205024.1633@clari.net> Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: Netscape 1.1N Lines: 10 In article <1994Jun17.205024.1633@clari.net>, phughes@clari.net (Pavel Hughes) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. > The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Matthias Weber "Row 14. No joke." Pentium 90 (OS/2 Warp) / NEXTSTEP 3.3 From ltakahashi@mindspring.com Sun Jun 19 03:41:24 1994 Path: ashpoly!cascade!bigsur!mindspring!ltakahashi From: ltakahashi@mindspring.com (Lucia Takahashi) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Jun19.034124.8668@mindspring.com> Date: Sun, 19 Jun 1994 03:41:24 GMT References: <1994Jun17.205024.1633@clari.net> <1994Jun18.113324.7796@unam.mx> Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1994Jun18.113324.7796@unam.mx>, mweber@unam.mx (Matthias Weber) writes: > Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Lucia Takahashi *PLONK* filter active for trolls. PC-9821Ap2 (NEC) - NetBSD 1.0