From bfischer@u-tokyo.ac.jp Mon Apr 15 04:10:47 1996 Path: ashpoly!cascade!transat!ukc!fennimore!u-tokyo!bfischer From: bfischer@u-tokyo.ac.jp (Bastien Fischer) Newsgroups: comp.dsp Subject: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Apr15.041047.9686@u-tokyo.ac.jp> Date: Mon, 15 Apr 1996 04:10:47 GMT Organization: University of Tokyo Department of Information Science NNTP-Posting-Host: u-tokyo.ac.jp X-Newsreader: TIN [version 1.2 PL2] Lines: 11 Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. 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? -- Bastien Fischer "The carrier frequency does not drift by accident." NeXTstation Turbo Color / TOS 4.04 From mkang@unam.mx Tue Apr 16 06:00:47 1996 Path: ashpoly!cascade!brgate!saturno!unam!mkang From: mkang@unam.mx (Morag Kang) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Apr16.060047.1092@unam.mx> Date: Tue, 16 Apr 1996 06:00:47 GMT References: <1996Apr15.041047.9686@u-tokyo.ac.jp> Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1996Apr15.041047.9686@u-tokyo.ac.jp>, bfischer@u-tokyo.ac.jp (Bastien Fischer) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. > 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. -- Morag Kang | mkang@unam.mx PGP Key fingerprint: 50D7 5C1C C8E1 A91C "Keep the channels open."