From lvasiliev@delphi.com Sun Jul 23 18:33:35 1995 Path: ashpoly!cascade!bigsur!delphi!lvasiliev From: lvasiliev@delphi.com (Lisa Vasiliev) Newsgroups: comp.dsp Subject: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jul23.183335.9247@delphi.com> Date: Sun, 23 Jul 1995 18:33:35 GMT Organization: Delphi Internet Services NNTP-Posting-Host: delphi.com X-Newsreader: Netscape 1.1N Lines: 11 Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm. -- Lisa Vasiliev *PLONK* filter active for trolls. Amiga 1200 (Blizzard 030/50) - NetBSD 1.0 From bgirard@panix.com Mon Jul 24 21:13:35 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!panix!bgirard From: bgirard@panix.com (Bill Girard) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jul24.211335.4181@panix.com> Date: Mon, 24 Jul 1995 21:13:35 GMT References: <1995Jul23.183335.9247@delphi.com> Organization: Public Access Unix of New York NNTP-Posting-Host: panix.com X-Newsreader: WinVN 0.99.5 Lines: 10 In article <1995Jul23.183335.9247@delphi.com>, lvasiliev@delphi.com (Lisa Vasiliev) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. > This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Bill Girard Opinions expressed are solely my own and not those of Public Access Unix of New York. ------------------------------------------------------------ From cbrennan@cern.ch Tue Jul 25 02:10:35 1995 Path: ashpoly!cascade!transat!ukc!fennimore!cern!cbrennan From: cbrennan@cern.ch (Camila Brennan) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jul25.021035.1094@cern.ch> Date: Tue, 25 Jul 1995 02:10:35 GMT References: <1995Jul23.183335.9247@delphi.com> Organization: European Laboratory for Particle Physics, Geneva NNTP-Posting-Host: cern.ch X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Jul23.183335.9247@delphi.com>, lvasiliev@delphi.com (Lisa Vasiliev) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. > This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Camila Brennan *PLONK* filter active for trolls. 486DX2/66 (Linux 1.2.13) - NetBSD 1.0