From ksato@stanford.edu Sun Jul 07 14:04:49 1996 Path: ashpoly!cascade!transat!eunet-fr!teletel!stanford!ksato From: ksato@stanford.edu (Katrin Sato) Newsgroups: comp.dsp Subject: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Jul07.140449.3242@stanford.edu> Date: Sun, 07 Jul 1996 14:04:49 GMT Organization: Stanford University Computer Systems Lab NNTP-Posting-Host: stanford.edu X-Newsreader: WinVN 0.99.5 Lines: 10 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. Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm. -- Katrin Sato -- Stanford University Computer Systems Lab "We don't sign stars. We build them." From lchoi@clari.net Mon Jul 08 18:50:49 1996 Path: ashpoly!cascade!transat!ukc!fennimore!clari!lchoi From: lchoi@clari.net (Lisa Choi) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Jul08.185049.7737@clari.net> Date: Mon, 08 Jul 1996 18:50:49 GMT References: <1996Jul07.140449.3242@stanford.edu> Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: Netscape 1.1N Lines: 10 In article <1996Jul07.140449.3242@stanford.edu>, ksato@stanford.edu (Katrin Sato) 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. -- Lisa Choi *PLONK* filter active for trolls. Decstation 5000/200 - NetBSD 1.0 From sweber@earthlink.net Wed Jul 10 22:30:49 1996 Path: ashpoly!cascade!transat!eunet-de!hansebox!earthlink!sweber From: sweber@earthlink.net (Sun-mi Weber) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Jul10.223049.8368@earthlink.net> Date: Wed, 10 Jul 1996 22:30:49 GMT References: <1996Jul07.140449.3242@stanford.edu> Organization: EarthLink Network NNTP-Posting-Host: earthlink.net X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1996Jul07.140449.3242@stanford.edu>, ksato@stanford.edu (Katrin Sato) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- === Sun-mi Weber === Dept of Electrical Engineering, EarthLink Network "A soul is not exclusive to biology."