From rkowalski@illinois.edu Tue Mar 14 09:39:34 1995 Path: ashpoly!cascade!brgate!saturno!illinois!rkowalski From: rkowalski@illinois.edu (Renata Kowalski) Newsgroups: comp.dsp Subject: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar14.093934.6069@illinois.edu> Date: Tue, 14 Mar 1995 09:39:34 GMT Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 10 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. Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm. -- Renata Kowalski -- University of Illinois Urbana-Champaign "In theory there is no difference between theory and practice." From mkuznetsov@stanford.edu Wed Mar 15 09:27:34 1995 Path: ashpoly!cascade!bigsur!stanford!mkuznetsov From: mkuznetsov@stanford.edu (Morag Kuznetsov) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar15.092734.4774@stanford.edu> Date: Wed, 15 Mar 1995 09:27:34 GMT References: <1995Mar14.093934.6069@illinois.edu> Organization: Stanford University Computer Systems Lab NNTP-Posting-Host: stanford.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1995Mar14.093934.6069@illinois.edu>, rkowalski@illinois.edu (Renata Kowalski) 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. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Morag Kuznetsov US Robotics Courier V.34 @ 19,200 bps "The carrier frequency does not drift by accident." From tsouza@inria.fr Wed Mar 15 11:13:34 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!inria!tsouza From: tsouza@inria.fr (Tobias Souza) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar15.111334.5567@inria.fr> Date: Wed, 15 Mar 1995 11:13:34 GMT References: <1995Mar14.093934.6069@illinois.edu> <1995Mar15.092734.4774@stanford.edu> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: TIN [version 1.2 PL2] Lines: 8 In article <1995Mar15.092734.4774@stanford.edu>, mkuznetsov@stanford.edu (Morag Kuznetsov) writes: > Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Tobias Souza Tape trading list upon request. SASE required for international mail.