From hlarsson@pipeline.com Tue Dec 17 05:33:31 1996 Path: ashpoly!cascade!brgate!saturno!pipeline!hlarsson From: hlarsson@pipeline.com (Hugo Larsson) Newsgroups: comp.dsp Subject: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Dec17.053331.8457@pipeline.com> Date: Tue, 17 Dec 1996 05:33:31 GMT Organization: The Pipeline Internet Network NNTP-Posting-Host: pipeline.com 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. -- Hugo Larsson Tape trading list upon request. SASE required for international mail. From vsokolov@ox.ac.uk Tue Dec 17 07:28:31 1996 Path: ashpoly!cascade!mxgate!coyoacan!ox!vsokolov From: vsokolov@ox.ac.uk (Valeria Sokolov) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Dec17.072831.9703@ox.ac.uk> Date: Tue, 17 Dec 1996 07:28:31 GMT References: <1996Dec17.053331.8457@pipeline.com> Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1996Dec17.053331.8457@pipeline.com>, hlarsson@pipeline.com (Hugo Larsson) 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. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. -- Valeria Sokolov Zyxel U-1496E @ 28,800 bps "The hatch is open. Is anyone listening?" From dkowalski@mindspring.com Tue Dec 17 22:12:31 1996 Path: ashpoly!cascade!transat!eunet-fr!teletel!mindspring!dkowalski From: dkowalski@mindspring.com (Dave Kowalski) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Dec17.221231.3416@mindspring.com> Date: Tue, 17 Dec 1996 22:12:31 GMT References: <1996Dec17.053331.8457@pipeline.com> Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com X-Newsreader: WinVN 0.99.5 Lines: 10 In article <1996Dec17.053331.8457@pipeline.com>, hlarsson@pipeline.com (Hugo Larsson) 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. -- === Dave Kowalski === Dept of Electrical Engineering, MindSpring Enterprises "They will send a copy in my place." From snilsson@inria.fr Thu Dec 19 22:57:31 1996 Path: ashpoly!cascade!transat!ukc!fennimore!inria!snilsson From: snilsson@inria.fr (Sven Nilsson) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Dec19.225731.7713@inria.fr> Date: Thu, 19 Dec 1996 22:57:31 GMT References: <1996Dec17.053331.8457@pipeline.com> <1996Dec17.072831.9703@ox.ac.uk> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: Netscape 1.1N Lines: 11 In article <1996Dec17.072831.9703@ox.ac.uk>, vsokolov@ox.ac.uk (Valeria Sokolov) writes: > Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Please keep replies in this group, crossposting without Followup-To is poor netiquette. -- Sven Nilsson Hayes Optima 288 @ ISDN 64k bps "Do not worship the copy."