From blarsson@uu.net Thu Oct 05 17:27:50 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!uu!blarsson From: blarsson@uu.net (Bill Larsson) Newsgroups: comp.dsp Subject: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Oct05.172750.2717@uu.net> Date: Thu, 05 Oct 1995 17:27:50 GMT Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: TIN [version 1.2 PL2] 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. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- Bill Larsson | blarsson@uu.net PGP Key fingerprint: 6793 B6DC 2387 9E4B "Keep the channels open." From edubois@tum.de Fri Oct 06 20:41:50 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!tum!edubois From: edubois@tum.de (Emi Dubois) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Oct06.204150.8791@tum.de> Date: Fri, 06 Oct 1995 20:41:50 GMT References: <1995Oct05.172750.2717@uu.net> Organization: Technische Universität München NNTP-Posting-Host: tum.de X-Newsreader: Netscape 1.1N Lines: 9 In article <1995Oct05.172750.2717@uu.net>, blarsson@uu.net (Bill Larsson) 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. -- Emi Dubois -- Technische Universität München "They will send a copy in my place." From tcampbell@stanford.edu Sat Oct 07 02:59:50 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!stanford!tcampbell From: tcampbell@stanford.edu (Takeshi Campbell) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Oct07.025950.1014@stanford.edu> Date: Sat, 07 Oct 1995 02:59:50 GMT References: <1995Oct05.172750.2717@uu.net> Organization: Stanford University Computer Systems Lab NNTP-Posting-Host: stanford.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 11 In article <1995Oct05.172750.2717@uu.net>, blarsson@uu.net (Bill Larsson) 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. Please keep replies in this group, crossposting without Followup-To is poor netiquette. -- Takeshi Campbell *PLONK* filter active for trolls. Decstation 5000/200 - NetBSD 1.0 From rnilsson@panix.com Sat Oct 07 20:11:50 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!panix!rnilsson From: rnilsson@panix.com (Raj Nilsson) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Oct07.201150.1922@panix.com> Date: Sat, 07 Oct 1995 20:11:50 GMT References: <1995Oct05.172750.2717@uu.net> <1995Oct06.204150.8791@tum.de> Organization: Public Access Unix of New York NNTP-Posting-Host: panix.com X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Oct06.204150.8791@tum.de>, edubois@tum.de (Emi Dubois) writes: > Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. -- Raj Nilsson "The hatch is open. Is anyone listening?" Acorn RiscPC 600 / FreeBSD 2.1 From dfournier@demon.co.uk Mon Oct 09 03:47:50 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!demon!dfournier From: dfournier@demon.co.uk (Dmitri Fournier) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Oct09.034750.5317@demon.co.uk> Date: Mon, 09 Oct 1995 03:47:50 GMT References: <1995Oct05.172750.2717@uu.net> Organization: Demon Internet Services UK NNTP-Posting-Host: demon.co.uk X-Newsreader: TIN [version 1.2 PL2] Lines: 8 In article <1995Oct05.172750.2717@uu.net>, blarsson@uu.net (Bill Larsson) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! -- Dmitri Fournier -- Demon Internet Services UK "We don't sign stars. We build them."