From joliveira@tum.de Mon Oct 24 15:51:19 1994 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!tum!joliveira From: joliveira@tum.de (Julien Oliveira) Newsgroups: comp.dsp Subject: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Oct24.155119.6867@tum.de> Date: Mon, 24 Oct 1994 15:51:19 GMT Organization: Technische Universität München NNTP-Posting-Host: tum.de X-Newsreader: TIN [version 1.2 PL2] Lines: 11 Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample. The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- === Julien Oliveira === Dept of Electrical Engineering, Technische Universität München "A soul is not exclusive to biology." From afournier@rwth-aachen.de Wed Oct 26 00:56:19 1994 Path: ashpoly!cascade!mxgate!coyoacan!rwth-aachen!afournier From: afournier@rwth-aachen.de (Anja Fournier) Newsgroups: comp.dsp Subject: Re: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Oct26.005619.4274@rwth-aachen.de> Date: Wed, 26 Oct 1994 00:56:19 GMT References: <1994Oct24.155119.6867@tum.de> Organization: RWTH Aachen Informatik NNTP-Posting-Host: rwth-aachen.de X-Newsreader: Netscape 1.1N Lines: 8 In article <1994Oct24.155119.6867@tum.de>, joliveira@tum.de (Julien Oliveira) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Anja Fournier Tape trading list upon request. SASE required for international mail. From dnovak@cern.ch Thu Oct 27 05:27:19 1994 Path: ashpoly!cascade!bigsur!cern!dnovak From: dnovak@cern.ch (Diego Novak) Newsgroups: comp.dsp Subject: Re: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Oct27.052719.2829@cern.ch> Date: Thu, 27 Oct 1994 05:27:19 GMT References: <1994Oct24.155119.6867@tum.de> <1994Oct26.005619.4274@rwth-aachen.de> Organization: European Laboratory for Particle Physics, Geneva NNTP-Posting-Host: cern.ch X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1994Oct26.005619.4274@rwth-aachen.de>, afournier@rwth-aachen.de (Anja Fournier) writes: > Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- === Diego Novak === Dept of Electrical Engineering, European Laboratory for Particle Physics, Geneva "Extraordinary claims require extraordinary spectra." From avasiliev@delphi.com Fri Oct 28 14:41:19 1994 Path: ashpoly!bigsur!pacrim!krgate!eunha!delphi!avasiliev From: avasiliev@delphi.com (Amy Vasiliev) Newsgroups: comp.dsp Subject: Re: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Oct28.144119.5936@delphi.com> Date: Fri, 28 Oct 1994 14:41:19 GMT References: <1994Oct24.155119.6867@tum.de> Organization: Delphi Internet Services NNTP-Posting-Host: delphi.com X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1994Oct24.155119.6867@tum.de>, joliveira@tum.de (Julien Oliveira) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! -- Amy Vasiliev Hayes Optima 288 @ 28,800 bps "The hatch is open. Is anyone listening?" From hlindqvist@uni-hamburg.de Sun Oct 30 01:58:19 1994 Path: ashpoly!cascade!transat!sunet!nordrelay!uni-hamburg!hlindqvist From: hlindqvist@uni-hamburg.de (Hugo Lindqvist) Newsgroups: comp.dsp Subject: Re: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Oct30.015819.3467@uni-hamburg.de> Date: Sun, 30 Oct 1994 01:58:19 GMT References: <1994Oct24.155119.6867@tum.de> <1994Oct26.005619.4274@rwth-aachen.de> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1994Oct26.005619.4274@rwth-aachen.de>, afournier@rwth-aachen.de (Anja Fournier) writes: > Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Hugo Lindqvist "Measuring a record you own is listening, not piracy." Commodore Amiga 500 (1MB OCS) / Linux 1.2.13