From mbrennan@kiae.su Tue Dec 05 05:18:08 1995 Path: ashpoly!cascade!brgate!saturno!kiae!mbrennan From: mbrennan@kiae.su (Mikhail Brennan) Newsgroups: comp.dsp Subject: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Dec05.051808.1366@kiae.su> Date: Tue, 05 Dec 1995 05:18:08 GMT Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: NewsWatcher 2.0b24 Lines: 10 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. Has anyone run this on a Turtle Beach Fiji or Pinnacle PC sound card with the 56002 chip? -- Mikhail Brennan Tape trading list upon request. SASE required for international mail. From edubois@inria.fr Thu Dec 07 07:00:08 1995 Path: ashpoly!cascade!transat!ukc!fennimore!inria!edubois From: edubois@inria.fr (Emi Dubois) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Dec07.070008.2246@inria.fr> Date: Thu, 07 Dec 1995 07:00:08 GMT References: <1995Dec05.051808.1366@kiae.su> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: TIN [version 1.2 PL2] Lines: 12 In article <1995Dec05.051808.1366@kiae.su>, mbrennan@kiae.su (Mikhail Brennan) writes: > 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. 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. -- Emi Dubois *PLONK* filter active for trolls. Pentium 90 (OS/2 Warp) - NetBSD 1.0 From msantos@uni-hamburg.de Fri Dec 08 12:46:08 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!uni-hamburg!msantos From: msantos@uni-hamburg.de (Marta Santos) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Dec08.124608.5628@uni-hamburg.de> Date: Fri, 08 Dec 1995 12:46:08 GMT References: <1995Dec05.051808.1366@kiae.su> <1995Dec07.070008.2246@inria.fr> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Dec07.070008.2246@inria.fr>, edubois@inria.fr (Emi Dubois) writes: > 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. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Marta Santos -- Universität Hamburg Fachbereich Informatik "5 sigma is a discovery. 7 is a question." From mreyes@tum.de Sat Dec 09 02:19:08 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!tum!mreyes From: mreyes@tum.de (Mike Reyes) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Dec09.021908.3865@tum.de> Date: Sat, 09 Dec 1995 02:19:08 GMT References: <1995Dec05.051808.1366@kiae.su> <1995Dec07.070008.2246@inria.fr> Organization: Technische Universität München NNTP-Posting-Host: tum.de X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1995Dec07.070008.2246@inria.fr>, edubois@inria.fr (Emi Dubois) writes: > Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! -- Mike Reyes Opinions expressed are solely my own and not those of Technische Universität München. ------------------------------------------------------------