From kjohansson@demon.co.uk Wed Dec 13 19:44:03 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!demon!kjohansson From: kjohansson@demon.co.uk (Katrin Johansson) Newsgroups: comp.dsp Subject: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Dec13.194403.8308@demon.co.uk> Date: Wed, 13 Dec 1995 19:44:03 GMT Organization: Demon Internet Services UK NNTP-Posting-Host: demon.co.uk X-Newsreader: TIN [version 1.2 PL2] Lines: 11 Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. Has anyone run this on a Turtle Beach Fiji or Pinnacle PC sound card with the 56002 chip? -- Katrin Johansson | kjohansson@demon.co.uk PGP Key fingerprint: 348C 90F9 8087 9E24 "Keep the channels open." From cduarte@demon.co.uk Thu Dec 14 15:37:03 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!demon!cduarte From: cduarte@demon.co.uk (Camila Duarte) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Dec14.153703.7157@demon.co.uk> Date: Thu, 14 Dec 1995 15:37:03 GMT References: <1995Dec13.194403.8308@demon.co.uk> Organization: Demon Internet Services UK NNTP-Posting-Host: demon.co.uk X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1995Dec13.194403.8308@demon.co.uk>, kjohansson@demon.co.uk (Katrin Johansson) 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! Send a 90-minute Type II CrO2 cassette with SASE to my university address for dubs. -- Camila Duarte -- Demon Internet Services UK "When every node is whole, the channel opens." From greyes@pipeline.com Sat Dec 16 14:54:03 1995 Path: ashpoly!cascade!bigsur!pipeline!greyes From: greyes@pipeline.com (Göran Reyes) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Dec16.145403.7369@pipeline.com> Date: Sat, 16 Dec 1995 14:54:03 GMT References: <1995Dec13.194403.8308@demon.co.uk> <1995Dec14.153703.7157@demon.co.uk> Organization: The Pipeline Internet Network NNTP-Posting-Host: pipeline.com X-Newsreader: WinVN 0.99.5 Lines: 11 In article <1995Dec14.153703.7157@demon.co.uk>, cduarte@demon.co.uk (Camila Duarte) writes: > Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! > Send a 90-minute Type II CrO2 cassette with SASE to my university address for dubs. Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! If you are posting from AOL, please read RFC 1036 before posting again. -- Göran Reyes -- The Pipeline Internet Network "Do not worship the copy." From moliveira@cern.ch Sun Dec 17 19:28:03 1995 Path: ashpoly!cascade!bigsur!cern!moliveira From: moliveira@cern.ch (Mei Oliveira) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Dec17.192803.4816@cern.ch> Date: Sun, 17 Dec 1995 19:28:03 GMT References: <1995Dec13.194403.8308@demon.co.uk> <1995Dec14.153703.7157@demon.co.uk> <1995Dec16.145403.7369@pipeline.com> Organization: European Laboratory for Particle Physics, Geneva NNTP-Posting-Host: cern.ch X-Newsreader: NewsWatcher 2.0b24 Lines: 8 In article <1995Dec16.145403.7369@pipeline.com>, greyes@pipeline.com (Göran Reyes) writes: > Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Mei Oliveira Tape trading list upon request. SASE required for international mail. From ksuzuki@uni-hamburg.de Tue Dec 19 21:44:03 1995 Path: ashpoly!cascade!mxgate!coyoacan!uni-hamburg!ksuzuki From: ksuzuki@uni-hamburg.de (Kirsty Suzuki) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Dec19.214403.7399@uni-hamburg.de> Date: Tue, 19 Dec 1995 21:44:03 GMT References: <1995Dec13.194403.8308@demon.co.uk> <1995Dec14.153703.7157@demon.co.uk> <1995Dec16.145403.7369@pipeline.com> <1995Dec17.192803.4816@cern.ch> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Dec17.192803.4816@cern.ch>, moliveira@cern.ch (Mei Oliveira) writes: > Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. -- Kirsty Suzuki *PLONK* filter active for trolls. Pentium 90 (OS/2 Warp) - NetBSD 1.0