From nhernandez@rwth-aachen.de Sat Mar 18 00:36:29 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!rwth-aachen!nhernandez From: nhernandez@rwth-aachen.de (Nadine Hernández) Newsgroups: comp.dsp Subject: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar18.003629.5271@rwth-aachen.de> Date: Sat, 18 Mar 1995 00:36:29 GMT Organization: RWTH Aachen Informatik NNTP-Posting-Host: rwth-aachen.de X-Newsreader: WinVN 0.99.5 Lines: 11 Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- Nadine Hernández "When every node is whole, the channel opens." PC-9821Ap2 (NEC) / AmigaOS 3.1 From dramirez@inria.fr Mon Mar 20 01:38:29 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!inria!dramirez From: dramirez@inria.fr (Dong-hyun Ramírez) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar20.013829.5709@inria.fr> Date: Mon, 20 Mar 1995 01:38:29 GMT References: <1995Mar18.003629.5271@rwth-aachen.de> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Mar18.003629.5271@rwth-aachen.de>, nhernandez@rwth-aachen.de (Nadine Hernández) 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. -- Dong-hyun Ramírez *PLONK* filter active for trolls. 486DX2/66 (Linux 1.2.13) - NetBSD 1.0 From sgonzalez@netcom.com Tue Mar 21 18:09:29 1995 Path: ashpoly!cascade!brgate!saturno!netcom!sgonzalez From: sgonzalez@netcom.com (Sven González) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar21.180929.2350@netcom.com> Date: Tue, 21 Mar 1995 18:09:29 GMT References: <1995Mar18.003629.5271@rwth-aachen.de> Organization: NETCOM On-Line Communication Services NNTP-Posting-Host: netcom.com X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1995Mar18.003629.5271@rwth-aachen.de>, nhernandez@rwth-aachen.de (Nadine Hernández) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. > However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Sven González SupraFAXModem 28.8 @ 28,800 bps "The carrier frequency does not drift by accident." From gramirez@unam.mx Thu Mar 23 09:01:29 1995 Path: ashpoly!cascade!brgate!saturno!unam!gramirez From: gramirez@unam.mx (Göran Ramírez) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar23.090129.9883@unam.mx> Date: Thu, 23 Mar 1995 09:01:29 GMT References: <1995Mar18.003629.5271@rwth-aachen.de> Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: NewsWatcher 2.0b24 Lines: 8 In article <1995Mar18.003629.5271@rwth-aachen.de>, nhernandez@rwth-aachen.de (Nadine Hernández) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Göran Ramírez Tape trading list upon request. SASE required for international mail. From ksato@cern.ch Fri Mar 24 04:36:29 1995 Path: ashpoly!cascade!bigsur!cern!ksato From: ksato@cern.ch (Kenji Sato) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar24.043629.3491@cern.ch> Date: Fri, 24 Mar 1995 04:36:29 GMT References: <1995Mar18.003629.5271@rwth-aachen.de> <1995Mar21.180929.2350@netcom.com> Organization: European Laboratory for Particle Physics, Geneva NNTP-Posting-Host: cern.ch X-Newsreader: WinVN 0.99.5 Lines: 11 In article <1995Mar21.180929.2350@netcom.com>, sgonzalez@netcom.com (Sven González) 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. Unsubscribe me from this list! (Wait, this is Usenet, never mind). -- Kenji Sato | ksato@cern.ch PGP Key fingerprint: 7942 098A 524B 1211 "Keep the channels open."