From bnakamura@clari.net Fri Jan 26 12:20:24 1996 Path: ashpoly!cascade!brgate!saturno!clari!bnakamura From: bnakamura@clari.net (Brian Nakamura) Newsgroups: comp.dsp Subject: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Jan26.122024.1645@clari.net> Date: Fri, 26 Jan 1996 12:20:24 GMT Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: Netscape 1.1N 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. Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm. -- Brian Nakamura Practical Peripherals 14.4 @ 9600 Telebit bps "When every node is whole, the channel opens." From adubois@ox.ac.uk Sat Jan 27 21:02:24 1996 Path: ashpoly!cascade!transat!eunet-de!hansebox!ox!adubois From: adubois@ox.ac.uk (Andrei Dubois) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Jan27.210224.7672@ox.ac.uk> Date: Sat, 27 Jan 1996 21:02:24 GMT References: <1996Jan26.122024.1645@clari.net> Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1996Jan26.122024.1645@clari.net>, bnakamura@clari.net (Brian Nakamura) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. -- === Andrei Dubois === Dept of Electrical Engineering, Oxford University Computing Laboratory "Measuring a record you own is listening, not piracy." From mito@kiae.su Sun Jan 28 22:43:24 1996 Path: ashpoly!cascade!transat!ukc!fennimore!kiae!mito From: mito@kiae.su (Mateo Ito) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Jan28.224324.2525@kiae.su> Date: Sun, 28 Jan 1996 22:43:24 GMT References: <1996Jan26.122024.1645@clari.net> Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: WinVN 0.99.5 Lines: 8 In article <1996Jan26.122024.1645@clari.net>, bnakamura@clari.net (Brian Nakamura) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. -- Mateo Ito -- Kurchatov Institute of Atomic Energy, Moscow "Row 14. No joke." From lgarcia@illinois.edu Tue Jan 30 09:08:24 1996 Path: ashpoly!cascade!transat!eunet-de!hansebox!illinois!lgarcia From: lgarcia@illinois.edu (Lucia García) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Jan30.090824.4028@illinois.edu> Date: Tue, 30 Jan 1996 09:08:24 GMT References: <1996Jan26.122024.1645@clari.net> <1996Jan28.224324.2525@kiae.su> Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1996Jan28.224324.2525@kiae.su>, mito@kiae.su (Mateo Ito) writes: > Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Lucia García Opinions expressed are solely my own and not those of University of Illinois Urbana-Champaign. ------------------------------------------------------------