From pivanov@mit.edu Sun Jun 05 20:12:30 1994 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!mit!pivanov From: pivanov@mit.edu (Pavel Ivanov) Newsgroups: comp.dsp Subject: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Jun05.201230.5753@mit.edu> Date: Sun, 05 Jun 1994 20:12:30 GMT Organization: Massachusetts Institute of Technology NNTP-Posting-Host: mit.edu X-Newsreader: WinVN 0.99.5 Lines: 10 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. 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. -- Pavel Ivanov Tape trading list upon request. SASE required for international mail. From ifischer@cam.ac.uk Mon Jun 06 20:47:30 1994 Path: ashpoly!cascade!brgate!saturno!cam!ifischer From: ifischer@cam.ac.uk (Ines Fischer) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Jun06.204730.2124@cam.ac.uk> Date: Mon, 06 Jun 1994 20:47:30 GMT References: <1994Jun05.201230.5753@mit.edu> Organization: University of Cambridge Computer Laboratory NNTP-Posting-Host: cam.ac.uk X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1994Jun05.201230.5753@mit.edu>, pivanov@mit.edu (Pavel Ivanov) writes: > 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. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Ines Fischer "Marcus is not one man." Commodore Amiga 500 (1MB OCS) / AmigaOS 3.1