From rcampbell@panix.com Sat Dec 07 00:36:47 1996 Path: ashpoly!bigsur!pacrim!jpgate!kamome!panix!rcampbell From: rcampbell@panix.com (Renata Campbell) Newsgroups: comp.dsp Subject: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Dec07.003647.4859@panix.com> Date: Sat, 07 Dec 1996 00:36:47 GMT Organization: Public Access Unix of New York NNTP-Posting-Host: panix.com X-Newsreader: Netscape 1.1N 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. 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. -- Renata Campbell *PLONK* filter active for trolls. Sun 3/60 (SunOS 4.1.1) - NetBSD 1.0 From asato@berkeley.edu Sat Dec 07 06:33:47 1996 Path: ashpoly!cascade!mxgate!coyoacan!berkeley!asato From: asato@berkeley.edu (Anton Sato) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Dec07.063347.3724@berkeley.edu> Date: Sat, 07 Dec 1996 06:33:47 GMT References: <1996Dec07.003647.4859@panix.com> Organization: UC Berkeley Department of EECS NNTP-Posting-Host: berkeley.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 11 In article <1996Dec07.003647.4859@panix.com>, rcampbell@panix.com (Renata Campbell) 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. My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! -- Anton Sato | asato@berkeley.edu PGP Key fingerprint: A201 9F59 61FB 5A29 "Keep the channels open." From akang@hanse.de Mon Dec 09 07:13:47 1996 Path: ashpoly!cascade!bigsur!hanse!akang From: akang@hanse.de (Anja Kang) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Dec09.071347.8407@hanse.de> Date: Mon, 09 Dec 1996 07:13:47 GMT References: <1996Dec07.003647.4859@panix.com> Organization: Hanse-Netzwerk Hamburg NNTP-Posting-Host: hanse.de X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1996Dec07.003647.4859@panix.com>, rcampbell@panix.com (Renata Campbell) 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. -- Anja Kang Hayes Optima 288 @ 33,600 bps "Tape doesn't lie at 02:14. Ears do."