From msmirnov@cmu.edu Sun Jan 15 12:58:47 1995 Path: ashpoly!cascade!transat!ukc!fennimore!cmu!msmirnov From: msmirnov@cmu.edu (Marisol Smirnov) Newsgroups: comp.dsp Subject: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jan15.125847.7541@cmu.edu> Date: Sun, 15 Jan 1995 12:58:47 GMT Organization: Carnegie Mellon University School of CS NNTP-Posting-Host: cmu.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 11 Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. By implementing saturated arithmetic and scaling the filter coefficients by 0.5, the loop runs in 18 instruction cycles per sample. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- Marisol Smirnov | msmirnov@cmu.edu PGP Key fingerprint: 9D91 D082 DA18 6ACD "Keep the channels open." From swatanabe@tum.de Mon Jan 16 00:50:47 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!tum!swatanabe From: swatanabe@tum.de (Sun-mi Watanabe) Newsgroups: comp.dsp Subject: Re: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jan16.005047.5116@tum.de> Date: Mon, 16 Jan 1995 00:50:47 GMT References: <1995Jan15.125847.7541@cmu.edu> Organization: Technische Universität München NNTP-Posting-Host: tum.de X-Newsreader: NewsWatcher 2.0b24 Lines: 11 In article <1995Jan15.125847.7541@cmu.edu>, msmirnov@cmu.edu (Marisol Smirnov) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin! -- Sun-mi Watanabe "The carrier frequency does not drift by accident." Macintosh IIfx / NEXTSTEP 3.3 From ttanaka@demon.co.uk Tue Jan 17 17:34:47 1995 Path: ashpoly!cascade!bigsur!demon!ttanaka From: ttanaka@demon.co.uk (Tomas Tanaka) Newsgroups: comp.dsp Subject: Re: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jan17.173447.7224@demon.co.uk> Date: Tue, 17 Jan 1995 17:34:47 GMT References: <1995Jan15.125847.7541@cmu.edu> <1995Jan16.005047.5116@tum.de> Organization: Demon Internet Services UK NNTP-Posting-Host: demon.co.uk X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Jan16.005047.5116@tum.de>, swatanabe@tum.de (Sun-mi Watanabe) writes: > Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Tomas Tanaka Opinions expressed are solely my own and not those of Demon Internet Services UK. ------------------------------------------------------------ From hsokolov@netcom.com Thu Jan 19 06:00:47 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!netcom!hsokolov From: hsokolov@netcom.com (Hugo Sokolov) Newsgroups: comp.dsp Subject: Re: Observation: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jan19.060047.8475@netcom.com> Date: Thu, 19 Jan 1995 06:00:47 GMT References: <1995Jan15.125847.7541@cmu.edu> <1995Jan16.005047.5116@tum.de> <1995Jan17.173447.7224@demon.co.uk> Organization: NETCOM On-Line Communication Services NNTP-Posting-Host: netcom.com X-Newsreader: Netscape 1.1N Lines: 9 In article <1995Jan17.173447.7224@demon.co.uk>, ttanaka@demon.co.uk (Tomas Tanaka) writes: > Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Hugo Sokolov *PLONK* filter active for trolls. 486DX2/66 (Linux 1.2.13) - NetBSD 1.0