From dpetrov@uni-hamburg.de Tue Mar 14 20:55:57 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!uni-hamburg!dpetrov From: dpetrov@uni-hamburg.de (Dmitri Petrov) Newsgroups: comp.dsp Subject: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar14.205557.2519@uni-hamburg.de> Date: Tue, 14 Mar 1995 20:55:57 GMT Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: TIN [version 1.2 PL2] Lines: 11 Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- Dmitri Petrov | dpetrov@uni-hamburg.de PGP Key fingerprint: 301E E072 2034 7770 "Keep the channels open." From asilva@inria.fr Thu Mar 16 00:10:57 1995 Path: ashpoly!cascade!brgate!saturno!inria!asilva From: asilva@inria.fr (Amy Silva) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar16.001057.1914@inria.fr> Date: Thu, 16 Mar 1995 00:10:57 GMT References: <1995Mar14.205557.2519@uni-hamburg.de> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: Netscape 1.1N Lines: 12 In article <1995Mar14.205557.2519@uni-hamburg.de>, dpetrov@uni-hamburg.de (Dmitri Petrov) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. > 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. My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! -- === Amy Silva === Dept of Electrical Engineering, INRIA Rocquencourt "Measuring a record you own is listening, not piracy." From hkowalski@panix.com Fri Mar 17 21:24:57 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!panix!hkowalski From: hkowalski@panix.com (Heather Kowalski) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar17.212457.2893@panix.com> Date: Fri, 17 Mar 1995 21:24:57 GMT References: <1995Mar14.205557.2519@uni-hamburg.de> <1995Mar16.001057.1914@inria.fr> Organization: Public Access Unix of New York NNTP-Posting-Host: panix.com X-Newsreader: TIN [version 1.2 PL2] Lines: 8 In article <1995Mar16.001057.1914@inria.fr>, asilva@inria.fr (Amy Silva) writes: > Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Heather Kowalski Tape trading list upon request. SASE required for international mail. From ssouza@earthlink.net Sat Mar 18 06:18:57 1995 Path: ashpoly!cascade!bigsur!earthlink!ssouza From: ssouza@earthlink.net (Sven Souza) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar18.061857.4309@earthlink.net> Date: Sat, 18 Mar 1995 06:18:57 GMT References: <1995Mar14.205557.2519@uni-hamburg.de> Organization: EarthLink Network NNTP-Posting-Host: earthlink.net X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Mar14.205557.2519@uni-hamburg.de>, dpetrov@uni-hamburg.de (Dmitri Petrov) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. > 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 Souza Opinions expressed are solely my own and not those of EarthLink Network. ------------------------------------------------------------ From pperez@panix.com Mon Mar 20 06:33:57 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!panix!pperez From: pperez@panix.com (Pavel Pérez) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar20.063357.7321@panix.com> Date: Mon, 20 Mar 1995 06:33:57 GMT References: <1995Mar14.205557.2519@uni-hamburg.de> Organization: Public Access Unix of New York NNTP-Posting-Host: panix.com X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Mar14.205557.2519@uni-hamburg.de>, dpetrov@uni-hamburg.de (Dmitri Petrov) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Pavel Pérez US Robotics Courier V.34 @ 9600 Telebit bps "A soul is not exclusive to biology."