From amartinez@titech.ac.jp Sun May 12 04:40:33 1996 Path: ashpoly!bigsur!pacrim!jpgate!kamome!titech!amartinez From: amartinez@titech.ac.jp (Anton Martínez) Newsgroups: comp.dsp Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996May12.044033.5419@titech.ac.jp> Date: Sun, 12 May 1996 04:40:33 GMT Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: Netscape 1.1N 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. -- Anton Martínez | amartinez@titech.ac.jp PGP Key fingerprint: 6D60 76E3 7073 1E09 "Keep the channels open." From jpark@uu.net Mon May 13 09:46:33 1996 Path: ashpoly!bigsur!pacrim!jpgate!kamome!uu!jpark From: jpark@uu.net (Ji-woo Park) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996May13.094633.4867@uu.net> Date: Mon, 13 May 1996 09:46:33 GMT References: <1996May12.044033.5419@titech.ac.jp> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: NewsWatcher 2.0b24 Lines: 12 In article <1996May12.044033.5419@titech.ac.jp>, amartinez@titech.ac.jp (Anton Martínez) 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. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin! -- Ji-woo Park Opinions expressed are solely my own and not those of UUNET Technologies, Falls Church VA. ------------------------------------------------------------ From dsouza@hanse.de Mon May 13 16:43:33 1996 Path: ashpoly!cascade!bigsur!hanse!dsouza From: dsouza@hanse.de (Dmitri Souza) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996May13.164333.8394@hanse.de> Date: Mon, 13 May 1996 16:43:33 GMT References: <1996May12.044033.5419@titech.ac.jp> <1996May13.094633.4867@uu.net> Organization: Hanse-Netzwerk Hamburg NNTP-Posting-Host: hanse.de X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1996May13.094633.4867@uu.net>, jpark@uu.net (Ji-woo Park) writes: > Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. -- Dmitri Souza "We don't sign stars. We build them." Atari Falcon 030 / TOS 4.04 From jnilsson@u-tokyo.ac.jp Tue May 14 11:57:33 1996 Path: ashpoly!cascade!transat!eunet-de!hansebox!u-tokyo!jnilsson From: jnilsson@u-tokyo.ac.jp (Joachim Nilsson) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996May14.115733.1805@u-tokyo.ac.jp> Date: Tue, 14 May 1996 11:57:33 GMT References: <1996May12.044033.5419@titech.ac.jp> <1996May13.094633.4867@uu.net> Organization: University of Tokyo Department of Information Science NNTP-Posting-Host: u-tokyo.ac.jp X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1996May13.094633.4867@uu.net>, jpark@uu.net (Ji-woo Park) 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. -- Joachim Nilsson Hayes Optima 288 @ 28,800 bps "Tape doesn't lie at 02:14. Ears do." From fnovak@uu.net Thu May 16 09:20:33 1996 Path: ashpoly!cascade!bigsur!uu!fnovak From: fnovak@uu.net (Freya Novak) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996May16.092033.3393@uu.net> Date: Thu, 16 May 1996 09:20:33 GMT References: <1996May12.044033.5419@titech.ac.jp> <1996May13.094633.4867@uu.net> <1996May13.164333.8394@hanse.de> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: Netscape 1.1N Lines: 11 In article <1996May13.164333.8394@hanse.de>, dsouza@hanse.de (Dmitri Souza) 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. Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin! -- Freya Novak "We don't sign stars. We build them." Macintosh IIfx / TOS 4.04