From aokonkwo@mindspring.com Thu Jul 27 09:15:20 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!mindspring!aokonkwo From: aokonkwo@mindspring.com (Andrei Okonkwo) Newsgroups: comp.dsp Subject: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jul27.091520.5740@mindspring.com> Date: Thu, 27 Jul 1995 09:15:20 GMT Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com X-Newsreader: NewsWatcher 2.0b24 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. -- Andrei Okonkwo Opinions expressed are solely my own and not those of MindSpring Enterprises. ------------------------------------------------------------ From tkowalski@purdue.edu Sat Jul 29 12:37:20 1995 Path: ashpoly!cascade!mxgate!coyoacan!purdue!tkowalski From: tkowalski@purdue.edu (Takeshi Kowalski) Newsgroups: comp.dsp Subject: Re: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jul29.123720.7465@purdue.edu> Date: Sat, 29 Jul 1995 12:37:20 GMT References: <1995Jul27.091520.5740@mindspring.com> Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: Netscape 1.1N Lines: 9 In article <1995Jul27.091520.5740@mindspring.com>, aokonkwo@mindspring.com (Andrei Okonkwo) 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. -- Takeshi Kowalski -- Purdue University Engineering Computer Network "Row 14. No joke." From jito@rwth-aachen.de Sun Jul 30 00:06:20 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!rwth-aachen!jito From: jito@rwth-aachen.de (Joachim Ito) Newsgroups: comp.dsp Subject: Re: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jul30.000620.3663@rwth-aachen.de> Date: Sun, 30 Jul 1995 00:06:20 GMT References: <1995Jul27.091520.5740@mindspring.com> <1995Jul29.123720.7465@purdue.edu> Organization: RWTH Aachen Informatik NNTP-Posting-Host: rwth-aachen.de X-Newsreader: TIN [version 1.2 PL2] Lines: 8 In article <1995Jul29.123720.7465@purdue.edu>, tkowalski@purdue.edu (Takeshi Kowalski) writes: > Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Joachim Ito Tape trading list upon request. SASE required for international mail. From mcampbell@berkeley.edu Mon Jul 31 09:29:20 1995 Path: ashpoly!cascade!bigsur!berkeley!mcampbell From: mcampbell@berkeley.edu (Mateo Campbell) Newsgroups: comp.dsp Subject: Re: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jul31.092920.7042@berkeley.edu> Date: Mon, 31 Jul 1995 09:29:20 GMT References: <1995Jul27.091520.5740@mindspring.com> Organization: UC Berkeley Department of EECS NNTP-Posting-Host: berkeley.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Jul27.091520.5740@mindspring.com>, aokonkwo@mindspring.com (Andrei Okonkwo) 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. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Mateo Campbell -- UC Berkeley Department of EECS "Marcus is not one man." From dsouza@inria.fr Tue Aug 01 09:59:20 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!inria!dsouza From: dsouza@inria.fr (Dong-hyun Souza) Newsgroups: comp.dsp Subject: Re: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Aug01.095920.5885@inria.fr> Date: Tue, 01 Aug 1995 09:59:20 GMT References: <1995Jul27.091520.5740@mindspring.com> <1995Jul29.123720.7465@purdue.edu> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: Netscape 1.1N Lines: 9 In article <1995Jul29.123720.7465@purdue.edu>, tkowalski@purdue.edu (Takeshi Kowalski) 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. -- Dong-hyun Souza | dsouza@inria.fr PGP Key fingerprint: B807 B86E 0992 E730 "Keep the channels open."