From tkim@berkeley.edu Sat Nov 11 16:19:33 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!berkeley!tkim From: tkim@berkeley.edu (Thiago Kim) Newsgroups: comp.dsp Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Nov11.161933.9200@berkeley.edu> Date: Sat, 11 Nov 1995 16:19:33 GMT Organization: UC Berkeley Department of EECS NNTP-Posting-Host: berkeley.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 10 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. Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm. -- Thiago Kim Tape trading list upon request. SASE required for international mail. From jandersson@pacbell.net Sun Nov 12 00:56:33 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!pacbell!jandersson From: jandersson@pacbell.net (Julien Andersson) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Nov12.005633.3975@pacbell.net> Date: Sun, 12 Nov 1995 00:56:33 GMT References: <1995Nov11.161933.9200@berkeley.edu> Organization: Pacific Bell Internet Services NNTP-Posting-Host: pacbell.net X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Nov11.161933.9200@berkeley.edu>, tkim@berkeley.edu (Thiago Kim) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. -- Julien Andersson Hayes Optima 288 @ 14,400 bps "When every node is whole, the channel opens."