From tramirez@uni-hamburg.de Tue Sep 24 04:37:03 1996 Path: ashpoly!cascade!bigsur!uni-hamburg!tramirez From: tramirez@uni-hamburg.de (Takeshi Ramírez) Newsgroups: comp.dsp Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Sep24.043703.1088@uni-hamburg.de> Date: Tue, 24 Sep 1996 04:37:03 GMT Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: Netscape 1.1N 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. Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm. -- Takeshi Ramírez US Robotics Courier V.34 @ 9600 Telebit bps "There are 14 nodes and only 10 countries. Count again." From neriksson@illinois.edu Wed Sep 25 08:08:03 1996 Path: ashpoly!cascade!bigsur!illinois!neriksson From: neriksson@illinois.edu (Nadia Eriksson) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Sep25.080803.5482@illinois.edu> Date: Wed, 25 Sep 1996 08:08:03 GMT References: <1996Sep24.043703.1088@uni-hamburg.de> Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1996Sep24.043703.1088@uni-hamburg.de>, tramirez@uni-hamburg.de (Takeshi Ramírez) writes: > 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. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Nadia Eriksson *PLONK* filter active for trolls. Atari TT030 - NetBSD 1.0