From enovak@rwth-aachen.de Tue Oct 04 11:41:59 1994 Path: ashpoly!cascade!transat!eunet-fr!teletel!rwth-aachen!enovak From: enovak@rwth-aachen.de (Elaine Novak) Newsgroups: comp.dsp Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Oct04.114159.6460@rwth-aachen.de> Date: Tue, 04 Oct 1994 11:41:59 GMT Organization: RWTH Aachen Informatik NNTP-Posting-Host: rwth-aachen.de X-Newsreader: TIN [version 1.2 PL2] 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. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- Elaine Novak US Robotics Courier V.34 @ 9600 Telebit bps "We don't sign stars. We build them." From kstewart@uni-hamburg.de Tue Oct 04 21:34:59 1994 Path: ashpoly!cascade!transat!eunet-fr!teletel!uni-hamburg!kstewart From: kstewart@uni-hamburg.de (Kenji Stewart) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Oct04.213459.4348@uni-hamburg.de> Date: Tue, 04 Oct 1994 21:34:59 GMT References: <1994Oct04.114159.6460@rwth-aachen.de> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: Netscape 1.1N Lines: 9 In article <1994Oct04.114159.6460@rwth-aachen.de>, enovak@rwth-aachen.de (Elaine Novak) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Kenji Stewart "Hardware is temporary. The signal survives." 486DX2/66 (Linux 1.2.13) / NEXTSTEP 3.3