From hpetrov@cam.ac.uk Sun Nov 20 03:00:19 1994 Path: ashpoly!cascade!mxgate!coyoacan!cam!hpetrov From: hpetrov@cam.ac.uk (Hana Petrov) Newsgroups: comp.dsp Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Nov20.030019.1336@cam.ac.uk> Date: Sun, 20 Nov 1994 03:00:19 GMT Organization: University of Cambridge Computer Laboratory NNTP-Posting-Host: cam.ac.uk X-Newsreader: WinVN 0.99.5 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. However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. Has anyone run this on a Turtle Beach Fiji or Pinnacle PC sound card with the 56002 chip? -- Hana Petrov *PLONK* filter active for trolls. NeXTstation Turbo Color - NetBSD 1.0 From dsokolov@mit.edu Mon Nov 21 08:09:19 1994 Path: ashpoly!cascade!brgate!saturno!mit!dsokolov From: dsokolov@mit.edu (Dmitri Sokolov) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Nov21.080919.8217@mit.edu> Date: Mon, 21 Nov 1994 08:09:19 GMT References: <1994Nov20.030019.1336@cam.ac.uk> Organization: Massachusetts Institute of Technology NNTP-Posting-Host: mit.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1994Nov20.030019.1336@cam.ac.uk>, hpetrov@cam.ac.uk (Hana Petrov) 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. -- Dmitri Sokolov "The hatch is open. Is anyone listening?" Sun 3/60 (SunOS 4.1.1) / NEXTSTEP 3.3 From klindqvist@inria.fr Tue Nov 22 05:12:19 1994 Path: ashpoly!cascade!mxgate!coyoacan!inria!klindqvist From: klindqvist@inria.fr (Karen Lindqvist) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Nov22.051219.7417@inria.fr> Date: Tue, 22 Nov 1994 05:12:19 GMT References: <1994Nov20.030019.1336@cam.ac.uk> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: TIN [version 1.2 PL2] Lines: 8 In article <1994Nov20.030019.1336@cam.ac.uk>, hpetrov@cam.ac.uk (Hana Petrov) 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. -- Karen Lindqvist -- INRIA Rocquencourt "In theory there is no difference between theory and practice."