From adubois@uu.net Sat Nov 23 00:27:36 1996 Path: ashpoly!cascade!transat!sunet!nordrelay!uu!adubois From: adubois@uu.net (Andrei Dubois) Newsgroups: comp.dsp Subject: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Nov23.002736.3298@uu.net> Date: Sat, 23 Nov 1996 00:27:36 GMT Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: Netscape 1.1N Lines: 10 Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. Source code in 56k assembly uploaded to ftp.ashford-poly.edu:/pub/telecom-archives/dsp56k/stardust_56k.asm. -- Andrei Dubois Tape trading list upon request. SASE required for international mail. From tfournier@inria.fr Mon Nov 25 01:26:36 1996 Path: ashpoly!cascade!mxgate!coyoacan!inria!tfournier From: tfournier@inria.fr (Tobias Fournier) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Nov25.012636.1140@inria.fr> Date: Mon, 25 Nov 1996 01:26:36 GMT References: <1996Nov23.002736.3298@uu.net> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1996Nov23.002736.3298@uu.net>, adubois@uu.net (Andrei Dubois) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Tobias Fournier *PLONK* filter active for trolls. NeXTstation Turbo Color - NetBSD 1.0 From msouza@unam.mx Tue Nov 26 13:03:36 1996 Path: ashpoly!cascade!transat!eunet-fr!teletel!unam!msouza From: msouza@unam.mx (Mei Souza) Newsgroups: comp.dsp Subject: Re: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Nov26.130336.1570@unam.mx> Date: Tue, 26 Nov 1996 13:03:36 GMT References: <1996Nov23.002736.3298@uu.net> Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: Netscape 1.1N Lines: 11 In article <1996Nov23.002736.3298@uu.net>, adubois@uu.net (Andrei Dubois) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. > This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. If you are posting from AOL, please read RFC 1036 before posting again. -- Mei Souza -- Universidad Nacional Autónoma de México (DGSCA) "Do not worship the copy."