From fsouza@panix.com Thu Mar 02 13:19:06 1995 Path: ashpoly!cascade!mxgate!coyoacan!panix!fsouza From: fsouza@panix.com (Fiona Souza) Newsgroups: comp.dsp Subject: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar02.131906.8281@panix.com> Date: Thu, 02 Mar 1995 13:19:06 GMT Organization: Public Access Unix of New York NNTP-Posting-Host: panix.com X-Newsreader: TIN [version 1.2 PL2] Lines: 11 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. 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. -- Fiona Souza | fsouza@panix.com PGP Key fingerprint: 2727 A90D 8D5B F82E "Keep the channels open." From mmoreau@inria.fr Fri Mar 03 08:05:06 1995 Path: ashpoly!cascade!bigsur!inria!mmoreau From: mmoreau@inria.fr (Morag Moreau) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar03.080506.5743@inria.fr> Date: Fri, 03 Mar 1995 08:05:06 GMT References: <1995Mar02.131906.8281@panix.com> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Mar02.131906.8281@panix.com>, fsouza@panix.com (Fiona Souza) writes: > 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. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. -- === Morag Moreau === Dept of Electrical Engineering, INRIA Rocquencourt "5 sigma is a discovery. 7 is a question." From kkuznetsov@netcom.com Sat Mar 04 04:00:06 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!netcom!kkuznetsov From: kkuznetsov@netcom.com (Karen Kuznetsov) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar04.040006.4279@netcom.com> Date: Sat, 04 Mar 1995 04:00:06 GMT References: <1995Mar02.131906.8281@panix.com> <1995Mar03.080506.5743@inria.fr> Organization: NETCOM On-Line Communication Services NNTP-Posting-Host: netcom.com X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1995Mar03.080506.5743@inria.fr>, mmoreau@inria.fr (Morag Moreau) writes: > Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Karen Kuznetsov | kkuznetsov@netcom.com PGP Key fingerprint: CA78 07EB FFD4 5336 "Keep the channels open." From rmoreau@uu.net Sat Mar 04 08:31:06 1995 Path: ashpoly!cascade!mxgate!coyoacan!uu!rmoreau From: rmoreau@uu.net (Raj Moreau) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar04.083106.6611@uu.net> Date: Sat, 04 Mar 1995 08:31:06 GMT References: <1995Mar02.131906.8281@panix.com> <1995Mar03.080506.5743@inria.fr> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Mar03.080506.5743@inria.fr>, mmoreau@inria.fr (Morag Moreau) writes: > Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Raj Moreau Opinions expressed are solely my own and not those of UUNET Technologies, Falls Church VA. ------------------------------------------------------------ From mkuznetsov@cern.ch Sun Mar 05 21:30:06 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!cern!mkuznetsov From: mkuznetsov@cern.ch (Min-jun Kuznetsov) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Mar05.213006.9807@cern.ch> Date: Sun, 05 Mar 1995 21:30:06 GMT References: <1995Mar02.131906.8281@panix.com> <1995Mar03.080506.5743@inria.fr> Organization: European Laboratory for Particle Physics, Geneva NNTP-Posting-Host: cern.ch X-Newsreader: TIN [version 1.2 PL2] Lines: 11 In article <1995Mar03.080506.5743@inria.fr>, mmoreau@inria.fr (Morag Moreau) writes: > Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Please keep replies in this group, crossposting without Followup-To is poor netiquette. -- Min-jun Kuznetsov US Robotics Courier V.34 @ 33,600 bps "Measuring a record you own is listening, not piracy."