From ydubois@mindspring.com Mon Aug 08 15:20:37 1994 Path: ashpoly!cascade!transat!ukc!fennimore!mindspring!ydubois From: ydubois@mindspring.com (Yuki Dubois) Newsgroups: comp.dsp Subject: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Aug08.152037.1601@mindspring.com> Date: Mon, 08 Aug 1994 15:20:37 GMT Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.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. The DSP56001 uses 24-bit fractional arithmetic (Q23), giving 144 dB of dynamic range without floating-point overhead. Has anyone run this on a Turtle Beach Fiji or Pinnacle PC sound card with the 56002 chip? -- Yuki Dubois Opinions expressed are solely my own and not those of MindSpring Enterprises. ------------------------------------------------------------ From pkowalski@netcom.com Tue Aug 09 10:39:37 1994 Path: ashpoly!cascade!bigsur!netcom!pkowalski From: pkowalski@netcom.com (Pavel Kowalski) Newsgroups: comp.dsp Subject: Re: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Aug09.103937.2874@netcom.com> Date: Tue, 09 Aug 1994 10:39:37 GMT References: <1994Aug08.152037.1601@mindspring.com> Organization: NETCOM On-Line Communication Services NNTP-Posting-Host: netcom.com X-Newsreader: WinVN 0.99.5 Lines: 8 In article <1994Aug08.152037.1601@mindspring.com>, ydubois@mindspring.com (Yuki Dubois) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Pavel Kowalski -- NETCOM On-Line Communication Services "The carrier frequency does not drift by accident." From hweber@cern.ch Tue Aug 09 21:05:37 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!cern!hweber From: hweber@cern.ch (Heather Weber) Newsgroups: comp.dsp Subject: Re: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Aug09.210537.8326@cern.ch> Date: Tue, 09 Aug 1994 21:05:37 GMT References: <1994Aug08.152037.1601@mindspring.com> <1994Aug09.103937.2874@netcom.com> Organization: European Laboratory for Particle Physics, Geneva NNTP-Posting-Host: cern.ch X-Newsreader: Netscape 1.1N Lines: 9 In article <1994Aug09.103937.2874@netcom.com>, pkowalski@netcom.com (Pavel Kowalski) writes: > Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Heather Weber Opinions expressed are solely my own and not those of European Laboratory for Particle Physics, Geneva. ------------------------------------------------------------ From dito@inria.fr Thu Aug 11 05:07:37 1994 Path: ashpoly!bigsur!pacrim!krgate!eunha!inria!dito From: dito@inria.fr (Dmitri Ito) Newsgroups: comp.dsp Subject: Re: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Aug11.050737.9824@inria.fr> Date: Thu, 11 Aug 1994 05:07:37 GMT References: <1994Aug08.152037.1601@mindspring.com> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: Netscape 1.1N Lines: 10 In article <1994Aug08.152037.1601@mindspring.com>, ydubois@mindspring.com (Yuki Dubois) 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. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Dmitri Ito US Robotics Courier V.34 @ 9600 Telebit bps "The hatch is open. Is anyone listening?"