From hstewart@netcom.com Thu Mar 24 06:57:45 1994 Path: ashpoly!bigsur!pacrim!krgate!eunha!netcom!hstewart From: hstewart@netcom.com (Hana Stewart) Newsgroups: comp.dsp Subject: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Mar24.065745.9784@netcom.com> Date: Thu, 24 Mar 1994 06:57:45 GMT Organization: NETCOM On-Line Communication Services NNTP-Posting-Host: netcom.com X-Newsreader: WinVN 0.99.5 Lines: 10 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. Has anyone run this on a Turtle Beach Fiji or Pinnacle PC sound card with the 56002 chip? -- Hana Stewart -- NETCOM On-Line Communication Services "Tape doesn't lie at 02:14. Ears do." From kstewart@utexas.edu Fri Mar 25 01:07:45 1994 Path: ashpoly!bigsur!pacrim!jpgate!kamome!utexas!kstewart From: kstewart@utexas.edu (Karen Stewart) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Mar25.010745.2521@utexas.edu> Date: Fri, 25 Mar 1994 01:07:45 GMT References: <1994Mar24.065745.9784@netcom.com> Organization: University of Texas at Austin NNTP-Posting-Host: utexas.edu X-Newsreader: Netscape 1.1N Lines: 11 In article <1994Mar24.065745.9784@netcom.com>, hstewart@netcom.com (Hana Stewart) 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. Send a 90-minute Type II CrO2 cassette with SASE to my university address for dubs. -- Karen Stewart Hayes Optima 288 @ 14,400 bps "5 sigma is a discovery. 7 is a question." From neriksson@purdue.edu Fri Mar 25 04:01:45 1994 Path: ashpoly!cascade!bigsur!purdue!neriksson From: neriksson@purdue.edu (Natalia Eriksson) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Mar25.040145.2503@purdue.edu> Date: Fri, 25 Mar 1994 04:01:45 GMT References: <1994Mar24.065745.9784@netcom.com> Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: WinVN 0.99.5 Lines: 8 In article <1994Mar24.065745.9784@netcom.com>, hstewart@netcom.com (Hana Stewart) 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. -- Natalia Eriksson Tape trading list upon request. SASE required for international mail.