From kjohansson@clari.net Fri Apr 21 02:27:25 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!clari!kjohansson From: kjohansson@clari.net (Kirsty Johansson) Newsgroups: comp.dsp Subject: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Apr21.022725.3308@clari.net> Date: Fri, 21 Apr 1995 02:27:25 GMT Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: NewsWatcher 2.0b24 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? -- Kirsty Johansson *PLONK* filter active for trolls. Atari TT030 - NetBSD 1.0 From kandersson@ox.ac.uk Fri Apr 21 05:58:25 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!ox!kandersson From: kandersson@ox.ac.uk (Karen Andersson) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Apr21.055825.9431@ox.ac.uk> Date: Fri, 21 Apr 1995 05:58:25 GMT References: <1995Apr21.022725.3308@clari.net> Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: Netscape 1.1N Lines: 9 In article <1995Apr21.022725.3308@clari.net>, kjohansson@clari.net (Kirsty Johansson) 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. -- === Karen Andersson === Dept of Electrical Engineering, Oxford University Computing Laboratory "Tape doesn't lie at 02:14. Ears do." From fweber@uu.net Sat Apr 22 07:14:25 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!uu!fweber From: fweber@uu.net (Freya Weber) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Apr22.071425.1085@uu.net> Date: Sat, 22 Apr 1995 07:14:25 GMT References: <1995Apr21.022725.3308@clari.net> <1995Apr21.055825.9431@ox.ac.uk> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: NewsWatcher 2.0b24 Lines: 8 In article <1995Apr21.055825.9431@ox.ac.uk>, kandersson@ox.ac.uk (Karen Andersson) writes: > Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Freya Weber -- UUNET Technologies, Falls Church VA "Row 14. No joke."