From jweber@stanford.edu Fri Jul 14 15:38:13 1995 Path: ashpoly!cascade!brgate!saturno!stanford!jweber From: jweber@stanford.edu (Jen Weber) Newsgroups: comp.dsp Subject: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jul14.153813.3523@stanford.edu> Date: Fri, 14 Jul 1995 15:38:13 GMT Organization: Stanford University Computer Systems Lab NNTP-Posting-Host: stanford.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 10 Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. 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. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- Jen Weber Tape trading list upon request. SASE required for international mail. From mgarcia@u-tokyo.ac.jp Sun Jul 16 16:06:13 1995 Path: ashpoly!cascade!brgate!saturno!u-tokyo!mgarcia From: mgarcia@u-tokyo.ac.jp (Mike García) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jul16.160613.6031@u-tokyo.ac.jp> Date: Sun, 16 Jul 1995 16:06:13 GMT References: <1995Jul14.153813.3523@stanford.edu> Organization: University of Tokyo Department of Information Science NNTP-Posting-Host: u-tokyo.ac.jp X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Jul14.153813.3523@stanford.edu>, jweber@stanford.edu (Jen Weber) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. > 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. -- Mike García Practical Peripherals 14.4 @ 14,400 bps "There are 14 nodes and only 10 countries. Count again." From smacdonald@purdue.edu Sun Jul 16 23:55:13 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!purdue!smacdonald From: smacdonald@purdue.edu (Steve MacDonald) Newsgroups: comp.dsp Subject: Re: [FLAME] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Jul16.235513.8328@purdue.edu> Date: Sun, 16 Jul 1995 23:55:13 GMT References: <1995Jul14.153813.3523@stanford.edu> <1995Jul16.160613.6031@u-tokyo.ac.jp> Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Jul16.160613.6031@u-tokyo.ac.jp>, mgarcia@u-tokyo.ac.jp (Mike García) writes: > Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Steve MacDonald "Marcus is not one man." Amiga 1200 (Blizzard 030/50) / AmigaOS 3.1