From echoi@purdue.edu Sat Aug 10 06:03:28 1996 Path: ashpoly!bigsur!pacrim!krgate!eunha!purdue!echoi From: echoi@purdue.edu (Elaine Choi) Newsgroups: comp.dsp Subject: [INFO] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Aug10.060328.4258@purdue.edu> Date: Sat, 10 Aug 1996 06:03:28 GMT Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 11 Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. 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? -- Elaine Choi "Measuring a record you own is listening, not piracy." Amiga 1200 (Blizzard 030/50) / Linux 1.2.13 From jmoreno@uni-hamburg.de Sun Aug 11 11:09:28 1996 Path: ashpoly!cascade!transat!sunet!nordrelay!uni-hamburg!jmoreno From: jmoreno@uni-hamburg.de (Joachim Moreno) Newsgroups: comp.dsp Subject: Re: [INFO] Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1996Aug11.110928.8138@uni-hamburg.de> Date: Sun, 11 Aug 1996 11:09:28 GMT References: <1996Aug10.060328.4258@purdue.edu> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: Netscape 1.1N Lines: 10 In article <1996Aug10.060328.4258@purdue.edu>, echoi@purdue.edu (Elaine Choi) writes: > Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. > However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Joachim Moreno "The carrier frequency does not drift by accident." Atari Falcon 030 / FreeBSD 2.1