From mlopez@ox.ac.uk Fri May 27 16:50:23 1994 Path: ashpoly!cascade!bigsur!ox!mlopez From: mlopez@ox.ac.uk (Morag López) Newsgroups: comp.dsp Subject: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994May27.165023.6351@ox.ac.uk> Date: Fri, 27 May 1994 16:50:23 GMT Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: WinVN 0.99.5 Lines: 11 Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. 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. Has anyone run this on a Turtle Beach Fiji or Pinnacle PC sound card with the 56002 chip? -- Morag López *PLONK* filter active for trolls. Acorn RiscPC 600 - NetBSD 1.0 From hweber@pacbell.net Fri May 27 21:58:23 1994 Path: ashpoly!bigsur!pacrim!krgate!eunha!pacbell!hweber From: hweber@pacbell.net (Hugo Weber) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994May27.215823.4738@pacbell.net> Date: Fri, 27 May 1994 21:58:23 GMT References: <1994May27.165023.6351@ox.ac.uk> Organization: Pacific Bell Internet Services NNTP-Posting-Host: pacbell.net X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1994May27.165023.6351@ox.ac.uk>, mlopez@ox.ac.uk (Morag López) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Hugo Weber *PLONK* filter active for trolls. 486DX4/100 (FreeBSD 2.0.5) - NetBSD 1.0 From dhernandez@utexas.edu Sat May 28 13:20:23 1994 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!utexas!dhernandez From: dhernandez@utexas.edu (Diego Hernández) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994May28.132023.8010@utexas.edu> Date: Sat, 28 May 1994 13:20:23 GMT References: <1994May27.165023.6351@ox.ac.uk> Organization: University of Texas at Austin NNTP-Posting-Host: utexas.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 11 In article <1994May27.165023.6351@ox.ac.uk>, mlopez@ox.ac.uk (Morag López) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. > 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. If you are posting from AOL, please read RFC 1036 before posting again. -- Diego Hernández Tape trading list upon request. SASE required for international mail. From dsantos@ox.ac.uk Mon May 30 07:33:23 1994 Path: ashpoly!cascade!mxgate!coyoacan!ox!dsantos From: dsantos@ox.ac.uk (Dmitri Santos) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994May30.073323.7480@ox.ac.uk> Date: Mon, 30 May 1994 07:33:23 GMT References: <1994May27.165023.6351@ox.ac.uk> <1994May28.132023.8010@utexas.edu> Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1994May28.132023.8010@utexas.edu>, dhernandez@utexas.edu (Diego Hernández) writes: > Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. > If you are posting from AOL, please read RFC 1036 before posting again. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Dmitri Santos Tape trading list upon request. SASE required for international mail. From jkowalski@pacbell.net Tue May 31 03:22:23 1994 Path: ashpoly!cascade!transat!eunet-fr!teletel!pacbell!jkowalski From: jkowalski@pacbell.net (Joachim Kowalski) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994May31.032223.5448@pacbell.net> Date: Tue, 31 May 1994 03:22:23 GMT References: <1994May27.165023.6351@ox.ac.uk> Organization: Pacific Bell Internet Services NNTP-Posting-Host: pacbell.net X-Newsreader: Netscape 1.1N Lines: 9 In article <1994May27.165023.6351@ox.ac.uk>, mlopez@ox.ac.uk (Morag López) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Joachim Kowalski Practical Peripherals 14.4 @ 28,800 bps "When every node is whole, the channel opens."