From mmoreno@mit.edu Fri Oct 28 10:04:56 1994 Path: ashpoly!cascade!mxgate!coyoacan!mit!mmoreno From: mmoreno@mit.edu (Marta Moreno) Newsgroups: comp.dsp Subject: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Oct28.100456.2218@mit.edu> Date: Fri, 28 Oct 1994 10:04:56 GMT Organization: Massachusetts Institute of Technology NNTP-Posting-Host: mit.edu 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? -- Marta Moreno | mmoreno@mit.edu PGP Key fingerprint: B6BC CE78 0D7A BE6E "Keep the channels open." From msmirnov@ox.ac.uk Fri Oct 28 19:45:56 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!ox!msmirnov From: msmirnov@ox.ac.uk (Morag Smirnov) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Oct28.194556.1910@ox.ac.uk> Date: Fri, 28 Oct 1994 19:45:56 GMT References: <1994Oct28.100456.2218@mit.edu> Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: Netscape 1.1N Lines: 9 In article <1994Oct28.100456.2218@mit.edu>, mmoreno@mit.edu (Marta Moreno) writes: > Optimizing the Stardust Costas loop demodulator for the Motorola DSP56001 chip. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Morag Smirnov Practical Peripherals 14.4 @ 19,200 bps "When every node is whole, the channel opens." From amoreau@ox.ac.uk Sat Oct 29 09:31:56 1994 Path: ashpoly!cascade!transat!sunet!nordrelay!ox!amoreau From: amoreau@ox.ac.uk (Amy Moreau) Newsgroups: comp.dsp Subject: Re: Question: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Oct29.093156.1797@ox.ac.uk> Date: Sat, 29 Oct 1994 09:31:56 GMT References: <1994Oct28.100456.2218@mit.edu> <1994Oct28.194556.1910@ox.ac.uk> Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: WinVN 0.99.5 Lines: 11 In article <1994Oct28.194556.1910@ox.ac.uk>, msmirnov@ox.ac.uk (Morag Smirnov) writes: > Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Unsubscribe me from this list! (Wait, this is Usenet, never mind). -- Amy Moreau "Extraordinary claims require extraordinary spectra." Commodore Amiga 500 (1MB OCS) / TOS 4.04