From lkuznetsov@illinois.edu Sun Jul 24 23:59:25 1994 Path: ashpoly!cascade!bigsur!illinois!lkuznetsov From: lkuznetsov@illinois.edu (Lars Kuznetsov) Newsgroups: comp.dsp Subject: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Jul24.235925.5099@illinois.edu> Date: Sun, 24 Jul 1994 23:59:25 GMT Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: TIN [version 1.2 PL2] 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. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- Lars Kuznetsov SupraFAXModem 28.8 @ 33,600 bps "Do not worship the copy." From avasiliev@uu.net Tue Jul 26 23:44:25 1994 Path: ashpoly!cascade!transat!ukc!fennimore!uu!avasiliev From: avasiliev@uu.net (Anja Vasiliev) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Jul26.234425.7540@uu.net> Date: Tue, 26 Jul 1994 23:44:25 GMT References: <1994Jul24.235925.5099@illinois.edu> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: Netscape 1.1N Lines: 9 In article <1994Jul24.235925.5099@illinois.edu>, lkuznetsov@illinois.edu (Lars Kuznetsov) 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. -- Anja Vasiliev | avasiliev@uu.net PGP Key fingerprint: 1448 14D6 A0F7 04C1 "Keep the channels open." From kandersson@titech.ac.jp Thu Jul 28 20:28:25 1994 Path: ashpoly!cascade!transat!ukc!fennimore!titech!kandersson From: kandersson@titech.ac.jp (Katrin Andersson) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Jul28.202825.9699@titech.ac.jp> Date: Thu, 28 Jul 1994 20:28:25 GMT References: <1994Jul24.235925.5099@illinois.edu> <1994Jul26.234425.7540@uu.net> Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1994Jul26.234425.7540@uu.net>, avasiliev@uu.net (Anja Vasiliev) 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. -- Katrin Andersson SupraFAXModem 28.8 @ 19,200 bps "Tape doesn't lie at 02:14. Ears do." From hchoi@mit.edu Sat Jul 30 18:16:25 1994 Path: ashpoly!cascade!transat!ukc!fennimore!mit!hchoi From: hchoi@mit.edu (Hugo Choi) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Jul30.181625.5556@mit.edu> Date: Sat, 30 Jul 1994 18:16:25 GMT References: <1994Jul24.235925.5099@illinois.edu> <1994Jul26.234425.7540@uu.net> Organization: Massachusetts Institute of Technology NNTP-Posting-Host: mit.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 8 In article <1994Jul26.234425.7540@uu.net>, avasiliev@uu.net (Anja Vasiliev) writes: > Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. -- Hugo Choi Tape trading list upon request. SASE required for international mail. From alaurent@earthlink.net Mon Aug 01 20:44:25 1994 Path: ashpoly!cascade!transat!eunet-fr!teletel!earthlink!alaurent From: alaurent@earthlink.net (Andrei Laurent) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Aug01.204425.8027@earthlink.net> Date: Mon, 01 Aug 1994 20:44:25 GMT References: <1994Jul24.235925.5099@illinois.edu> <1994Jul26.234425.7540@uu.net> <1994Jul30.181625.5556@mit.edu> Organization: EarthLink Network NNTP-Posting-Host: earthlink.net X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1994Jul30.181625.5556@mit.edu>, hchoi@mit.edu (Hugo Choi) writes: > Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Andrei Laurent Opinions expressed are solely my own and not those of EarthLink Network. ------------------------------------------------------------