I don't have the algorithm in front of me, but I don't recall any multiplication, just addition and magnitude comparison. -----Original Message----- From: Jim Lux <[email protected]> Sender: [email protected] Date: Mon, 20 Jun 2011 17:14:44 To: Discussion of precise time and frequency measurement<[email protected]> Reply-To: Discussion of precise time and frequency measurement <[email protected]> Subject: Re: [time-nuts] DDS'ery
On 6/20/11 12:17 PM, [email protected] wrote: > Just a FYI, you don't have to use sine lookup tables. You can generate sine > and cosine on the fly with a coordic. Perhaps not easy at RF speed, but very > common in audio DSP. > It's a tradeoff.. To do CORDIC you need four multiplies and 2 adds, which might be a lot of gates, if you have a fair number of bits, compared to an adder and some lookup tables. If you have a fast multiply instruction on a processor, then CORDIC gets very attractive. The other problem with CORDIC is that roundoff errors accumulate, the longer you run the generator for, because it's basically a difference equation/numerical integration sort of scheme. That said, some of AD's latest DDSes use a monolithic CORDIC generator. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
