-----Original Message----- From: Tracy Smith To: PICLIST@MITVMA.MIT.EDU Date: Friday, November 12, 1999 11:26 PM Subject: Re: DTMF Tones? [Idea]How to produce sine wave >--- Nikolai Golovchenko wrote: > >> I may be inventing the wheel... Anyway, there was an >> interesting idea in >> Scenix application notes on how to generate sine >> waveform not using table or >> multiply, just addition. Basically, they generate > >It's fun to reinvent the wheel (except when it's on >your nickel). > >> triangle waveform, then >> integrate it and, vou la, something very similar to >> sine is produced. > >Are you sure this is not the Goertzel algorithm? Scott >has a page that discusses this algorithm. Sure it is not. The Goertzel algorithm calculates sine value by a recursive formula, which uses two previous values. Moreover, there is a multiply to do and Scott mentions round off errors accumulation. The method I suggest uses only one previous sample, no multiply, no frequency error, no ... :-) Should Scott Dattalo add yet another, 11th method? > >Also, here's a dtmf generator that uses Goertzel >http://www.ti.com/sc/docs/psheets/abstract/apps/spra066.htm > Are you kidding? This is a decoder algorithm. >http://www.interstice.com/~sdattalo/technical/theory/sinewave.html > >But again, I think Eric Smith's solution is the best. > >> Is this the same as phase accumulators? > >No. Phase accumulators are really, really cool. I just >don't know how to adequately explain them. A quick >alta vista search produced: > >http://www.g4dvj.demon.co.uk/dds.htm > Thanks for the link. Explanation is perfect. I think that my method resembles phase accumulator and table method except there is no table. The table is generated on the run and this is triangle. In my case error of triangle generation is lower, because there is no restriction to use only table values. Finally, this reduced error makes the sine wave frequency more stable. Certainly, the phase accumulator method is more straight-forward and simple, at the cost of frequency jitter. In case of DTMF this is mainly the frequency what matters, because DTMF frequencies are very close. >> P.S. >> Tracy, may I ask you what "dot lo" means? >> >> :-) > >I let that cat out of the bag when I'm ready. :) > >.lo > >===== > >__________________________________________________ >Do You Yahoo!? >Bid and sell for free at http://auctions.yahoo.com > > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -----Original Message----- From: Harold M Hallikainen To: PICLIST@MITVMA.MIT.EDU Date: Saturday, November 13, 1999 1:17 AM Subject: Re: DTMF Tones? [Idea]How to produce sine wave > Of course, a triangle wave is just a square wave run through an >integrator (which is sorta like a 0 Hz low pass filter with a 6 dB/octave >or 20 dB/decade roll-off). I think an additional stage of LPF is cheaper >than doing a D/A of a triangle wave, then filtering it. Thanks Harold, I wonder why it didn't come to my head... In this particular case, triangle of fixed frequency seems easier to produce than square. _ Nikolai Golovchenko, Electrical Engineering Student National Mining University of Ukraine www.nmuu.dp.ua Dnepropetrovsk, Ukraine E-mail: golovchenko@mail.ru