On Tuesday 12 July 2005 11:05, Harold D. Skank wrote: >People, > >This questions sounds pretty basic for someone who has been around > SPICE as long as I have. I first ran SPICE when I had to submit > the circuit on punched cards for simulation on an IBM 7074. Had to > wait about a day to get the results back on line printer paper. > Well, on to gEDA questions. > >I have created a state variable BP filter. I can run the ac > analysis using ngspice, and that seems to work very well. It has > allowed me to specifiy the circuit values to get the band shape > that I need. Now though, I would like to see the circuit response > to a 5-cycle truncated sine wave input, since this is the "real" > signal that the filter will see in operation. How do I specify > this as a voltage input and how do I actually run the simulation? > >Sounds dumb, huh? > > Harold Skank
Just off thet op of my head, Harold, a state variable BP filter is usually going to have too high a Q factor to adequately respond to a 5 cycle burst. I think, if I wanted to detect that, I'd time the zero crossings and keep a running average after the first one. From that you can get the reciprocal which is the frequency * 2. If its the right frequency * 2 at the end of the allowed 5 cycle burst time, then its a valid signal. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) 99.35% setiathome rank, not too shabby for a WV hillbilly Yahoo.com and AOL/TW attorneys please note, additions to the above message by Gene Heskett are: Copyright 2005 by Maurice Eugene Heskett, all rights reserved.
