Hi all, What is the significance of complex FIR filters used? In general the inputs are the sequences of real values, then where can the complex filters be used? If they are used for real inputs, then how do we interpret the complex outputs? Regards, Ishtiaq.

# Complex filters

Started by ●February 23, 2004

Reply by ●February 23, 20042004-02-23

"I. R. Khan" wrote:> > Hi all, > > What is the significance of complex FIR filters used? In general the inputs > are the sequences of real values, then where can the complex filters be > used? > > If they are used for real inputs, then how do we interpret the complex > outputs?The most obvious one I can think of is an FIR filter which implements the Hilbert transformer which by definition has a complex valued output. Erik -- +-----------------------------------------------------------+ Erik de Castro Lopo nospam@mega-nerd.com (Yes it's valid) +-----------------------------------------------------------+ "I think there is a world market for maybe five computers." -- Thomas Watson, Chairman of IBM, 1943

Reply by ●February 23, 20042004-02-23

"I. R. Khan" wrote:> Hi all, > > What is the significance of complex FIR filters used? In general the inputs > are the sequences of real values, then where can the complex filters be > used? > > If they are used for real inputs, then how do we interpret the complex > outputs?Complex filters usually needed when down conversion is used, for example, in the software radio. Then the real signal is multiplied to the complex sine wave and then filtered by sharp complex low pass filter. And here at the output the positive and negative frequencies occur. A.Ser.

Reply by ●February 23, 20042004-02-23

"I. R. Khan" <ir_khan@hotmail.com> wrote in message news:c1ceoq$1gtpmo$1@ID-198607.news.uni-berlin.de...> Hi all, > > What is the significance of complex FIR filters used? In general theinputs> are the sequences of real values, then where can the complex filters be > used? > > If they are used for real inputs, then how do we interpret the complex > outputs? > > Regards, > Ishtiaq.Use Google groups search to look up a thread on this topic - we had a fairly long discussion less than a month back. Cheers Bhaskar