how to create bands based on frequency in matlab ?

I have to create bands based on frequencies. i.e from 0-4Khz one band and the other from 4-8khz. depending on the band i have to cal. the further process.can some one help me on this please

[Walter Roberson]

"bands" do not really have any independent existence. Are you trying to do filtering?

[Carlos]

I agree Walter, it seems he wants to filter. Gokul, you should use a low pass filter for the 0-4Khz band, and a bandpass filter for the 4-8khz band. You can have a look to Matlab´s digital signal design documentation.

[Gokul]

Thank ya'll. yeah i am trying to do filtering, i have to take a speech signal,if it is in speech band ,i have to allow it or else reject it. SPEECH BAND is from 0-kHz and NOISE BAND 4-kHz. Now ,how should i find the frequency at a particular instance of the signal.This is the basic operation of the Voice operated switch. Kindly help and i am beginner of matlab. can some one gimme the coding idea in matlab terminology ?

Answer 1

[Walter Roberson]

I would not necessarily bother with figuring out what the frequency of any group of samples is. I would instead just run it through a 0-4 kHz low-pass filter, and then determine whether the power of the resulting signal matched some threshold, and if so then pass on the signal (either the original signal or the filtered signal as appropriate for the situation.)

[Gokul]

how to use a comb filter ans will this work out the problem