high level DSP FFT question

[robismyname]

Getting more involved with DSP. Before I start buying books and development kits I would like to know a bit more about FFT. Basically what I would like to know is if FFT did not exist what would we not be able to do in DSP? In other words what is the benefit of FFT? and compared to regular FT?

And lastly FT is just converting a time signal into the frequency domain, correct? So my question is, is a spectrum analyzer a time domain to frequency converter? Does a SA do FFT or just FT?

ANy help is appreciated.

 

[gongdori]

I am no DSP expert, but as far as I know there was DFT before FFT. DFT takes much longer time than FFT.
Spec an is a time domain to frequency domain converter and I am pretty sure it uses FFT internally because fast conversion is required.

 

[rohitkhanna]

FFT is the same as FT, except that it does the conversion "faster". Thats what the 1st 'F' stands for

 

[robismyname]

FFT is the same as FT, except that it does the conversion "faster". Thats what the 1st 'F' stands for

I knew that but can you explain applications in DSP that require FFT and some applications that dont require FFT? Since FT is just converting a time signal to the frequency domain why would a dsp need to do this?

 

[zoulzubazz]

looks like you have to a long way to go matey, fast fourier transform (FFT) is an efficient way of performing fourier transform, it is more computationally efficient than doing it using traditional FT. since DSP's have memory limits computationally efficient methods are evidently faster than computationally intense ones(since it would require more storage to store results).the link describes fft in some detail:

https://www.ni.com/white-paper/4278/en

 

[pstuckey]

And lastly FT is just converting a time signal into the frequency domain, correct? So my question is, is a spectrum analyzer a time domain to frequency converter? Does a SA do FFT or just FT?

Newer spectrum analyzers do use FFT. Older ones were a swept tuner with narrowband filtering which then fed a power detector.

 

[milind.a.kulkarni]

The FFT or DFT is lagerly used in the singal analysis.....for an example - let say one want to do the tone analysis of the speech signal or if you want to remove the noise from signal etc.....

Good Luck