Digital Signal Processing

Question

I started my thesis project for college, I have little experience in the area of digital signal processing, but enough to start a project; I have a question I could not answer.

How to read the magnitude of a Fourier transform, when using the Fourier transform, to calculate the magnitude of the imaginary and real parts, not achievement convert data to dB?

if there is any reference to this article serious issue of great help if you can share.

The FFT libraries I'm using are these:

Frequency Bin Example

michaelkellett · Accepted Answer

dB is a ratiometric measurement:

If we take the reference amplitude to be r then the amplitude of a signal v in dB is:

dBv = 10*log(v/r)

When we are talking about electrical signal we are usually much more interested in power ratios so dBp = 20*log(v/r)

The v and p are not usually written down.

So if we have a signal of amplitude 2V and noise of 8mV the signal to noise ratio would normally be expressed as 20*log(2/.008) = 47.95dB

There is a reasonable Wiki article: https://en.wikipedia.org/wiki/Decibel

MK

clem57 · Answer

http://stackoverflow.com/questions/6393257/getting-fourier-transform-from-phase-and-magnitude-matlab has example of the magnitude of both parts. C

michaelkellett · Answer

Do you have access to MATLAB - (there are home and student versions at reasonable prices and if you are at college they may have licenses you can use).

MATLAB is a really great way to play with Fourier transforms and signal processing maths in general. The built in help is as good as most text books and it is really easy to try things.

I develop almost all of my signal processing stuff for processors or FPGA by starting out by modelling the process in MATLAB.

MK

Digital Signal Processing

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