# RF Wireless World

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## Time domain vs Frequency domain | Difference between time domain and frequency domain

This page on time domain vs frequency domain describes difference between time domain and frequency domain.

There are basically mere representations of various waveforms and parameters in time and frequency domains. These help solve verious complex system related issues such as jitter, phase noise, BER etc.

### Time Domain

The time domain is the domain in which all the signals are represented. Time domain signal can be tested or verified with the use of oscilloscope.

In time domain signals are represented by amplitude on Y axis and time on X axis.

### Frequency Domain

The frequency domain is useful to do more deeper analysis of the time domain signal. Frequency domain helps study frequency contents of the discrete time domain signals as well as continuous time domain signal. The frequency domain signal can be analyzed with the use of spectrum analyzer.

In frequency domain signals are represenred by power(amplitude2) on Y axis and frequency on X axis.

Time domain signal can be converted to Frequency domain signal with the use of Discrete Fourier Transform or Fast Fourier Transform(FFT). Figure-1 depicts representation of various waveforms in time domain and frequency domain. The waveforms include sinewave, triangle, sawtooth, rectangle, pulse etc. As shown sine wave will have single peak at frequency of the sine wave. As we know frequency is the inverse of time period of the sinewave.

There are various measurements performed in time domain and frequency domain to analyze complex baseband signals of various wireless standards such as WLAN, WiMAX, GSM, LTE etc.

Few of the time domain measurements are instantaneous power spectrum, CCDF, eye diagram and more. Few of the frequency domain measurements are power spectrum (frequency vs power diagram), channel frequency response, I/Q constellation digram, EVM etc.

### Time domain vector vs frequency domain vector conversion

Following two methods are very popular for said conversion:
IFFT ➨ Converts Frequency Domain Vector to Time Domain Vector
DFT or FFT ➨ Converts Time Domain Vector to Frequency Domain Vector.
Refer following links on FFT, DFT:
FFT DFT basics with equation➤
16 point FFT implementation basics and MATLAB code➤