Time domain measurements Vs Frequency domain measurements - Difference between Time domain measurements and Frequency domain measurements

This page compares Time domain measurements Vs Frequency domain measurements and mentions difference between Time domain measurements and Frequency domain measurements including various parameters and block diagram of measurement setup.

Any real world signal is composed of multiple sine waves of different amplitudes, frequencies and phase angles. The signal can be analyzed in the time domain as well as frequency domain. Some of the parameters of signal such as frequency and phase is difficult to analyze in the time domain and hence they are observed in frequency domain.

The figure-1 depicts time domain and frequency domain measurements. Any signal can be represented in this three domensional axis viz. time, amplitude and frequency. As shown complex waveform can be obtained as sum of multiple sine waves of different amplitude, phase and frequency.

Mathematical Fourier Transform functions such as IFFT and FFT are used to convert frequency domain vector to time domain vector and vice versa.

Time domain Measurements

Figure-2 depicts typical setup used during time domain measurements. As shown Oscilloscope is used as it plots time on X-axis and amplitude of the signal on Y-axis. Following parameters are measured in time domain.
• Inst. power spectrum (Power on Y-axis and Time samples on X-axis).
• CCDF (Complementary Cumulative Distribution Function) used for PAPR analysis.
• Eye Diagram (Real and imaginary signals on Y-axis versus time on X-axis)

Frequency domain Measurements

Figure-3 depicts typical setup used during frequency domain measurements. As shown RF Spectrum Analyzer is used as it plots frequency on X-axis and amplitude or power of the signal on Y-axis. Following parameters are measured in frequency domain.
• Power Spectrum (Frequency on X-axis and Power spectral density on Y-axis)
• Channel frequency response
• EVM
• I/Q constellation Diagram

Following are the links to other useful measurements available on Test and Measurement World website.
Difference between EVM vs subcarriers and EVM vs symbols
Current measurement vs Voltage measurement
Inductance measurement vs Capacitance measurement
Difference between Power and Energy measurements
EMC measurement vs EMI measurement
Electric and Magnetic Field Measurements

What is difference between or comparison between

Following links mention difference or comparison between various equipments:
comparison between VSG and VSA
DIfference between SNA ans VNA
Oscilloscope Bandwidth versus Rise time
Oscilloscope vs Logic Analyzer
Difference between Oscillscope types
Comparison between spectrum and network analyzer