Time-domain signals:
The time domain signal records the waveform information of the signal, including the following parameters:
- amplitude of a signal
- Period of the signal
- frequency of a signal
How are time domain signals tested?
Time Domain Signal UsageoscillographYou can test the amplitude, period, and frequency of the signal.
Difference between time and frequency domains:
As shown in the figure below, the time domain and frequency domain are looking at the same signal from two different angles, and because of the different angles of observation, different test results will be obtained.
Comparison plot of time and frequency domains
For example, when we look at a periodic signal, as shown in the figure below, we can see the waveform of the signal in the upper time-domain measurement plot, while the frequency-domain measurement plot at the bottom shows the distribution of the waveform at different frequencies.
Different results for periodic signals using time and frequency domain tests
Frequency domain signals:
The frequency domain signal records information about the frequency distribution of the signal, including the following parameters:
- Frequency range
- power (output)
- harmonic (wave with frequency an integer multiple of the fundamental)
- clutter
- noises
- disruptions
- (signal) distortion
What equipment is used to test frequency domain signals?
Frequency domain signals can be usedspectrum analyzer,EMI ReceiverFor testing, we offer EMI receivers with built-in spectrum analyzer capabilities.
Modulation signals:
Analog modulated signal spectrum:
Analog modulated signal spectrograms allow you to measure modulation indices and modulation frequencies for AM, FM, PM, etc.
Spectrogram of analog modulated signal
Spectrum of digitally modulated signals:
Digital modulated signal spectrograms measure channel power, adjacent channel power ratio, occupied bandwidth, etc.
Spectrogram of a digitally modulated signal
Noise signal spectrum:
Noise signal spectrogram can measure noise power, noise frequency distribution.
Noise Signal Spectrogram
Distorted signal spectrum:
The distortion signal spectrogram measures harmonic distortion, nonlinear distortion.
Spectrogram of distorted signal