#What is a harmonic plus
If we analyze the distortions with total harmonic distortion measurement technique we can know the value of the total harmonic distortion (THD), total harmonic distortion plus noise (THDN), signal to noise and distortion (SINAD), signal to noise ratio (SNR) and nth harmonic value with respect to the fundamental frequency. Because of this, the reference signal may appear in the output at different frequency points. When the input signal is applied to the circuit, due to nonlinear characteristics of the components the distortion may develop in the output signal. In this type, a single frequency sinusoidal signal is applied to the circuit and its output with distortion to be measured and analyzed. The analysis of this distortion is a unique type of analysis. If the signal doesn’t have an equal time period of positive cycle and negative cycle, then such a signal is called asymmetrical signal and even harmonics may appear (multiplies 2nd, 4th, etc of the fundamental frequency) and DC components also may appear in the asymmetrical signals. If the signal having an equal time period of positive cycle and negative cycle, then such a signal is called symmetrical signal & odd harmonics may appear (multiplies 3rd, 5th, etc of the fundamental frequency).
Harmonic-distortion-output-distorted-signal Below two figures indicate the input signal & the distorted output when input is applied to any circuit. Theoretically, the signal includes infinite harmonics. Here, signal X is the reference signal & the signal is showing on CRO have frequencies like 2f, 3f, 4f and so on. When the signal X is displayed on the CRO then the signal X will appear to repeat for every f Hz. For example, X is an input AC signal which has the frequency f Hz. In another way, it can be defined as the ratio between the frequency of the signal and the frequency of the reference signal. Here, harmonic is a type of signal whose frequency is an integral multiple of the reference signal. We can understand the word harmonic like the integer which multiplies fundamental frequencies is known as “Harmonics”.