Take the equalizer of cool dog music as an example. The maximum of the first and third equalizers is about 4.00, the maximum of the second equalizer is about 6.00, the minimum of the fourth equalizer is about 4.00, the fifth equalizer is unchanged, the maximum of the sixth equalizer is about 3.00, the maximum of the seventh equalizer is about 2.20, and the maximum of the last two equalizers is about 1.00. Equalizer is a special function to compensate the defects of speakers and sound fields, and to compensate and modify various sound sources by adjusting electrical signals with different frequencies.

Generally speaking, excessive lifting should be avoided, because it may distort the signal. So sometimes it is necessary to improve the high frequency without distorting the signal. We can try to improve the high frequency by attenuating the low frequency.

Introduction of equalizer types

1, frequency domain equalizer

Frequency domain equalizer uses the frequency characteristics of tunable filter to compensate the amplitude-frequency characteristics and group delay characteristics of the actual channel, so that the total frequency characteristics of the whole system including equalizer can meet the transmission conditions without intersymbol interference.

2. Time domain equalizer

The time domain equalizer directly considers the time response, so that the impulse response of the whole transmission system including the equalizer meets the condition of no inter-symbol interference. Frequency domain equalization meets the requirements of Nyquist shaping theorem, and the condition of no intersymbol interference is relatively loose only at the decision point. Therefore, time domain equalizer is widely used in digital communication.