Adaptive equalization method and adaptive equalizer

An adaptive equalizer, comprising:

• a filter, configured to filter input signals according to a first filter coefficient to obtain a first filtered signal, and further configured to filter the input signals according to a second filter coefficient to obtain a second filtered signal;
• a coefficient updating unit, configured to buffer the input signals to obtain buffer signals, and further configured to obtain an update magnitude of the filter coefficient according to a level (n−1) error signal and the buffer signals, and obtain the second filter coefficient according to the update magnitude, wherein n is a positive integer greater than 1;
• a standard decider, configured to decide the first filtered signal based on an original constellation map to obtain a first decision signal, and further configured to decide the second filtered signal based on the original constellation map to obtain a second decision signal;
• a level decider, configured to decide the first filtered signal based on a level (n−1) constellation map to obtain a level (n−1) pseudo decision signal, and further configured to switch the level (n−1) constellation map to a level n constellation map if average energy of the level (n−1) error signal is less than a level (n−1) threshold, wherein the level n constellation map is the original constellation map;
• and
• a comparator, configured to compare the level (n−1) pseudo decision signal with the first filtered signal to obtain the level (n−1) error signal;
• wherein the level decider comprises:
• a first level switching unit, configured to receive the first filtered signal and connect a level (n−1) decision mapper, and further configured to switch from connecting the level (n−1) decision mapper to connecting a level n decision mapper when a level switching signal instructs switching;
• the level (n−1) decision mapper, wherein the level (n−1) constellation map is located in the level (n−1) decision mapper, and the level (n−1) decision mapper is configured to decide the first filtered signal based on the level (n−1) constellation map to obtain the level (n−1) pseudo decision signal;
• the level n decision mapper, wherein the level n constellation map is located in the level n decision mapper, and the level n constellation map is the original constellation map;
• a monitoring unit, configured to instruct switching by the level switching signal if the average energy of the level (n−1) error signal is less than the level (n−1) threshold;
• and
• a second level switching unit, configured to connect the level (n−1) decision mapper and output the level (n−1) pseudo decision signal, and further configured to switch from connecting the level (n−1) decision mapper to connecting the level n decision mapper when the level switching signal instructs switching.