Two important algorithm of Qualitative Trend Analysis (QTA) for process fault diagnosis was systematically introduced—trend extraction algorithm and trend identification algorithm.

The first section summarizes the background and up-to-date development of Qualitative Trend Analysis(QTA);Then effective methodologies in trend extraction and some major problems in trend identification of Qualitative Trend Analysis(QTA) are proposed.

The principle and application of cyclostationary analysis for demodulation of amplitude modulated signals;

Separating cyclostationary signals from spectrally overlapping interference;

Cyclostationary Characteristic Analysis for Narrowband Signal of Rotation Machinery Fault;