Automatic frequency calibration using fuzzy logic controller

摘要

A way of frequency calibration using fuzzy ligic controller (FLC) is presented in this paper. Generally, atomic clocks tend to drift due to temperature, aging, or some environmental effects. It is sure that one cannot compensate for the drift with a fixed amount of control quantity. As a controller, it has the task to adaptively catch up with the variation. Our approach takes advantage of FLC to determine the control quantity. Three procedures are employed in our approach. Firstly the performance of the device being calibrated is observed continuously. Then the FLC uses the performance data to generate the control quantity. Finally the FLC calibrates the device using the computed control quantity. The FLC can calibrate the device at any time since the performance of the device is continuously being monitored. In the experiment, we use FMAS (Frequency Measurement and Analysis System) as the performance evaluation equipment and the FLC is realized by a PC. In the experiment, a cesium-beam oscillator is chosen as the target. The result validates the effectiveness of our approach. An oscillator with frequency offset of -1.4x10~(-13) can be improved to approximately -1.0x10~(-14) after one week of calibration.