Development Of Adaptive Control Module For Electrically Tunable Filter

With the rapid development and increasing demand of wireless communication,some wireless communication technologies,such as frequency hopping,spread spectrum technology and dynamic frequency allocation,have gained growing attention.As the key component in frequency hopping communication,high-performance electrically tunable filters are becoming widely applied.However,with the change of experimental environment or the accumulation of working time,the ambient temperature,voltage,current and other parameters will change,which will affect the stability of the wireless communication system.Therefore,a visualized,portable,high-precision and multi-channel adaptive control module for electrically tunable filter is important in application scenarios.An adaptive control module for electrically tunable filter is developed in this thesis,including the development and testing of the electrically tunable filter control module and adaptive module.The indicators of each module are calibrated;and the difficulties and innovations of the adaptive control and adaptive calibration are clarified.By analyzing the basic principle of the varactor diode and electrically tunable filter,this thesis gives a corresponding scheme of controlling the electrically tunable filter based on adjustable voltage.The main contribution of this thesis is the design of an electrically tunable filter control module,which includes the power module,DAC module,ADC module,display module,communication interface,and circuit design of MCU.Compared with the traditional electrically tunable filter control module,the module proposed in this thesis contains a DAC module with 8 channels.The output range can reach 0V?30V and the output precision is up to 16 bits,with 460?V as the minimum output interval.The test results show that the ripple is 20.2 mVp-p.Moreover,an ADC module with 20-bit precision is also designed whose sampling speed reaches up to 2000 times per second with a minimum sampling interval of 3.147?V.Finally,a visualized graphic interface is designed,which is more straightforward than the traditional 8-bit binary codeword control.Based on fitting the discrete data to a continuous curve equation by using four different spatial discrete points curve fitting techniques,a one-to-one correspondence was achieved between continuous input values and continuous output values,which dramatically enhances the tuning capability and tuning accuracy of the electrically tunable filter.Moreover,a closed-loop control system is propose,which realizes temperature drift adaptive compensation and frequency offset adaptive compensation.This happens by feeding back the temperature parameters and the center frequency of the electrically tunable filter into the system through both hardware circuits and software algorithms.The average frequency offset adaptive compensation frequency offset error can reach 1MHz in this test.Finally,the cascading tests on the overall scheme is conducted.I will recap this research and give some suggestions on future work.