Research on Temperature Control System for High-Performance Oven-Control Crystal Oscillator (OCXO)
|School||Huazhong University of Science and Technology|
|Course||Subtle manufacturing engineering|
|Keywords||OCXO temperature control embedded system cascade control HMI communication protocol|
Timing is a critical part of almost every electronics application. Communication and data transfer generally require a reference signal or source to enable system synchronization and signal generation. As the heart of most reference sources, oven control crystal oscillator (OCXO) is quickly moving to spotlight mainly because its frequency stability has great importance to the whole system. However, variations in temperature can be a major contributor to systematic frequency variation in crystal oscillator. As a consequence, high performance temperature control system is necessarily needed to improve frequency stability.With the view of temperature control knowledge about crystal oscillator and performances of current temperature control system designs, we proposed a novel way based on MSC1210, a technological solutions with conjunction of advanced digital intelligence control technology and traditional practical technology.Secondly, hardware and software of embedded system is designed, include controller and A/D conversion, temperature and measurement and preamplifier, heating, signal digitization, real-time scheduling, and proportion integration differentiation (PID) controller. Cascade control is used to improve the linearity of transistor’s dissipated power heating part.Thirdly, a real-time monitoring human-machine interface (HMI) based on Excel is developed. With this instrument, an optimized process profile such as process parameters and control parameters can be obtained from series of experiments.Fourthly, communication module between host computer and slave computer is brought forward based on open system interconnection (OSI) reference module. Communication protocol software is complied based on the definition of data packet format and data transmission procedure.Finally, we analyzed some specific problems in system debugging and presented seasonable solutions. Experimental data shows this temperature control system has achieved the desire target.