New Digital C-band Pulse Power Meter

Power measurement is the most important and basic part of microwave measurement. With the development of mobile communication and space technology, power measurement is becoming more and more important, and microwave power meter will be smaller, lower cost, wider band, and higher precision. This subject is from one project of Chengdu Sine Science and Technology LTD, and the digital new-type C-band pulse power meter is mainly used to detect the output power of the microwave transmitter.There are a few methods of detecting microwave power. With its high sensitivity, fast response and simple structure, Log-Amp detector has a wonderful future in modern power measurement. This microwave power sensor uses this type of detector.In the design of power meter, power display error is the key specification. The error comes from a lot of sources. The main ones are from temperature change and mismatch between the devices in RF module, and the others should be controlled in some level. In the hardware design, the devices easily influenced by temperature are put in the constant temperature container, and the match between the devices in RF module should be carefully adjusted. In software design, look-up table is used to implement power calibration and frequency compensation. When measuring power, according to the ADC output code from power measurement RF module and the information about pulse carrier frequency from the IFM (Instantaneous Frequency Measurement) module, proper power value is chose in the look-up table, and then is sent to the LED to display. There is some innovation in the system scheme, not only hardware design but also software algorithm, and the final measurement result also proves that this scheme is feasible. Because the power meter is mainly used in special radar system, besides its high precision, it is also required to be small, light and lower cost. The specifications discussed above are met the need by measurement.At the beginning of the thesis, the related concepts about the power measurement and the structure of power meter are introduced, and then what to narrate are such technologies about power measurement as microwave detecting technology, including Log-Amp detecting technology, and Microwave pulse measuring technology. In the third chapter, A/D analogy-to-digital converting technology is mainly presented, for example, the key specifications of ADC and the method about how to choose the suitable ADC, voltage reference and amplifier. Then the error sources in power measurement and the methods about error calibration are discussed. Finally, what to tell is the power meter's scheme evaluating, hardware design, software design, system debugging and the measurement result.