The Research And Development Of Microwave Power Meter Module Based On USB Interface

At present, the domestic power measurement instruments are mostly desktop withcomplex interfaces and big appearance, which are expensive and inconvenient to carry forfield test. While handheld devices usually have a simple function, does not have data analysiscapability of the desktop power analyzer, and is adverse to form a complex measurementsystem. Thus the power measurement instruments with portability and analysis ability andeasy to form complex testing system are demanded more briskly.Through market research and requirements analysis, relying on the subject of researchand development of portable microwave test equipment, as the breakthrough point of RMSpower measurements, microwave power meters based on USB bus is put forward, which arecheap, small size, light appearance, easy to carry and set up a complex test system. Thefunction of the power meter is analyzed, the general design of power meter system isproposed according to the design method of virtual instrument. The entire system consists oftwo parts, one is the host computer software systems, and the other is hardware systems of thepower meter device. The hardware system is mainly responsible for the RF signal processing,signal acquisition and host computer communication. Software system mainly completes theanalysis of the data processing and displaying as well as the calibration of the power andcommunication with the power meter hardware.This paper is focused on the hardware system to expand the research and design.Thehardware system consists of two parts, one is hardware circuits, the other is system softwarefor controlling equipment for data acquisition and data transmission. The50standard SMAhead is used as the input interface for the radio frequency signal, logarithmic detector withdetection of RMS power can be used to detect RMS power. The AVR MCU of ATMELCompany as the main controller of the system, with which the data acquisition and communication with host by USB bus is realized. The Protel99SE are used to designhardware circuit schematics and PCB production. The software system was developed usingC language to write in the AVR Studio4.18of the ATMEL AVR development environment,and the WinAVR compiler is used to complie program, the implementation the programmingon the core chip is used JTAGICE programmer by micro-control electronics development.The software system is debugged by serial port debug assistant and bus monitoringsoftware.The RF signal source and precision multimeter are used to measurement thedetection part, and test results are meet the basic requirements of detecting function; TheBusHound bus monitoring software is used to monitor USB bus, and the results satisfy thetransmission requirements. Finally, the hardware system meets the basic demand of hardwaresystem design.