Design of Testing System Based on the DRFM

Transcription

1 Applied Mechanics and Materials Online: ISSN: , Vols , pp doi: / Trans Tech Publications, Switzerland Design of Testing System Based on the DRFM Chen Liang 1, Ning Qu 2, Haibo Zhang 2, Xuezhe Tan 2, Hongwen Lin 2 and Tingjun Li 2 1 Information Engineering Institute, Dalian University, Dalian, China Naval Aeronautical and Astronautical University, Yantai, China Litingjun99@126.com Keywords: DRFM; Testing system; Detect Abstract. Based on the disadvantages and problems of current detect ways, come up the testing system which using numerical controlled oscillator (NOC), Digital Radio Frequency Memory (DRFM) and digital down-covert to intermediate frequency (IF) processing, introduce the background information, main functions, total structure and design implementation. Introduction The maintaining of present equipments always has three classes, the third one is to return to the factory. The first class is often field operation. Locate the fault to the LRU through the auto-test BIT inside, and replace the fault element. This is often realized through the inside BIT and the related software. Now the testing of the BIT is still always the qualitative measurement, it is not good at quantitative measurement. The BIT can only test that weather the transmit power is existing which is important to the property of the equipment; for the receiving sensitivity, the testing result is whether the path is working. This paper add some quantitative measurement to the BIT on the grounds of testing system which has the equipments of testing the transmitting power, the receiving sensitivity, and some instruments in order to solve the problem of BIT that can only realize the qualitative measurements. Give out the evaluation of the decrease in property. Main functions and total structure This testing system can fulfill the common test of the equipments on the ground without electric connection with the equipments. This system save the costs and improve the efficiency. The main functions are showed as follows. Simulating the targets: this system can work as the common transponder-handles the receiving signal: delay the time, phase rotation, Doppler modulation, and forwarding. So the system can simulation diverse signal with different distance, different speed, and different reflection area; In-situtesting; Makingtheelectricresume,storethemaintainingprocessandthemaintainingdata. Acquiring,handling,displaying,storeandcopythewavedata; Testingthereceivingsensitivity; Testingthetransmittingpowerandwave; Testingtheequipmentitself. This system is constituted with two parts: the hardware and the software. The total construction of this system is showed in the Fig. 1. All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (ID: , Pennsylvania State University, University Park, USA-09/05/16,00:06:36)

2 Applied Mechanics and Materials Vols Fig. 1 The total construction of this system From the picture we can get that this system is made up of these levels as follows: Hardware level: this hardware level is constituted with microwave module, storing and forwarding module, frequency source, embedded micro-computer, storage system, common extended device port, and the I/O port. Middle level: the middle level isolates the system software with the bottom hardware partly, make the bottom hardware have nothing to do with the driving software. This level initializes some related hardware, the I/O of the data, and the configuration of the hardware. This level has the characters as follows: The relationship of the hardware: as the link between the high-rise software and the hardware, BSP must furnish the detail method to operate and control some hardware because of the characters of facing to the application. The relationship of the operating system: the different operating system has its special hardware port construction because different system has its special software construction. software level: the software level is made up of the OS, document system, GUI, task management and the common modules. Operating system is the base and exploring platform of the application software. The application program base on the operating system is of good portability because the operating system can run in the different micro-computer and furnish the same API ports. The function level: the level is made up of the application program, based on the operating system, which is used to control the related components. It faces the users and the friendly interface is always available for the user. Realizing the design This testing system is a radio frequency forwarder, The receiving frequency is related to the tested equipment s frequency; this system can simulate the target signal. Then this signal is radioing in air and will be regarded as the simulated echo of the tested equipment. This system receives the signal from the tested equipment, converses down to the intermediate frequency. Then acquire the signal by high speed A/D switch in intermediate frequency, delay the time, and rotate the phase. At last converse the signal up to the radio frequency the same as the tested equipment s, and radio in air again. The core of this system is the intermediate processing system, and is also the difficult. The property of the intermediate frequency system affects the precision of the Doppler modulation and the

3 740 Mechanical Engineering, Industrial Electronics and Information Technology Applications in Industry distance simulation, so do the spurious voltage and phase noise of the simulated echo. This system adopts NCO, DRFM, and digital conversing frequency technology; it is of the characters simple structure, elastic control, and convenient debugging. Design of the frequency source The frequency source is used to produce the diverse standard signal and the local oscillation, the frequency point of the local oscillation is controlled by the software. The beginning center frequency is set by the user in the software interface. When it is the auto-testing and the following mode, the local frequency is changing after the entrance frequency in order to adjust to the frequency agility mode. The entrance radio frequency is conversed down to some intermediate frequency and is to be processed. The frequency source system is constituted with the microwave solid component, high precision frequency integration, digital microwave phase-locked loop, high speed digital component, and modular design-these common hardware system designs. The control port adopt the parallel port, the frequency codes are wrote in by the computer through the specialized digital port, which has improve the writing-in speed and the stability; the control software adopts the structure design and the specialized port treaty. It is with the self-checking production, it is expanded and maintainable. Design of the microwave transceiver path The RF signal is conversed down to the intermediate frequency through twice down-conversion, and is with the target Doppler frequency through the intermediate process. Through the digital frequency storage this signal is with some delay time. The delay intermediate signal with the right range changing data is get through the voltage processing circuits. This signal is conversed up twice to the RF signal and then transmitted to the radar. Detect the signal after one down-conversion. The quick frequency measuring circuit will detect the frequency of the entrance signal, test the range of the signal, and the power, period, and the pulse width are get Design the intermediate process The intermediate process is the key technology in this system. This system adopts the advanced NCO, DRFM, and digital conversion. Produce the target echo in digital and make sure that the produced signal is really coherent and low spurious; the users can change the parameter through the computer because of the communication with the embedded control computer in PC-104. All this make the system compact, light, flexible and convenient. The intermediate process of the simulation system is made up of the Fd producer and digital delay lines. The system produces the target parameter, changes the related distance and controls the speed and the intensity. The Fd producer can be realized with the NCO technology, it produces the Doppler signal. The hardware structure of the NCO is mainly the phase accumulator and the sin/cos graph. The phase produced by the accumulator is used as the address to find the sin/cos in the ROM graph, the sin/cos is sent to the multiplier as the digital frequency of the local carrier to realize the frequency mixing. Design the display and control The main control computer controls the functional component properly by the control extension which links the functional component with the main control computer in order to make the simulator work. The control extension adopts the general bus of the control computer-pc104 which is of the characters: high transmit speed, stable property, and good suitability. The main control computer links with the intermediate mode with PC104 bus links with other mode in common I/O ports. This makes the main control computer control the echoes parameter and the frequency of the internal frequency source. So ensure the system more abundant, more flexible, and more reliable. The another function of the control unit is to read the frequency code of the frequency testing mode and produce the control code; at the same time get the pulse width, period and power of the transmitting signal.

4 Applied Mechanics and Materials Vols Conclusions The main control computer links with the intermediate mode with PC104 bus links with other mode in common I/O ports. This makes the main control computer control the echoes parameter and the frequency of the internal frequency source. So ensure the system more abundant, more flexible, and more reliable. The another function of the control unit is to read the frequency code of the frequency testing mode and produce the control code; at the same time get the pulse width, period and power of the transmitting signal. References [1] ZENG Xian-wei, ZHANG Zhi-jun, DING Dong-tao, ZHANG An-xu, LIU Chuan-wu. Calibration Method for Airborne Radar Located on Ground. Modern Radar [J]. 2005:(12):68~70 [2] LI Zong wu. A New Calibration Method for Airborne Radar [J]. Modern Radar[J]. 2001:(2):3~5 [3] XIAO Han-bo. Digital Radio Frequency Memory and Its Application to Radar Echo Simulator [J].Guidance & Fuze. 2002:23(3):25-29 [4] Ma Jian, Ru Wei, Wu Lan, Zhang Zhijun. An Airborne Radar Calibration System Based on Bulk Acoustic Wave Delay Line [J]. Fire Cotrol Radar Tecnology. 2007:36(12):55-58 [5] Li Tingjun, Lin Xueyuan, Research on intergrated navigation system by rubidium clock [J], Journal on Communication 2006, Vols 27(8):pp [6] Li Tingjun, Research on TDOA Passive Tracking Algorithm Using Three Satellites [J]. Journal of Naval Aeronautical and Astronautical University 2009, Vols 24(4):pp [7] Li Tingjun, Lin Xueyuan, GPS/SINS Integrated Navigation System Based on Multi-scale Preprocessing [J], Journal of Wuhan University, 2011, Vols 36(1):pp6-9 [8] Li Tingjun, The Phonetic Complex Data Based on FPGA Key Engineering Materials. Vols 475 (2011)pp

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