| With the rapid development of mobile communication, people put forward higher and higher requirements on the quality of the network. The fundamental basis to judge network quality is signal strength and its coverage, but there’s still blind spot and weak signal area in wireless communication coverage. Thus, an economical and effective way to solve this problem is to construct a repeater, and as the core component of the fiber optic repeater, the radio frequency optical module has a significant increase on demand. Radio frequency optical module owns many new functions on the basis of the original, such as digital diagnosis function, optical power detection, radio frequency power detection, bias current and so on, which provides an effective means for the performance monitoring, realizing multi-functions in a module and increasing its integration and muti-function, and it also realizes the non-contact automatic detection, making employees more convenient to operate the optical module and reducing the complexity of optical repeaters.On the basis of adequate study of optical modules applied in the fiber optical repeater, this paper summarizes its working principle, analyses the monitoring parameters and function demand of monitoring system, studies the communication protocol and the transparent transmission of the data, and puts forward the general design of monitoring system for the radio frequency optical module with detailed analysis on important parts. In the solution, the monitoring system is divided into two parts, digital diagnostic subsystem and automatic testing subsystem, which are comprised of corresponding hardware and software. Digital diagnostic subsystem uses LPC2134as the control unit of monitoring system which belongs to Philips company chip basing on core of ARM7TDMI-S, and selects the data transmission chip CC1000to realize the modulation and demodulation of the FSK signal, because CC1000can be used to do software programming on the Radio Frequency power, data format and receiving/transmitting model to achieve the FSK communication control; uses asynchronous serial interface to send and receive data; adopts the embedded technology to realize acquisition of digital diagnostic parameters, optical communication among the modules, adjustable optical communication link attenuation and so on; achieves reading, modifying and saving FLASH data under the control of the computer by using the application programming mode. What’s more, in order to suppress noise and other interferences, it adopts the measure of software anti-interference. Automatic testing subsystem uses GPIB interface to build up its hardware, however, in this software, applying the virtual instrument technology develops the electrical parameter test (ATT test, three order inter-modulation test, gain test, bottom noise test, isolation degree test and frequency point test) of optical module and control commands of programmable measuring instruments. In this way, it reduces the testing time and the artificial errors, improves the testing efficiency and makes the complex test process simpler.The testing result of optical module monitoring system shows that the monitoring system runs well, works effectively and meets the performance requirement; meanwhile, it illustrates the feasibility, the advantages and practicality of the design of the system. |
