The Design Of The Portable Rail Signal Sending Device

ABSTRACT:The speed of trains has become gradually fast. Especially the speed of high-speed railway has reached the world advanced level. The rapid development of railway causes that the entire system has high requirements for locomotive signal. The locomotive signal devices are a very important part of automotive systems that their working state directly affects the safe operation of trains and traffic efficiency. So it is very necessary to detect the cab signal when the locomotive pulls in and out the depot.The track circuit is an important part of the railway system. The track circuit and turnouts with switch machines collectively referred to outdoor big three. Its main work is to judge the occupancy of track and use the frequency shift signal to transmit the running information. And it is a composite of the block. The detection of locomotive signal devices is that use the signal generating device to send the simulate frequency shift signal in orbit and detect the reception and feedback of the locomotive signal equipment.At present, the detection of locomotive signal is to use mainly the link code box to sent signal in the locomotive depot by the section of electricity locomotive signal maintenance. Testing personnel on-site boarded the train to check manually code. The detection has heavy workloads and it is easy to leak or makes errors. The main work of this thesis is targeted at the locomotive signal detection and combines with the existing shortcomings for complicated operation, single function, not easy to equip at the scene detection to propose a kind of point that design a portable railway signal generator based on the embedded system and the advanced DDS (Direct Digital Synthesis). The generator sends frequency shift signal or FSK signal with high precision, stable performance, at the same time as the railway site frequently out of the station, on-site staff burden is heavy, the generator has the advantages of simple operation, convenient carrying, so it reduces the labor intensity of workers. This thesis mainly includes the following contents:(1)Analyses the characteristics of the existing track circuit information to propose the system design method include in the generator function and technique index.(2)Introduce the embedded technology.DDS technology and the principle of DDS.(3)Draw the hardware circuit design and PCB of the railway signal generator. Present the realization method of frequency shift signal by DDS. The hardware structure of the railway signal generator is divided into two parts:The system control part and the output signal code part. The system control part selects STM32F103VET6as the core chip because of its high performance, low cost, power consumption and the Cortex-M3.The output signal code part controls the entire system, because that the signal phase of the railway frequency shift signal has been continuously, and the performance is stable, can adapt to the harsh environment of railway industry therefore, through the different methods of selection, finally we use the advanced DDS technology, the core chip is AD9854chip.(4) Introduces the software realization process. This paper gives the program flow chart, and compares the two signal generating method:DAC technology and DDS technology. DAC technology is the internal module that it is contained by the STM32F103VET6chip, the direct program can control the chip signal. The STM32chip needs to control DDS chip. Through the comparison of the performance of the output signal and the method of generating FSK signal, finally we select the DDS technology.Finally, obtain the two kinds of experimental data and analyses the different phenomena and suggest the need for improved deficiencies and make a comprehensive summary of the design.