Study On Signal Detection Of Rail Length Measurement Based On Phase-locked Amplifier

We have formally a new high-speed rail era at2010. To2013, high-speedrail speed has reached more than400km/h, up to486.1km/h. Seamless rail is thecornerstone of the high-speed train operation, solder standard rail together, thenlaid on the roadbed. At this time, if the seamless rail size control is not strict, thiswill directly affect the precision of the high-speed railway track. So now alldomestic and foreign manufacturers are trying to develop a standard rail as longas possible, this can reduce the adverse effects of the joint railway.The mainpurpose of this paper is to develop a technique which can measure the length ofrail above100meters.The purpose of the paper is to measure the length of the rail, and measurelength by acoustic wave. Based on the characteristics analysis of the acousticsignal, the paper studied acoustic signal attenuation in the medium. Due to thelength of the measurement, signal amplitude become small among a lot of noise,so it’s a kind of weak signal. The weak acoustic signals detection is the difficultyof the thesis. The paper studied the signal detection technique based onphase-locked amplifier, introduced the principle of the phase-locked amplifier,analyzed the suppression of the noise and designd the signal detection circuit,including acoustic signal generating circuit, pre-filtering links, pre-amplifiercircuit, main amplifier circuit, reference signal generating circuit, referencesignal phase shifting circuit and phase-sensitive detection circuit and so on.Finished the simulation experiment and contrasted the experimental data andtheoretical value. The approach can detect weak signal effectively. Finally, testedthe actual circuit and it’s prove that the technology can achieve signal detectiononce again.Although, the study is focused on the study of long rail measurement, thetechniques can also be applied to other industrial measurement field, such as length cutting and process control and so on. The topic is pratical and innovative,the research is significant. What’more, it can bring huge economic benefits.