Studiy On Automatic Identification And Demodulator Algorithm Of Cab Signal

The development of cab signal has experienced a long period of time in our country. The biggest difficult that it met with was there were many automatic blocking track circuit systems. At present, there are polarized frequency signal and alternated counting signal and national made frequency signal and UM71 and also ZPW2000 signal in our nation's railway application. And all these signals were classified to be uplinks and downlinks. The inconsistent systems brought certain difficulties to the detection of cab signals, but the current cab signal equipments all needs labor participation. Therefore, it is significant to design a kind of equipment which can automatically identify and demodulate all kinds of cab signals.This thesis first analyzed the characteristics of the current cab signals existed in our national railway systems, based on which we proposed a kind of cab system scheme which can automatically identify and demodulate all kinds of cab signals. From the point of engineering practicability, this scheme gave automatic identification and demodulation algorithm theory and the simulating realization of these algorithms. Aimed at the polarized frequency signal, the thesis proposed a time domain demodulation algorithm; aimed at the alternated counting signals, the thesis proposed a demodulation method which combined both time domain and frequency domain; aimed at the frequency shift signals, the thesis proposed a bandpass sampling-based demodulation algorithm taking engineering practicability into account. Simulation experiments were carried out, and the results of these experiments showed that this algorithm can automatically identify and demodulating cab signals, and this algorithm has the advantages of high executing speed and high demodulation solutions.