Research Of Parameter Detecting For Frequency Shift Track Key Signal Based On Time-frequency Analyse

The function of railway is very important in our country's economic development. Security is the lifeline of railage. Track signal detection is one of the most important ways to ensure the safety of the train moving. To guarantee the safety of the train moving on these lines, it is necessary to detect the parameters of the track signals properly, precisely and timely.Based on the characteristics of Domestic frequency shift key track signal, this paper presents a kind of appropriate detection method for our national train signal-----Time-frequency analysis. In such an analysis, Wavelet transformation is a new tool, which can be applied to Time-domain analysis and Frequency-domain Analysis simultaneously. The operation procedure of Wavelet transformation is as follows: drawing out the the useful signal, restraining noise signal, improving signal-to-noise ratio of the system, signal detection is achieved in the noise background. For Instantaneous detection, this paper proposes the way of Hilbert Transform, which focuses on the time-frequency analysis of unstable signal, obtaining instantaneous spectrum of every component, thus computing instantaneous spectrum of domestic frequency shift key track signal. The following detecting methods are presented in this paper:For the narrow band characteristics of the track signal, we use under-rate sampling to reduce the sampling rate, Adopting the way of Wavelet transformation and Hilbert Transform, in different conditions of signal-to-noise ratio, we can detect parameters of domestic frequency shift key track signal, such as Base band modulate frequency, up-Sidebands and down-Sidebands frequency and so on, and the relative errors in such conditions.At last, we give the parameter detecting system based on TMS320VC5402. Experiments shows that it can detect the Base band modulate frequency, signal-to-noise ratio is within 10dB~40dB and the detecting error is within±0.1Hz.