Researching On Radio Frequency Identification And Location Of Vehicle In Low SNR

The development of microelectronics and radio frequency (RF) technology promotes the Radio-Frequency identification (RFID). RFID has great advantages in objects tracking, identifying, and supervising. RFID system has been used in many areas and has brought great impact to these areas. RFID has become a heated research topic all over the world. Recently, Dr. Mu Fenghao and others put forward a new system which provides the RFID technique to Intelligent Transportation system to obtain the information from transportation .It is proved to be a good project. The core of the project is the location and identification of the vehicle's Radio-Frequency. The active RFID has been installed in vehicle so that it could transmit the RF signal to mobile base station. The base station estimates the position of the vehicle depending on the received RF signal from RFID in vehicle. However, RF signal sometimes gets weakness because of the distance between car and mobile base station. So it is important to detect the signal and estimate the time delay under low SNR environment.Now, the research of weakness signal detection is always in fixed condition. For example, multi-received antenna; spectrum of magnitude of noise has been known; coherent-match by high sample frequency. These methods get good results, however, are not suitable for the problem in this paper. Researching time-delay of signal with mode known is in condition that Low signal to noise rate (SNR) and low sample frequency.The major work of this paper is1) This paper studies the common algorithms of time delay estimation. According to the characteristics of RF signal, this paper improves the match filter that is used under lower SNR environment.2) In this paper, the Kalman filter is used in time delay estimation. A Kalman filter with vector state-scalar quantity observation is established depending on character of receiving signal, kalman filter can get preciser time delay estimation. Meanwhile, it is a new method to Use the kalman filter to obtain the synchronous carrier waves.3) This paper designs that array antenna to estimate signal angle of arrival(AOA).4) The method is processed simulation experiments. The result indicates that the system can get accurate location under lower SNR by search method.