Study On The Test Method Of Virtual Balise

The balise is widely used for train positioning in European Train Control System (ETCS) and Chinese Train Control System (CTCS). In order to improve accuracy of train positioning as well as provide track, location, railway parameters and other important information for train as detailed as possible, the balise have to be mounted on the track in high density, which increases the cost of construction and maintenance greatly. Reducing the operational cost while meeting the positioning accuracy at the same time has practical significance for the development of train control system.The rapid development of Global Navigation Satellite System (GNSS) provides a solution for decreasing the operational cost of train control system. Therefore, the International Union of Railways (UIC) proposed the concept of GNSS-based Virtual Balise. VB is actually a set of on-board equipment. It processes the navigation information of GNSS and generates the message in same format like physical balise, thereby realizes train positioning. The paper designs and implements the architecture of the VB-based onboard equipment. The test platform of VB is built and the comparisons of capture time difference and capture rate between VB and physical balise under different scenarios are carried out in the experiments. The paper has mainly finished the following research work:(1) The overall architecture of VB-based onboard system is designed and realized, which includes positioning unit, safe determination unit and VB unit. The hardware of each functional modules is designed, as well as the software to capture VB and send message.(2) The test platform for VB is constructed, including physical balise, VB and host computer. Physical balise provides the references for VB. According to the communication process of physical balise, the interface protocol of VB is proposed that can send message in the same communication protocol like physical balise. On host computer, VB test software is compiled which can receive the message from both VB and physical balise simultaneously. It can also compare the capture time, display and record the messages.(3) The comparing test between VB and physical balise is conducted. In order to test whether VB can function as a physical balise in practice, the experiment of capturing and sending message of VB and physical balise on the same position is executed. The capturing time difference and capture rate under different scenarios of VB and physical balise are compared to evaluate the performance of VB.The paper tests the capturing time difference and capture rate under different frequencies of GNSS receiver, capture radiuses, velocities. The result shows that VB can send message at the setting position accurately and realize the function as a physical balise.