闡述了軌道交通列車定位技術。介紹了在軌道交通系統中列車定位技術的功能，國內外軌道交通中主要采用的列車定位方法，重點論述了幾種主要定位技術，并從定位精度、閉塞制式、維護投資成本、抗干擾等方面進行分析比較。提出目前軌道交通定位技術應綜合運用，取長補短，多種方法相互融合，才能滿足軌道交通中對安全可靠性的要求。
Abstract:
Rail train positioning technology is described. The paper introduces the funetions of the train positioning technology in the rail transit system， the main methods of train positioning do mestic and international rail， and focuses on several key methods， analyzes and compares from the positioning accuracy， block system, maintenance and investment cost， interference and so on， suggested that the current rail positioning technology should be integrated use of positioning method of meriging， learn from each other， to meet the reliability requirements of rail safety.
同步技術是跳頻通信系統的關鍵技術之一，尤其是在快速跳頻通信系統中，常規跳頻通信通過同步字頭攜帶相關碼的方法來實現同步，但對于快跳頻來說，由于是一跳或者多跳傳輸一個調制符號，難以攜帶相關碼。對此引入雙跳頻圖案方法，提出了一種適用于快速跳頻通信系統的同步方案。采用短碼攜帶同步信息，克服了快速跳頻難以攜帶相關碼的困難。分析了同步性能，仿真結果表明該方案同步時間短、虛警概率低、捕獲概率高，同步性能可靠。
Abstract:
Synchronization is one of the key techniques to frequency-hopping communication system， especially in the fast frequency hopping communication system. In conventional frequency hopping communication systems， synchronization can be achieved by synchronization-head which can be used to carry the synchronization information， but for the fast frequency hopping， Because modulation symbol is transmitted by per hop or multi-hop， it is difficult to carry the correlation code. For the limitation of fast frequency hopping in carrying correlation code， a fast frequency-hopping synchronization scheme with two hopping patterns is proposed. The synchronization information is carried by short code， which overcomes the difficulty of correlation code transmission in fast frequency-hopping. The performance of the scheme is analyzed， and simulation results show that the scheme has the advantages of shorter synchronization time， lower probability of false alarm， higher probability of capture and more reliable of synchronization.
