Research On High-precision Time Difference Measurement Technology

Electronic war (EW) is the fifth modern warfare in dimension after land, sea, airand space, it plays a decisive role to the victory on the battlefield. The Time Differenceof Arrival (TDOA) location technology is an important content in EW which canmeasure the position of the target in space precisely, will provide not only thenecessary conditions for our equipment deployment, personnel configuration, decisioncontrol and collaborative action, but also a strong guarantee and support for theinterference and attacks to enemy equipment and personnel.There are many factors affecting the TDOA location precision, in which timedifference measurement accuracy is the most critical factor that directly determines thelocation precision. Obviously, the high precision time difference measurementtechnology is a key technology in the military field. Besides, in the civilian field suchas mobile communications, satellite navigation or radar range, time differencemeasurement technology also provide a convenient for people’s life, production andtravel security, which has received extensive attention. Therefore, it is very significantand valuable for us to survey the high precision time difference measurementtechnology.In this paper, the traditional time difference measurement technology usingelectronic counting method is introduced firstly, and several improvement methods areanalyzed in detail. The analysis shows that the electronic counting method could meetan accuracy of ns levels, and the principle is simple, easy to implement, in the situationthat some long baseline positioning or precision requirement is not high which get awide range of applications. Then the traditional cross correlation method and itsimproved algorithm are discussed, and their attainable accuracy of the lower bound aregiven. Also we make a simulation to the measurement precision of the correlationalgorithm with the single frequency carrier signal. At last, the paper studies the twokinds of time difference measurement technology using phase methods. And theirprinciples, time difference estimation algorithm and measurement ambiguity aredeeply discussed. Furthermore, the measurement errors and several main factors thataffect the measurement precision are also simulated and analyzed. The results showthat in high SNR, the phase method and cross correlation function method ofmeasuring time difference technology could achieve the theoretical accuracy of about a few ps to several hundred ps, and can satisfy the present passive localization, mobilecellular communications, satellite navigation and positioning etc requirements, whichare the accuracy of ps level’s high precision time difference measurement method.