| With the development of wireless communication technology that has played a very important role in the research of wireless data link. The task of this paper is that one ground station locates eight aircrafts. The ground station and aircrafts exchange information via control channels and image channels. The ground station measure range and azimuth of eight aircrafts, together with the height information from aircraft, then further get the location. Information transmission base on the theories of spread spectrum communication. Paper discusses the theory of signal acquisition and tracking. This program choose FFT algorithm as the way to fast signal acquisition, classic Costas loop as carrier wave tracking loop, non-coherent delay-locked loop (DLL) as code tracking loop. The positioning technology of wireless includes two key technology that are ranging and azimuth measurement. Ranging use the way of non-coherent pseudo-random, paper give analysis to its working principle, and what’s more, put theory into practice that platform for that are set up to checking the correctness. Azimuth measurement use the way of interferometer, and discuss its theory and shortage. Long-short base line can figure out the cycle fuzzy of carrier, but not elevation. At last, the shortage are fix up by array antenna consist of two vertical antenna. A platform for measuring the precision of azimuth is built. Its’result achieve the target. The platform for ranging and azimuth measurement is based on FPGA and DSP for base band signal processing. A hardware prototype has developed for ground station base band signal processing, and after testing, it can keep up communication with aircraft. |
