| In recent years, location technology has become a very popular topic in the application of military, for example, there are many ways of testing the performance of artillery shells in weapons proving testing ground. Some of the important parameters of shells through the built-in micro-black box will be recorded. Therefore, only through recovery of missile-borne black box will get some of performance parameters of shells, but it has low efficiency. Because the terrain is relatively complex and most of the current ranges are based on artificial methods to find bomb-fall, like the needle in the haystack, time-consuming effort but with little success. How to improve the efficiency of elastic recovery of missile-borne black box has effect on the development of China's ordnance industry of a new type of ammunition. Hence, the study on the location system of bomb-fall is very necessary, hoping that it can timely and accurately detect its bomb-fall.By use of the fundamental principle of phase difference, the author establishes the positioning model of dual-baseline in this paper. Combined with high frequency electronics and knowledge of radio, the author designs the realization circuit of positioning system, which including RF circuit, mixing circuit, phase discrimination circuit and display circuit. RF circuit used to realize wireless data transmission function of the system, namely through controlling wireless chip by MCU, the low frequency signal will be changed into a high frequency signal, which will be modulated to carrier 433MHz . The modulated signal will be radiated by the antenna as a source. After receiving the signal, the master station will use pre-established sync word in internal register of wireless chip to judge whether the received signal is radiated by the source or not. In practice, we find it is true that conducting phase demodulation in high frequency can detect high frequency signal and microwave signal directly, but due to the high frequency, the error of phase measuring will be great. Therefore, the first two high frequency signals will be transformed into two intermediate frequency signals by mixer circuit, then phase detection. Phase circuit is detected for phase difference of two IF signals. The phase difference is displayed by display circuit. Again by the relationship between azimuth Angle and phase difference; we will finally get the relevant information of transmitting terminal.After the system design is completed, it's necessary to test the hardware and software had done. The test results turn out to be the accessibility of the design. And the corresponding experimental devices built shows that the azimuth error of dual baseline model is smaller than single baseline model and the precision is also higher. This system can realize the judgment of azimuth. It can be with certain application areas and development value. |
