Theroy And Realiztion Of Digital Direction Finding

In the modern electronic warfare system, direction finding technology which can also be called the measure of radiant point angle of arrival is used in the non-fountain orientation for radiant point. By finding the direction of the radiant point, signal deinterleaving parameters can be offered, jamming at the direction and weapon system assistant attack can be led. Also battlers receive intimidate alarm and intimidate direction so that can take tactics and assistance to find the direction of the radiant point.Scope method and phase method are traditional and classic simulating direction finding methods, and that time difference direction finding, doppler direction finding and the complex direction finding of the several methods are new of modern direction finding technology. In several years, along with the development of LSI, high-speed AD/DA and digital signal processing technology. Digital direction finding technology is used in many electronic warfare test equipments and the manufacture of some weapon equips.In this paper, digital direction finding receiver uses double baseline interferometer system to receive signals. signals can be changed into intermediate frequency (IF) baseline by once simulated translater . Then digital sequence of radiant signals can be formed by digital sampling of radiate signals using high-speed ADC. After I—Q translating in FPGA and digital low-pass filtering, signal of radiant point completes direction finding in DSP ASIC. This direction finding uses different algorithms for single signal and double signal. For single signal, AOA of signal is calculated by phase difference which can be obtained through calculating tangent of the I/Q spur track. For double signal, AOA is calculated using con-spectrum correlation phase interferometer method so as to achieve digital direction finding. The direction finding system using above methods is of less equipments and simpler project implementation.