| Frequency hopping communication is a means of spread spectrum communication. Because of its high anti-jamming capability, low intercept probability, easily making a network by code division multiple access technology, etc., Frequency Hopping (FH) communication system has been widely used in many areas.Electronic reconnaissance is a prerequisite and basis of electronic antagonism. An effective reconnaissance technology is the primary indemnification to interfere enemy communications. The primary mission of electronic reconnaissance includes reception, direction finding and localization. With retainng the time domain, frequency domain and the airspace all the information, array signal processing has been widely used in electronic reconnaissance system. It is significant for enhancing the anti-jamming capacity of electronic warfare to combine characteristics of array signal processing and frequency hopping and research effective frequency hopping reconnaissance means.This paper has designed the direction finding solution based on wideband digital channelized receiving, and completed the FPGA implementation of the relevant digital signal processing algorithms. The main content of this paper are presented as follows:Firstly, the basic principle of frequency hopping communication is introduced. Making the Joint Tactical Information Distribution System (JTIDS) as the reference object, the solution of wideband digital channelized receiving for frequency hopping is designed.The FPGA implementation of the digital channelized algorithm and the unitary MUSIC (Multiple Signal Classification) algorithm are described in detail. In the digital channelized design, it divides the 48MHz-wide frequency band into 16 subchannels. For 8 array elements uniform linear array, the unitary MUSIC design uses the Jacobi method to compute eigenvalue decomposition.Finally, all DSP functions in FPGA are computed by only fixed-point operation with finite bit-length, and practically tested in Virtex-4SX55 FPGA. |
