Research On Strong Interference Adaptive Cancellation In Shortwave Receiver

Currently, short-wave communications has been widely applied in many military fields,such as warships, etc. With the development of information technology, the demand of communications is also growing, so the ships often have a number of transmitters and receivers. Sometimes when a receiver is working, one or more nearby transmitters also are transmitting high-power signal, as the antenna is omni-directional, some signal from the nearby transmitters can received by the receiver, to the receiver these signal are strong interference, the test results showed that the power of the interference received by the antenna can be up to 10 Walt. It can lead to the receiver obstructed or even damage. Therefore to cancel this strong interference is necessary.In order to solve the above problem and based on the currently available electronic components, this paper presents an adaptive cancellation solution based on digital and analog mixed circuit. Firstly we couple small-signal reference from the transmitting antenna, and sample into the processor, after adjust its amplitude and phase, then convert it to analog signal and amplified, this signal can counteracts with the interference, then the residual signal is used to adjust the weights in the processor, after a period of repetition of the above process, the interference will be adaptively cancelled.According to the above solutions, this paper use Xilinx FPGA development board for the signal processor unit, combined with the use of high speed converter chip ADS822, DAC900, to accomplish the design of the digital sub-board, then complete the FPGA program based on the hardware and adaptive arithmetic. After sum-up, this paper gives some advice and recommendations to the research and realization in the future...