Research On The Proximity Fuze System Based On Impulse Mechanism

In recent years, the impulse system of wireless communication has widely caught the attention of experts and scholars, and is gradually applied in various fields, including military, civilian radar, electronic countermeasures, anti-stealth radar, instruments and meters, ultra wideband communications and others. The impulse system communication mode presents a good development trend, with its advantages of high resolution, strong anti-jamming capability, precise positioning, and the simple hardware structure; but it is also faced with the huge technical challenges. Based on the various advantages of impulse mechanism of wireless communication, the thesis presents a design of proximity fuze system based on the impulse mechanism. It mainly contains the design of low voltage UWB pulse source, ultra wideband receiver, and the whole digital logic block.In terms of the low voltage pulse source, this thesis analyzes the working mechanism of the SRD and studies several typical circuit structures. Each circuit is simulated respectively in ADS software, and the effects of various components in the circuits on the result are analyzed. Then the circuit structures are gradually optimized and tested under the guidance of the simulated results. The pulse source circuit has the advantages of simple structure, small volume, low cost, stable performance, etc.In terms of the ultra wideband receiver, this thesis discusses several classical methods of receiving, and then designs the corresponding receiving circuit for the special application fields of proximity fuze. This design uses the latch function of high-speed comparator to latch down the result of comparator who receives the narrow pulse, and the high accuracy time delay device works with the logic control block to lock the high-speed comparator preciesly when pulse echo arrives, realizing the pulse broadening, and digitization at the same time.In terms of the digital logic, coding method is used to improve the anti-interference ability. Eight codes shift out through the shift register to trigger the pulse source to sent narrow pulse, then another shift register shift in the digitized data after the echo arrivals, and then the datas are compared to determine whether to detonate the bomb. The whole digital logic block is implemented in the FPGA, which possess the advantages of high level of integration, short development cycle and stable performance compared to the traditional discrete digital devices. The FPGA chip in the series of CycloneIII from ALTERA corporation is adopted in this design. Firstly, the circuit module is designed in the software QuartusII, then simulated in the software ModelSim, finally downloaded to the FPGA chip to measure.