APPLICATIONS OF MATLAB IN SCIENCE AND ENGINEERING - PART 7

Thiết kế bộ lọc và cửa sổ hộp thoại công cụ phân tích Các ứng dụng của MATLAB Khoa học và Kỹ thuật Đồng bộ hóa đầu vào phục hồi của hệ thống này là đồng bộ hóa lọc, sản lượng của nó được quan trọng nhất bốn bit của | Design Methodology with System Generator in Simulink of a FHSS Transceiver on FPGA 307 Coefficients _HPF Coefficients _BPF Fig. 23. Splitting filters block diagram a b c Fig. 24. Splitting filters signals a input b FHSS filtered c synchronization filtered Fig. 25. Filter Design and Analysis Tool dialog window 308 Applications of MATLAB in Science and Engineering Synchronization recovery The input of this system is the synchronization filtered in its output gets the most significant four bits of the pseudorandom code Fig. 26 . It is formed Fig. 27 by a 9 MHz recover a synchronous demodulator a load and enable generators and a Linear Feedback Shift Register code generator. a -05 16 p b 12 0 1f 1 I 1 . .1-1-1-1-1-1-1--1--1--1- -M I lilll RiBIIIWiliW l Br -L Ị J. 1 -L 1 -L I J-_Ị -1 - _ _I-I---I-I-- _ __I_j 05 1 1S 2 25 3 35 5_5 ----- __77- 05 1 15 2 3 35 5 5 I 10 16 2 22 23 2. 25 I 1-5 16 2 22 23 2. 25 I 1-5 Fig. 26. Synchronization recovery signals a synchronization filtered b code recovered ENABLE GENERATOR Fig. 27. Synchronization recovery block diagram Carrier recover 9 MHz This system recovers the carrier of the synchronization signal Fig. 28 . Initially the phase-modulated signal is squared and filtered to get double the carrier frequency with an 18 MHz band pass filter Fig. 29 the sample frequency is 180 MHz. The 18 MHz signal is squared by a comparator and a pulse is generated with each rising edge. Finally an accumulator generates a 9 MHz squared signal with 50 duty cycle. FDATool_BPF Fig. 28. Carrier recovery of 9 MHz block diagram Synchronous demodulator The block in Fig. 30 is a phase demodulator of the synchronization signal. The output indicates the length of the code with two consecutive edges of the signal Fig. 31 . The Design Methodology with System Generator in Simulink of a FHSS Transceiver on FPGA 309 unipolar square 9 MHz carrier is converted to bipolar in this .