tailieunhanh - Adaptive Filtering Part 14

Tham khảo tài liệu 'adaptive filtering part 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 380 Adaptive Filtering Fig. 19. Design criteria for prototype band-stop filter H z centered at z 2 with bandwidth of z 2 band edges at z 4 and 3z 4 required to implement a tunable bandwidth band-stop filter using the three-way complex heterodyne circuit of Figure 9. Fig. 20d. Tunable bandwidth Bs filter W 3n 8 Fig. 20c. Tunable bandwidth BS filter w0 w 4 Fig. 20. Tunable bandwidth linear-phase band-stop filter using three-way complex heterodyne circuit Adaptive Heterodyne Filters 381 Figure 20 shows the tunable bandwidth band-stop filter. First when w0 0 we get the frequency response shown in Figure 20a which is the prototype filter convolved with itself H z H z . Thus we have over 80db attenuation in the stop band and the desired less that 3db ripple in the pass-band. The prototype filter is Band-Stop centered at z 2 with bandwidth of z 2 125 to 375 on the x-axis . Figure 20b shows the circuit with w0 rc 16. This tunes the lower band edge to z 2 - z 4 z 16 5w 16 on the x-axis of Figure 18b and the upper band edge to z 2 z 4 - x 16 11 16 on the x-axis of Figure 20b . Figure 20c shows the circuit with w0 rc 8. This tunes the lower band edge to z 2 - z 4 z 8 3 8 on the x-axis of Figure 20c and the upper band edge to z 2 z 4 - z 8 5 8 on the x-axis in Figure 20c . Figure 20d shows the circuit with w0 3 16. This tunes the lower band edge to z 2 - z 4 3z 16 7x 16 on the x-axis of Figure 20d and the upper band edge to z 2 z 4 - 3z 16 9 16 on the x-axis of Figure 20d . Notice that the attenuation of the tuned band-stop filters is over 40db which is the same stop-band attenuation as the prototype filter. All of these filters retain the linear-phase property of the prototype filter that was designed using the Parks-McClellan algorithm. Summary of three-way tunable complex heterodyne filter Azam s technique The Three-Way Complex Heterodyne Technique is capable of designing tunable center frequency band-stop and notch filter tunable