hw9 - to a receiver at the listening end. The receiver (not...

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Assignment #9 Fri 10/07/05 1(15). The signal x ( t ) is applied to a system with impulse response, h ( t ). ( 29 ( 29 4 4 3 cos cos ) ( π - + + = t t t x ) 2 ( sinc 2 ) ( t t h = y ( t ) Find the equation of the steady-state output, y ( t ). 2(30). A periodic square wave, x ( t ), with period T = 4, is applied to the lowpass filter ) ( ) ( ϖ H t h , shown below. x ( t ) 1 H( ) ... ... 1 t y ( t ) = ? -1 -3 0 3 Find the equation of the output signal y ( t ). 3(15). Sketch the Fourier transform of ) 4 cos( ) ( ) ( t t x t w = , where < + + - < - - - = else X , 0 1 2 , 2 1 1 2 , 2 1 ) ( 4(40). A speech scrambler design to prevent electronic eavesdropping is outlined below. The input signal ) ( t x is garbled by changing its frequency content via filters. The garbled output ) ( t y is then transmitted
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Unformatted text preview: to a receiver at the listening end. The receiver (not shown) sequentially undoes all the filtering steps done at the transmitter. The diagram below represents only the transmitter filtering operations. Highpass Filter Lowpass Filter H 1 ( ) H 2 ( ) 1 1 x ( t ) a ( t ) b ( t ) c ( t ) y ( t )-20 0 20 -15 0 15 cos(20 t ) cos(30 t )-2-1 1 2 3 4 (a) Sketch ) ( A . Show all amplitudes and frequencies. Label all axes. (b) Sketch B ( ) and label the axes. (c) Sketch C ( ) and label all important points. (d) Sketch D ( ) and label all important points. Assume X ( ) 1...
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