quiz 6

# quiz 6 - second for your final most efficient design....

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ECEN 487 QUIZ 6 NAME:____KEY_____ 1. You are an engineer working for Yaesu Electronics, Amateur Radio Division. Your assignment is to design the digital implementation of a narrowband bandpass filter for CW (Morse code) reception k the FT-897 amateur radio transceiver (this is the one I have). The passband width will be 100 Hz. This is just a 397 tap FIR filter. The signal sample rate is f s = 10 kHz. a) Draw a block diagram of how you would implement the filter efficiently. b) Determine the optimal window length L which is a power of two, i.e. L = 2 ν where is an integer. Consider only values of = {10, 12}. Specify window length L , number of samples overlapped θ , and computational burden in multiplies per

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Unformatted text preview: second for your final most efficient design. Assume L 2 log 2 L multiples per FFT. P = 397, = 396, Number of good points per window: N g = L- . mult. / sec = (wind/sec)(mult./wind) = ( f s / N g )(2 L 2 log 2 L + L ) = ( 10 4 L − 396 )( L log 2 L + L ) . Extract L points, overlap P-1 FFT L points FFT L points Zero pad to L points Extract last L - P + 1 points Concatinate IFFT L points x [ n ] x r [ n ] X r [ k ] h [ n ] H [ k ] Y r [ k ] y r [ n ] y [ n ] L = 4096 is optimal. ν L Number of multiplies × 10 6 8 256 No good: L < θ 9 512 4.41 10 1024 1.79 11 2048 1.49 12 4096 1.44 BEST!! 13 8192 1.47 14 16384 1.54 15 32768 1.62...
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## This note was uploaded on 03/16/2012 for the course ECEN 487 taught by Professor Dr.brianjeffs during the Winter '12 term at BYU.

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quiz 6 - second for your final most efficient design....

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