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quiz4_08 - type of filter algorithm you would use for...

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ECEN 487 QUIZ 4 NAME:_________________ 1. You are a DSP engineer for Sony Corporation. Your assignment is to design the digital portion of the sample rate conversion function in the next Bluray DVD player. The Bluray DAC runs at a sample rate of 96 ks/sec. You want to convert a CD sample rate of 44.1 ks/sec so it can be played at 96 ks/sec through the built in DACs. Assume the original audio bandwidth was limited to 20 kHz. Draw a block diagram of how you would implement the sample rate change efficiently. Specify ideal filter corner frequencies (in discrete-time radians per sample), gains, up-sample and down-sample rates, and state what filter architecture would be most efficient. For extra credit (2 points) specify the passband and stopband corner frequencies for a practical filter implementation that would include a transition band, and specify the
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Unformatted text preview: type of filter algorithm you would use for improved computational efficiency. L / M = 960 / 441 = 320 /147 L = 320, M = 147 G = L = 320 ± c (ideal) = min( ² / L , / M ) = / 320 (interpolating filter dominates) p (practical) = 2 ³ 20 kHz L ³ 44.1 kHz = 0.00283 = .0089 s (practical) = 2 ³ 24.1 kHz M ³ 44.1 kHz = 0.00342 = .0107 For efficency, implement the LPF as a polyphase decimating filter to reduce computational load by 147! You could also implement it as a polyphase upsampling filter, with a computational savings of 320. For super efficiency the commutator can skip M samples at a time, and you only compute the interpolator polyphase filter outputs when needed. This is a computational savings of (147)(320)!!!! ± L ² M H ( z ). LPF corner at c x [ n ] y [ k ]...
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