07-Class.10.Problems - ECE155A PROBLEMS Vlad Dorfman Class...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ECE155A PROBLEMS Vlad Dorfman Class #10 Due: 2/19/07 1. Noise Enhancement. Let s(t) be the Lorentzian step response of the channel ( s(t) = 1/(1+(2*t/PW50)^2) ), and suppose we design a zero-forcing linear equalizer with target z(t)=sinc(t/T). If sampled, z(kT) = (k) and therefore will have no ISI. The formula for the frequency response of the continuous zero-forcing equalizer is = otherwise S T G T , ), ( ) ( The frequency response of the Lorentzian is 2 50 50 2 ) ( PW e PW S = a. Plot G ( e j ), the frequency response of the equalizer for PW50=1 and D=PW50/T=1.0, 1.6, 2.0 ,and 2.5. Organize your M-files as a script, calling a function eq_fun(D,PW50). In your script file set PW50=1, then call eq_fun(D,PW50) with the requested values of D. (Comment: the problem shows what happens if different numbers of bits are placed into the constant area; this is represented by the PW50 value which is the same for all cases with only the density D changing). b. Calculate the noise power at the output of the equalizer for the above values of normalized density D . If you cannot find an analytical solution, you may use a computer to make an approximation, setting 2 = 1 in your eq_fun. Hint: For a linear system that has a FT magnitude |H( )|, and input random process X(t) with power spectral density S X ( ), the output power spectral density will be S Y ( ) = |H( )| 2 S X ( ). c. Make your conclusions as to dependency of noise enhancement on parameter D assuming the target z(t)=sinc(t/T). 2. Zero-Forcing Equalizer Implementation in Frequency Domain Consider a discrete-time channel impulse response h [ k ] defined as h (-2)=-2, h (-1)=-0.5, h (0)=5, h (1)=2, h (2)=1, h (k)=0 for |k| > 2. Use Matlab commands fft and ifft to determine (which is approximation, since fft...
View Full Document

Page1 / 4

07-Class.10.Problems - ECE155A PROBLEMS Vlad Dorfman Class...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online