(Created page with "Category:ECE Category:QE Category:problem solving <center> <font size= 4> ECE Ph.D. Qualifying Exam </font size> <font size= 4> Comm...") |
|||
| Line 22: | Line 22: | ||
\begin{cases} | \begin{cases} | ||
0 & \omega<0 \\ | 0 & \omega<0 \\ | ||
| − | \dfrac{1}{2}hb-\dfrac{1}{2}hb(\dfrac{h-\omega}{h})^2=\dfrac{2\omega}{h}-\dfrac{w^2}{h^2} & 0<=\ | + | \dfrac{1}{2}hb-\dfrac{1}{2}hb(\dfrac{h-\omega}{h})^2=\dfrac{2\omega}{h}-\dfrac{w^2}{h^2} & 0<=\omega<h \\ |
1 & \omega>=h | 1 & \omega>=h | ||
| + | \end{cases} | ||
| + | </math><br> | ||
| + | b)<br> | ||
| + | <math>f_x(\omega)=\dfrac{\partialF_x(\omega)}{\partial\omega}</math><br> | ||
| + | <math>f_x(\omega)= | ||
| + | \begin{cases} | ||
| + | 0 & \omega<0 \\ | ||
| + | \dfrac{-2}{h^2}\omega+\dfrac{2}{h} & 0<=\omega<h \\ | ||
| + | 0 & \omega>=h | ||
\end{cases} | \end{cases} | ||
| − | </math> | + | </math><br> |
| + | |||
| + | c)<br> | ||
| + | <math>X(\omega)\bar=\int_{-\infty}^{\infty} \omegaf_x(\omega) dx =\int_{0}^{h} -\dfrac{2}{h^2}(\omega)^2 +\dfrac{2}{h}\omega d\omega</math> | ||
| + | |||
---- | ---- | ||
[[ECE-QE_CS1-2016|Back to QE CS question 1, August 2016]] | [[ECE-QE_CS1-2016|Back to QE CS question 1, August 2016]] | ||
[[ECE_PhD_Qualifying_Exams|Back to ECE Qualifying Exams (QE) page]] | [[ECE_PhD_Qualifying_Exams|Back to ECE Qualifying Exams (QE) page]] | ||
Revision as of 23:15, 18 February 2019
Communication Signal (CS)
Question 1: Random Variable
August 2016 Problem 1
Solution
a)
$ F_x(\omega)= \begin{cases} 0 & \omega<0 \\ \dfrac{1}{2}hb-\dfrac{1}{2}hb(\dfrac{h-\omega}{h})^2=\dfrac{2\omega}{h}-\dfrac{w^2}{h^2} & 0<=\omega<h \\ 1 & \omega>=h \end{cases} $
b)
$ f_x(\omega)=\dfrac{\partialF_x(\omega)}{\partial\omega} $
$ f_x(\omega)= \begin{cases} 0 & \omega<0 \\ \dfrac{-2}{h^2}\omega+\dfrac{2}{h} & 0<=\omega<h \\ 0 & \omega>=h \end{cases} $
c)
$ X(\omega)\bar=\int_{-\infty}^{\infty} \omegaf_x(\omega) dx =\int_{0}^{h} -\dfrac{2}{h^2}(\omega)^2 +\dfrac{2}{h}\omega d\omega $
