$1$ mark

ii$.$ Design a system that will work as an unscrambler, i$.$e$.,$ recover $m(t)$ from $s(t).$

ECE$316$S Final Examination

APRIL $28,2011$

$($b$)$ We wish to transmit three message signals $m_1(t),m_2(t)$ and $m_3(t).$ Signals $m_1(t)$ and $m_2(t)$ are bandlimited to $500$ Hz $,$ while $m_3(t)$ is bandlimited to $1000$ Hz $.$

The message $m_1(t)$ is DSB$-$modulated using carrier frequency $f_1=2000Hz.$ The other two messages, $m_2(t)$ and $m_3(t),$ are SSB$-$modulated using carrier frequencies $f_2$ and $f_3,$ respectively, where $f_2{f}_3{f}_1.$

$4$ marks

$i.$ Determine the smallest values $of{f}_2$ and $f_3$ such that one can recover each $of$ the three message signals using ideal filters and denodulators.

$2$ marks

$ii.$ What $is$ the total bandwidth used?

$2.(16$ marks$)$ Frequency Modulation: The three parts $of$ this question are independent.