ELEC426,Autumn,2017,Assignment3,Due:25May2017Page2 Q1 (3 Marks= XXXXXXXXXXAsshowninfigure1-1,theoutputofanoisesourceandtheoutputofasignalgeneratorare summedtogether.Theresultingsignalplusnoiseistheinputofasystem.Thesystemconsistsof thecascadecombinationof: Amplifier1,amixer(twoportfrequencyconverter),andamplifier2.Theblockdiagramofthis systemisshowninfigure1-1. Figure1-1.BlockDiagramofasignalgenerator,noisesource,amplifiers,andamixer. Thesignalisabandpassmodulatedsignalwitha1MHzbandwidth. Thecentrefrequencyofthesignalis900MHz. Amplifier1andamplifier2havebandpasstransferfunctioncharacteristics.Amplifier1hasacentre frequencyof900MHz.Themixerdown-convertsa900MHzsignalto100MHz.Amplifier2hasa centrefrequencyof100MHz.Bothamplifier1andamplifier2havenoiseequivalentbandwidthsof 10MHz.Theamplifiedandfrequencyconvertedsignaldoesnothaveanysignaldistortionatthe 50? loadresistor. Thenoisesourcehasanoisetemperature2,000Kelvin. ELEC426,Autumn,2017,Assignment3,Due:25May2017Page3 Thethreedevicesarespecifiedby: amplifier1, NoiseFigure=1.4dB, Gain=15dB, mixer, NoiseFigure=13dB, Gain=6dB, amplifier2, NoiseFigure=16.0dB, Gain=60dB. Itisrequiredtohaveasignaltonoiseratio, 16 dB s n dB P P ? ? ? ? ? ? ? ,atthe50? loadresistoratthe outputofamplifier2,where is the signal power and is the noise power. P P s n PartA Toachievethis,whatistherequiredRMS(rootmeansquare)signallevelatthesignalgenerator outputinvolts?Note,theoutputofthesignalgeneratorismeasuredacrossa50?resistive impedance. PartB Correspondingtothesignalgeneratoroutputthatachievesa 16 dB s n dB P P ? ? ? ? ? ? ? ,whatistherms voltageattheoutputofamplifier2involts? ELEC426,Autumn,2017,Assignment3,Due:25May2017Page4 Q2 (3 Marks) A bandpass radio signal s t? ? has complex envelope representation, ?? ?? ?? ?? ? ? Re where, , , , . c j ft j t st ste s t Ae e u t t u t t ? ? ?? ? ? ? ? ? ? ? ? ? ? ? ? XXXXXXXXXX ? ? The signal is put through a bandpass filter with impulse response h t? ? , where, ?? ?? ?? ?? Re where c j ft j t ht hte h t Ce e u t ? ? ?? ? ? ? ? ? ? 2 ? ? What is the output of the filter, yt t A ? ?asafunctionof , ,C, , , and ? ? ?? ? Hint: Re ,where and istheconvolutiono ? ? ?? ?? ?? ?? perator. c j ft yt yte yt st ht ? ? ?? ? ? ? ? ? 1 2 2 ? ? ? ? ELEC426,Autumn,2017,Assignment3,Due:25May2017Page5 Q3 (4 Marks) AcommunicationsystemusesQPSKmodulation. Thebiterrorraterequirementforthissystemis PB ? ? XXXXXXXXXXThetransmissionfrequencyis of ? 2.4GHz. The transmitter power is 1 Watt. The feedline loss between the transmitter and the transmit antenna is 2 dB. The transmit antenna is omnidirectional and has a gain of 0 dBi. The transmit antenna height is 20 meters For the receiver, the low noise amplifier has a noise figure of 7 dB, the feedline loss is 1.5 dB, the antenna temperature is 290 K, and the receive antenna gain is 3 dBi. The demodulator implementation loss is 1 dB. The receive antenna height is 1.5 meters. A. Assuming free space loss in the channel, plot the data rate that the link supports for distances between 100 meters and 20 km. Use a log-log graph to plot the data rate in bits/s as a function of distance, d, in meters. B. Assuming a two-ray propagation loss model, plot the data rate that the link supports from to20km,where t r t ro c c hh hh f d d ? c ? ? 4 4 . On the same graph as part A, plot the data rate in bits/s as a function of distance, d,inmeters.