Draw labelled block diagram the map correlation receiver

UNIVERSITY OF LONDON IMPERIAL COLLEGE OF SCIENCE TECHNOLOGY AND MEDICINE	[MSc-C2, E401, I411]

Comments for Question Q1:
� Question Q1 has 20 multiple choice questions numbered 1 to 20.

� Circle the answers you think are correct on the answer sheet provided.� There is only one correct answer per question.

Question-2


									PSD (f)=		N !	rect š		f		›
									PSD (f)=		2	rect š		2B		›
If a correlation receiver is used, estimate the probability of error, :eß as a function of -! , EUE, and and the a priori probabilities Pr Ð H ) ß Pr Ð H ) (40%)
		is the likelihood ratio threshold defined by the chosen decision criterion,

	3	is the time cross-correlation between signals.

choose H "		if K �	r threshold		K œ	X-= ' !		r t s t dt		�	X-= ' !
choose H "		if K �	r threshold		r threshold				ln-	"	X-= ' !		# Š s t Ð Ñ		�		# s t Ð Ñ
otherwise, choose H!				Ü	r threshold		´		Ð	2	X-= ' !		# Š s t Ð Ñ		�		# s t Ð Ñ	‹
where <Ð>Ñ
correlated signals with cross-correlation coefficient , and a correlation receiver which operates on the Bayes-decision criterion with the following costs:

a) Consider an 7-sequence waveform ,Ð>Ñ of period RX- partial autorrelation function over QX with Q � Rß					with
i.e. V ,ßQ	"		,Ð>ÑÞ,Ð> � ÑÞ.>
i.e. V ,ßQ	QX-		,Ð>ÑÞ,Ð> � ÑÞ.>
		Ð Ñ	for	� RX �	7	� RX Þ	(20%)
b) A BPSK direct sequence spread spectrum system (BPSK/DS-SSS) has a PN-code rate of 10 Mchips per second and a binary message rate of 1000 bits per second. The EUE at the receiver's input is 100 and the double-sided power spectral density of the received noise is 0.5‚10�8 Watts per Hz. For this system, in which the correlation time is exactly one message bit, what would be the receiver's synchronization errors ( , ) which would provide code noise power equal to 3.75‚10�) W, knowing that if 7 � X- then the code noise is constant and equal to 1.5‚10�( W. (80%)

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