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<HTML><HEAD><TITLE>EX-3: Binary Phase Shift Keying</TITLE>
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<H2>EX-3: Phase Shift Keying</H2>
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<TD><IMG border=0 height=100
src="Binary Phase Shift Keying.files/eyeemboss.gif" units="pixels"></TD>
<TD>In this exercise, you will design a BPSK detector to process the BPSK
modulated data contained in the file <TT>bpskdata.mat</TT>
</TD></TR></TBODY></TABLE>
<HR>
<H2>Specifications</H2>
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<TD vAlign=center><IMG
src="Binary Phase Shift Keying.files/bpskconst.gif">
<TD vAlign=center><PRE> normalized symbol rate: 1/8 bit/sample
normalzed carrier frequency: 0.25 cycles/sample
carrier phase: 0°
symbol clock offset: 0 sec
pulse shape: Square Root Raised Cosine(SRRC) (roll-off = 50%, span=12 symbols)
average energy 1 Joule
input file: bpskdata.mat
input message length: 119 symbols (bits)<PRE></PRE></PRE></TD></TR></TBODY></TABLE>
<P>
<HR>
<H2>Preliminary Design</H2>
<H3>Design the Detector</H3><IMG
src="Binary Phase Shift Keying.files/bpskmf.gif">
<P>
<P>Design the BPSK detector using blocks from the SIMULINK Block Library and the
Communications Blockset Library.
<H3>Test the Detector Design</H3>Test your design using the following procedure:
<OL>
<LI>Design a modulator (below) to meet the above specifications except make
the input the four symbol sequence <TT>1 0 0 1</TT>
<P><IMG src="Binary Phase Shift Keying.files/bpskmod.gif">
<P></P>
<LI>Connect the output of your modulator to the the input of your detector.
<P></P>
<LI>Connect the output of your detector to a <B>To Workspace</B> block. (Be
sure to open the Properties Dialog Window and set the Save format to matrix.)
<P></P>
<LI>Set the simulation parameters as follows: <PRE> Start Time: 0.0
Stop Time: (12+4+1)*8
Solver options Type: Fixed-step
discrete (no continuous states)
Fixed step size: 1
</PRE>Note: The stop time is computed as follows: 12 = span of the filter
(half the span is the delay at the modulator, half the span is the delay at
the detector); 4 = the number of data symbols; 1 = the one bit (or symbol)
delay to allow proper phasing of the downsample operation in the detector; 8 =
the number of samples/symbol.
<P></P>
<LI>Run the simulation and plot the received signal r[n] and the matched
filter output on the same set of axes.
<P></P>
<LI>Adjust the delay on the Downsample block to obtain the correct sybmol
timing.
<P></P>
<LI>Does the workspace variable agree with the input sequence (<TT>1 0 0
1</TT>)? </LI></OL>
<HR>
<H2>Exercise</H2>
<OL>
<LI>Replace the modulator blocks with the <B>From File</B> block and set the
Filename to: <TT>bpskdata.mat</TT>
<P></P>
<LI>Set the simulation parameters as follows: <PRE> Start Time: 0.0
Stop Time: (12+119+1)*8
Solver options Type: Fixed-step
discrete (no continuous states)
Fixed step size: 1
</PRE>
<LI>Run the simulation.
<P></P>
<LI>The last 119 bits of the detector output represent seventeen ASCII
characters. Determint the message using either your matlab script or the
on-line <A>ASCII
table</A>.
<P></P>
<LI> Print your answer and the SIMULINK model that contains your detector design.
<P></P>
<P></P><B>
Note</B>: Please specify the parameters you choose in each block if necessary.
<P></P>
<LI>Please finish this exercise on the due data. </LI></OL>
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