Ex_3_Binary_PSK.rar_ex资源-CSDN文库

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在通信系统中，二进制相移键控（Binary Phase Shift Keying，简称BPSK）是一种常用的数字调制方式。这种调制技术通过改变载波信号的相位来传输二进制信息，即0和1。在"Ex_3_Binary_PSK.rar_ex"这个压缩包中，包含的是一个MATLAB实现的BPSK调制和解调的仿真程序，对于理解BPSK的工作原理和学习通信系统的模拟具有重要意义。我们要了解BPSK的基本概念。在BPSK中，通常选择一个正弦波作为载波，当发送0时，载波相位为0或π（根据不同的参考相位），而发送1时，载波相位变为180度或π。这种相位的改变使得接收端可以通过检测接收到的信号相位来判断发送的数据是0还是1。 MATLAB是进行通信系统仿真非常强大的工具，它提供了丰富的库函数和工具箱，如Signal Processing Toolbox和 Communications Toolbox，可以方便地实现各种调制解调算法。在"Ex_3_Binary_PSK"的仿真代码中，我们可以预期以下几个关键步骤： 1. **信息序列生成**：我们需要生成一个随机的二进制数据流，作为要传输的信息源。这通常通过使用randi()或rand()函数完成。 2. **BPSK调制**：将二进制序列转换为相位变化。当二进制值为0时，向量中的相应元素赋值为1（对应0度或π），为1时赋值为-1（对应180度或π）。然后，这些值乘以载波信号（通常是sine或cosine函数）生成调制后的基带信号。 3. **信道模型**：为了模拟真实世界的通信环境，通常会加入一些信道效应，如加性高斯白噪声（AWGN）或多径衰落等。在MATLAB中，可以使用awgn()函数添加噪声，或者自己创建衰落信道模型。 4. **接收端处理**：在接收端，首先需要进行解调。BPSK的解调通常采用鉴相器，比较接收到的信号相位与本地载波相位，从而判断出信息符号。在MATLAB中，可以通过计算两个复数的幅度相位差来实现。 5. **判决与误码率计算**：将解调后的信号与原始信息序列进行比较，计算错误的数量，进而得到误码率（Bit Error Rate, BER）。误码率是衡量通信系统性能的重要指标。 6. **可视化**：为了更好地理解仿真结果，可以绘制星座图、眼图以及误码率随信噪比变化的曲线。通过运行这个MATLAB仿真，我们不仅可以学习到BPSK的工作原理，还能深入理解通信系统中的信号处理过程，包括编码、调制、信道建模、解调以及性能评估。这对于通信工程的学习和研究至关重要。

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Ex_3_Binary_PSK.rar （6个子文件）

Ex_3_Binary_PSK

bpskdata.mat 17KB

Binary Phase Shift Keying.htm 4KB

Binary Phase Shift Keying.files

bpskmod.gif 3KB

bpskconst.gif 336B

bpskmf.gif 3KB

eyeemboss.gif 26KB

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD><TITLE>EX-3: Binary Phase Shift Keying</TITLE> <META content="text/html; charset=gb2312" http-equiv=Content-Type> <META content="MSHTML 5.00.2920.0" name=GENERATOR></HEAD> <BODY bgColor=#cccccc> <H2>EX-3: Phase Shift Keying</H2> <TABLE> <TBODY> <TR> <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> <TABLE> <TBODY> <TR> <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> <HR>

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