QPSK调试与解调程序

clear all close all 参数 fcarr 2e3 Carrier frequency Hz B 1e3 Rate of symbol Baud nsamp 16 oversample rate fs nsamp B Sampling frequency Hz Fn fs 2 Nyquist frequency Ts 1 fs Sampling Time M 4 NumBit 2000 Number of bits in one frame NumMont 100 SNR dB 10 只能输入一个信噪比值 SNR 10 SNR dB 10 DataTX randint 1 NumBit 产生ZR信号 signal mapping DataTX M 产生NZR信号 for i 1 nsamp length signal Izero i I fix i 1 zero 1 if rem i nsamp 1 signalsam i signal fix i 1 nsamp 1 else signalsam i 0 end end delay 8 延迟 rolloff 0 25 滚降因子 n o 5 滤波器阶数 或取50 N 2 nsamp n o psf rcosfir rolloff n o fs B fs sqrt signal I conv real signalsam psf 成型波 signal Q conv imag signalsam psf 成形波 for i 1 nsamp length signal N t i i 1 fs s I i signal I i sqrt 2 cos 2 pi fcarr t i s Q i signal Q i sqrt 2 sin 2 pi fcarr t i end signal tx s I s Q 经过信道 Es 1 Eg 1 Es本来等于Eg 2 但是前面的载波幅度为sqrt 2 所以这里的Es 1 EsN0 dB 10 log10 nsamp SNR dB 计算出Es N0的值 单位是dB N0 1 10 EsN0 dB 10 noise randn 1 length signal tx sqrt N0 noise 0 signal tx n signal tx noise 带有噪声的信号 QPSK receiver demodulation fai0 30 pi 180 fai0 15 pi 180 fai0 45 pi 180 fai0 0 v 0 00002 f cL fcarr v B f cL fcarr for i 1 nsamp length signal N s rI i signal tx n i sqrt 2 cos 2 pi f cL t i fai0 s rQ i signal tx n i sqrt 2 sin 2 pi f cL t i fai0 end matched filter mf rcosfir rolloff n o nsamp fs sqrt signal rI conv s rI mf signal rQ conv s rQ mf data selection for i 1 nsamp length signal Isel i signal rI i N Qsel i signal rQ i N end sample for i 1 length signal signal rI s i Isel i 1 nsamp 1 signal rQ s i Qsel i 1 nsamp 1 end temp signal rI s j signal rQ s rbit demapping temp M figure plot signal kx title 原始信号星座图 axis 1 2 1 2 1 2 1 2 grid on figure 2 plot temp kx title 接收端信号星座图 axis 1 2 1 2 1 2 1 2 grid on number of errors bit error rate biterr DataTX rbit function output mapping input M scale log2 M if M 2 Constel 1 1 BPSK for i 1 length input output i Constel input i 1 end else input reshape input scale length input scale if M 4 Constel 1 1 for i 1 size input 2 I out i Constel input 1 i 1 Q out i Constel input 2 i 1 end output I out j Q out sqrt 2 end if M 16 Constel 3 1 1 3 for i 1 size input 2 if input 1 2 i 0 0 I out i 3 elseif input 1 2 i 0 1 I out i 1 elseif input 1 2 i 1 1 I out i 1 elseif input 1 2 i 1 0 I out i 3 end if input 3 4 i 0 0 Q out i 3 elseif input 3 4 i 0 1 Q out i 1 elseif input 3 4 i 1 1 Q out i 1 elseif input 3 4 i 1 0 Q out i 3 end end output I out j Q out sqrt 10 end end function output demapping input M 解映射 生成调制星座集 if M 2 for i 1 length input if real input i 0 output i 1 elseif real input i 0 elseif real input i 0 elseif real input i 0 elseif real input i 0 output 2 i 1 2 i 0 1 end end elseif M 16 constel 3 3j 1 3j 1 3j 3 3j 3 j 1 j 1 j 3 j 3 j 1 j 1 j 3 j 3 3j 1 3j 1 3j 3 3j sqrt 10 bitstream 0 0 1 0 0 1 1 0 1 1 1 0 1 0 1 0 0 0 1 1 0 1 1 1 1 1 1 1 1 0 1 1 0 0 0 1 0 1 0 1 1 1 0 1 1 0