How to generate BPSK signal
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Meshari Alsahli
le 20 Avr 2020
Commenté : Jaweed Raza
le 16 Sep 2023
- Generate 1000 random binary data bits.
- Convert unipolar to bipolar in the databits.
- Modulate the bipolar bits with Binary Phase Shift Keying (BPSK).
- Multiply the baseband BPSK with a carrier fc = 100 Hz.
- The modulated BPSK signals will be transmitted through a Noiseless channel. At the receiver side demodulate the received signal by multiplying it with a carrier and passing it through a Low Pass Filter (LPF).
- Decode the BPSK signal using match filtering and sgn function.
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Usama Saleem
le 27 Déc 2021
: Apply the concept of conversion of a double word into another word and implement it on Arduino and verify with the help of an Example.
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MathWorks Support Team
le 13 Juil 2021
Modifié(e) : MathWorks Support Team
le 13 Juil 2021
% Set up
% Specified parameters
M = 2; % Modulation order (BPSK)
nData = 1000; % Number of bits
Fc = 100; % Carrier frequency, Hz
% Assumed parameters
Fb = 100; % Bit (baud) rate, bps
Fs = 8*Fc; % Sampling frequency, Hz
Ts = 1/Fs; % Sample time, sec
Td = nData/Fb; % Time duration, sec
spb = Fs/Fb; % Samples per bit
fSpan = 4; % Filter span in symbols
% Visualize the spectrum of baseband BPSK & modulated carrier
specAn1 = dsp.SpectrumAnalyzer("SampleRate", Fs, "Method","Filter bank","AveragingMethod","Exponential","Title", "Pulse Shaped Baseband BPSK");
specAn2 = dsp.SpectrumAnalyzer("SampleRate", Fs, "Method","Filter bank","AveragingMethod","Exponential","Title", "BPSK Modulated Carrier");
% Transmitter
% Generate random data bits
data = randi([0 M-1],nData,1);
% Modulate and plot the data
% pskmod() effectively converts unipolar to bipolar bits and performs BPSK
% modulation
modData = real(pskmod(data,M));
% Pulse shape & upsample to match carrier's sampling rate. Pulse shaping is
% used to reduce intersymbol interference and to reduce spectral width of
% the modulated signal.
txFilter = comm.RaisedCosineTransmitFilter("FilterSpanInSymbols",fSpan,"OutputSamplesPerSymbol",spb);
txfilterOut = txFilter(modData);
specAn1(txfilterOut);
% Multiply modulated & pulse shaped signal with carrier
sine = dsp.SineWave("Frequency",Fc,"SampleRate",Fs,"ComplexOutput",false,"SamplesPerFrame",Td/Ts);
carrier = sine();
txSignal = txfilterOut .* carrier;
specAn2((txSignal));
% Receiver
% Multiply received signal with carrier
rxSignal = txSignal .* conj(carrier);
% Low pass match filter to account for pulse shaping
rxFilter = comm.RaisedCosineReceiveFilter("FilterSpanInSymbols",fSpan,"InputSamplesPerSymbol",spb,"DecimationFactor",spb);
rxFilterOut = rxFilter(rxSignal);
% Demodulate
% For BPSK, pskdemod() is equivalent to sign function
dataOut = pskdemod(rxFilterOut,M);
% Each of the tx and rx filters introduces a delay of fSpan/2 symbols, for
% a total delay of fSpan symbols (= bits for BPSK). Delay received bits by
% fDelay for accurate comparison with transmitted bits.
fDelay = fSpan;
[numErr, ber] = biterr(data(1:nData-fDelay),dataOut(fDelay+1:nData))
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Jaweed Raza
le 16 Sep 2023
I tried running the above scripts but generated that there are errors in
specAn1 = dsp.SpectrumAnalyzer("SampleRate", Fs, "Method","Filter bank","AveragingMethod","Exponential","Title", "Pulse Shaped Baseband BPSK");
specAn2 = dsp.SpectrumAnalyzer("SampleRate", Fs, "Method","Filter bank","AveragingMethod","Exponential","Title", "BPSK Modulated Carrier");
I am not sure why these errors are generated. The lines are identical for SpecAn1 and SoecAn2. What's the difference and how do they differentiate to display the pulse and spectrum?
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Maadhav Akula
le 23 Avr 2020
You can use the follllowing system objects to perform BPSK Modulation and Demodulation:
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