Qpsk and oqpsk modulation signal processing stack exchange. The oqpsk demodulator baseband block applies pulse shape filtering to the input waveform and demodulates it using the offset quadrature phase shift keying oqpsk method. The transmitter includes the bit generation subsystem, the qpsk modulator block, and the raised cosine transmit filter block. Oqpskmodulator object modulates the input signal using the offset quadrature phase shift keying oqpsk method and applies pulse shape filtering to the output waveform. The first 26 bits are header bits, a bit barker code that has been. The generated executable runs several times faster than the original matlab code. These builtin functions or toolboxes hide a lot of background computations. The bit generation subsystem uses a matlab workspace variable as the payload of a frame, as shown in the figure below.
To perform qpsk modulation and demodulation, you can use the pskmod and pskdemod functions by setting the order of modulation to 4. As usual in this kind of modulation, symbols chips have an halfsine shape, and the q channel has a 90 degree half simbol offset with respect to the i channel. Matlab code for qpsk modulation and demodulation mathworks. I intend to show how the theoretical aspects of a digital modulation demodulation system can be translated into simulation models, using elementary matrix operations in matlab. The function upsamples by a factor of 2, because oqpsk does not permit an odd number of samples per symbol.
This example simulates digital communication over an awgn channel. Correct a fixed symbol timing offset on a noisy qpsk signal by using the symbol synchronizer block. The first thing i have to do and perhaps the most difficult is removing the frequency offset from the received i and q signals. Uses a barker code to perform frame synchronization, phase ambiguity resolution, and demodulation.
The oqpsk demodulator baseband block applies pulse shape filtering to the input waveform and demodulates it using the offset quadrature phase shift keying. Cpm using a special set of symbols with restrictions on bit ordering and a special frequencypulse filter. The receiver addresses practical issues in wireless communications, such as carrier frequency and phase offset, timing offset and frame synchronization. Oqpsk demodulation search and download oqpsk demodulation open source project source codes from.
Matlab code for qpsk modulation and demodulation file. Demodulation using oqpsk method matlab mathworks italia. Offset quadrature phase shift keying modulation and demodulation objectives. For other exploration options, refer to the qpsk transmitter and receiver example using simulink. Qpsk and ofdm with matlab system objects open live script this example shows how to simulate a basic communication system in which the signal is first qpsk modulated and then subjected to orthogonal frequency division multiplexing. Design and implementation of a qpsk demodulator supervisor dr. Msk modulation and demodulation file exchange matlab.
The oqpsk modulator baseband block modulates the input signal using the offset quadrature phase shift keying oqpsk method and applies pulse shape. Satya prasad majumder submitted by md mubeenul haq khan student id. For qpsk, you want to have a message signal with possible values of 0, 1, 2 or 3 as an input to the qpsk modulator block. Set usecodegen to true to run the executable generated by codegen instead of the matlab code. Qpskdemodulatorname,value creates a qpsk demodulator object, h, with each specified property set to the specified value. All communications toolbox demodulator functions, system objects and blocks can demodulate binary. Qpskdemodulator creates a demodulator system object, h. The proposed technique is more robust to phase noise and consumes up to 89.
Qpsk receiver using analog devices ad9361ad9364 matlab. Each stream of odd bits quadrature arm and even bits inphase arm are converted to nrz format in a parallel manner. Also, the data decoder compares the regenerated message with the transmitted message and calculates the ber. Qpskdemodulatorphase, name, value creates a qpsk demodulator object, h. In this implementation, a splitter separates the odd and even bits from the generated information bits. The payload bits are descrambled, and printed out to the simulink diagnostic viewer at the end of the simulation. Matlab code for qpsk modulation and demodulation has been developed according to conventional. Offset quadrature phase shift keying oqpsk is a another of phaseshift keying accentuation application 4 altered ethics of the appearance to transmit. The pskmod function is elaborated upon here, with the example of qpsk modulation provided, and the pskdemod function is elaborated upon here, with an example of the entire process. This object has the phaseoffset property set to phase, and the. This paper presents a new practical qpsk receiver that uses digitized samples of incoming qpsk analog signal to determine the phase of the qpsk symbol.
This matlab function demodulates the complex envelope of an oqpsk modulated signal. After that, i want to introduce some random carrier frequency offsets in various sub carrier frequencies. You can specify additional namevalue pair arguments in any order. Implementing qpsk modulation and demodulation matlab. This offset may be modeled by a gaussian rv with rms value equal to to 12 percent of the frequency spacing. Study and analysis of qpsk modulation and demodulation with variable bit pattern and frequency. A novel sample based quadrature phase shift keying demodulator. Qpsk, oqpsk, dqpsk modulator and demodulator trainer kit. Script for msk modulation demodulation and computing ber for different ebn0 in awgn. You clicked a link that corresponds to this matlab command.
Qpsk modulation and demodulation with matlab and python. The phase offset estimator subsystem determines this phase shift. Offset quadrature phase shift keying demodulation mathworks. Offset qpsk also converts the serial bit stream into two parallel bit streams in which the bit intervals. The code of qpsk modulation and demodulation technique has been developed. The random integer generator block should do what youre looking for. Demodulation using oqpsk method simulink mathworks india. Meassetup digital demod properties format tab format. Meaning of q and i in all software qpsk communication systems. Qpsk modulator and demodulator matlab answers matlab. For qpsk demodulator, a coherent demodulator is taken as an example. In coherent detection technique the knowledge of the carrier frequency and phase must be known to the receiver.
Oqpskdemodulator object applies pulse shape filtering to the input waveform and demodulates it using the offset quadrature phase shift keying. The input is a baseband representation of the modulated signal. This matlab function modulates the input signal, x, using offset quadrature phase shift keying oqpsk. Use this object to modulate the input signal using the quadrature phase shift keying qpsk method. Can a qpsk demodulator with some changes demodulate oqpsk data. All communications toolbox demodulator functions, system objects and blocks can demodulate binary data using either hard decisions or soft decisions. The receiver addresses practical issues in wireless communications, e.
Oqpskdemodulator creates a demodulator system object. You can specify additional namevalue pair arguments in any order as name1,value1. This object demodulates the input signal using the quadrature phase shift keying qpsk method. Demodulate using qpsk method matlab mathworks united. Oqpskmodulator object modulates the input signal using the offset quadrature phase shift keying oqpsk method and applies pulse shape filtering.
Description the oqpsk demodulator baseband block applies pulse shape filtering to the input waveform and demodulates it using the offset quadrature phase shift keying oqpsk method. Modulation using oqpsk method matlab mathworks italia. It has the same phase relationship with qpsk, and is also divided into two. It is sometimes alleged staggered quadrature phase shift keying sqpsk. The function runsdruqpsktransmitter implements the qpsk transmitter using two system objects, qpsktransmitter and comm. It shows how to model several parts of the qpsk system such as modulation, frequency and phase recovery, timing recovery, and frame synchronization. You may run this program at different version of matlab such as. Such standards find application in home automation and sensor networking and are highly relevant to the internet of. I have an iq data of qpsk modulation, the data is is smeared and i have to correct the phase offset that causes the smearing problem, how can i apply the phasedlocked loop or the costas loop on this stage of iq data to correct the phase offset problem. Demodulation using oqpsk method simulink mathworks. Digital communication v18 offset and shifted quadrature phase shift keying oqpsk you can find the presentation slides at. Qpskmodulator name, value creates a qpsk modulator object, with each specified property set to the specified value. Qpsk demodulation problem due to apparent transmitter clock.
Each stream of odd bits quadrature arm and even bits inphase arm are converted to. On the contrary, the conventional qpsk demodulation process where it uses coherent detection technique. This can be achieved by using a pll phase lock loop at the receiver. The output is a baseband representation of the modulated signal. This object can jointly matchfilter and decimate a waveform, and demodulate it using the offset quadrature phase shift keying oqpsk method. Or, you could still use the bernoulli generator block with the output set to 2 samples per frame, and configure the qpsk modulator block to accept bit. Mathworks is the leading developer of mathematical computing software for engineers and scientists. The receiver addresses practical issues in wireless communications, such as carrier frequency and phase offset, timing offset. Harddecision mpsk demodulator m 8 floatingpoint signal diagram for nontrivial phase offset for m 8, in order to improve speed and implementation costs, no derotation arithmetic is performed when phaseoffset is 0.
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