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. Each techbook is provided with detailed multimedia learning material which covers basic theory, step by step procedure to conduct the experiment and other useful information. The oqpsk modulation is a psk modulation, using 2 bits per symbol and a delay of one bit in the in quadrature signal refer to optisystem component library, oqpsk pulse generator. This can be achieved by using a pll phase lock loop at the receiver. This block accepts a scalar or column vector input signal. For example, y stepobj,x and y objx perform equivalent operations. Modulation using oqpsk method simulink mathworks india. In coherent detection technique the knowledge of the carrier frequency and phase must be known to the receiver. Msk modulation stands for minimum shift keying modulation. Digital modulation, from ask to oqp5k is it qpsk or 4qam. Algorithms for efficient computation of convolution. One way to communicate a message signal whose frequency spectrum does not fall within that fixed frequency range, or one that is otherwise unsuitable for the channel, is to alter a transmittable signal according to the information in your message signal. The oqpsk demodulator baseband block applies pulse shape filtering to the input waveform and demodulates it using the offset quadrature phase shift keying. The only real trick is how to get it into a locked condition, and there are many ways to do that.

Scientech techbook 2808 provides an extensive hands on learning on qpsk, oqpsk, dqpsk modulator and demodulator. For qpsk demodulator, a coherent demodulator is taken as an example. This model shows the implementation of a qpsk transmitter and receiver. Compare psk and pam modulation schemes to demonstrate that psk is more sensitive to phase noise. Using matlab to realize the success of this program, soqpsk, modulation, and draw out the time domain waveforms of soqpsk, phase. The simple way, if you have a lot of time, is to sweep the frequency very slowly. To learn more about digital modulation, see digital modulation. Matlab code for qpsk modulation and demodulation file. The output values are integer representations of two bits and range from 0 to 3 when you set this property to true, the object outputs a binary column vector of bit values. The above is the reason why the scheme is called minimum shift keying. They are configured for framebased processing with bit signal inputs. Matlab code for qpsk modulation and demodulation in matlab. When you set this property to false, the object outputs a column vector of integer values with a length equal to the number of demodulated symbols.

The oqpsk modulator baseband block modulates the input signal using the offset quadrature phase shift keying oqpsk method and applies pulse shape. The output plots and mathematical equations of msk modulation matlab code are mentioned. The qpsk demodulator baseband block demodulates a signal that was modulated using the quadrature phase shift keying method. The function upsamples by a factor of 2, because oqpsk does not permit an odd number of samples per symbol. The power spectral density of msk is shown in the figure 10 for di. Qpsk demodulation problem due to apparent transmitter. The output vector length is twice as long as the number of input symbols. Take system delays into account when comparing transmitted data with received data, such. I have implemented qpsk modulation and demodulation system but does not give the 4 constellation points from the qpsk modulator block. 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 input is a baseband representation of the modulated signal.

Need help to write matlab code for oqpsk modulation. Matlab code for qpsk modulation and demodulation has been developed according to conventional theory. File list click to check if its the file you need, and recomment it at the bottom. Implementing qpsk modulation and demodulation matlab. As for the topics concerned, only the basic techniques of modulation and demodulation of various digital modulation techniques are covered.

Hello guys, i am looking for the basic modulation code of oqpsk modulation for matlab. Oqpskdemodulator object applies pulse shape filtering to the input waveform and demodulates it using the offset quadrature phase shift keying. This file includes oqpsk modulatian and demodulation simulink model. Oqpsk modulatian and demodulation by using simulink file. This file includes oqpsk modulatian and demodulation simulink model with rayleigh channel. All communications toolbox demodulator functions, system objects and blocks can demodulate binary. The output is a baseband representation of the modulated signal. I am using the berawgn function from matlab to calculate the ber for oqpsk but i am looking for an expression for this ber. Understanding the phasing method of single sideband demodulation. The signal is then passed through an additive white gaussian noise channel prior to being demultiplexed and demodulated.

The qpsk modulation and demodulation technique which is simulated according to theory by matlab programming. Demodulation using oqpsk method matlab mathworks italia. In qpsk, the data bits to be modulated are grouped into symbols, each containing two bits, and each symbol can take on one of four possible values. Oqpsk demodulation search and download oqpsk demodulation open source project source codes from. This example shows the oqpsk modulator baseband and oqpsk demodulator baseband blocks connected with no channel or impairments distorting the. The complete waveform simulation for the aforementioned qpsk modulation and demodulation is given next. Once locked, however, an oqpsk demodulator is essentially a qpsk demodulator that shifts one channel a halfsymbol somewhere before the slicer. Qpsk, oqpsk, dqpsk modulator and demodulator trainer kit. Modulation using oqpsk method matlab mathworks italia.

This example shows the oqpsk modulator baseband and oqpsk demodulator baseband blocks connected with no channel or impairments distorting the signal between them. This page of matlab source code covers msk matlab code. In most media for communication, only a fixed range of frequencies is available for transmission. This section of matlab source code covers bpsk,qpsk,16qam and 64qam modulation or data mapping matlab code. In the transmitter, spreading is done using a pn sequence at chip rate of 2 mcps and then the spreaded bits are modulated using oqpsk modulator. The output is displayed on to discretetime scatter plot scope and shows only 2 constellation points when i run the simulation. In the receiver side, oqpsk demodulation is done first,then the spreaded bits are despreaded using the delayed version of pn chip sequence. The simulation involves, generating random message bits, modulating them using qpsk modulation, addition of awgn channel noise corresponding to the given signaltonoise ratio and demodulating the noisy signal using a coherent qpsk receiver. Perform oqpsk modulation and demodulation and apply root raised cosine filtering to a waveform. Define simulation parameters and create objects for oqpsk modulation and demodulation.

The matlab scripts carry inline comments intended to help the reader understand the ow of implementation. Demodulation using oqpsk method simulink mathworks. Oqpsk modulatiandemodulation and pn code by using simulink. Starting in r2016b, instead of using the step method to perform the operation defined by the system object, you can call the object with arguments, as if it were a function. Oqpskmodulator object modulates the input signal using the offset quadrature phase shift keying oqpsk method and applies pulse shape filtering.

Modulation using oqpsk method matlab mathworks france. The oqpsk modulator baseband and oqpsk demodulator baseband blocks connected with no channel or impairments distorting the signal between them. With llr demodulation, one can use the viterbi decoder either in the unquantized decoding mode or the softdecision decoding mode. Qpsk modulation matlab code download free open source. Qpsk, oqpsk, cpm probability of error for awgn and flat. Oqpskmodulator object modulates the input signal using the offset quadrature phase shift keying oqpsk method and applies pulse shape filtering to the output waveform. This page covers modulation or mapping of binary data based on modulation type bpsk,qpsk,16qam and 64qam.

Stack overflow for teams is a private, secure spot for you and your coworkers to find and share information. The receiver demodulates the received symbols and outputs a simple message e. The following matlab project contains the source code and matlab examples used for matlab code for qpsk modulation and demodulation. Note that the main lobe of msk is 50% wider than that for oqpsk. This is the expected result because the psk constellation is circular while the pam constellation is linear. I have already written the code of qpsk but i cant understand the difference between this code and the oqpsk. Digital modulation and demodulation blocks incur delays between their inputs and outputs that result in an offset in the arrival time of the received data. Bpsk qpsk 16qam 64qam modulation matlab code matlab.

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