Bpsk demodulation for rf applications yuting toh may 12, 2017 in this report, binary phase shift keying bpsk demodulation is discussed for an rf application. Quadrature phase shift keying qpsk is a form of phase shift keying in which two bits are modulated at once, selecting one of four possible carrier phase shifts 0, 90, 180, or 270 degrees. Qpsk transmitter using analog devices ad9361ad9364 matlab. The example uses matlab commands to run a series of simulations with different input.
To learn more about digital modulation, see digital modulation. How to build and simulate a simple simulink model duration. The qpsk signal within a symbol duration is defined as. In this lab, you will observe the quadrature phase shift keying qpsk modulation and demodulation building simulink simulation. An optical qpsk modulator consists of 2 mz modulators, which further have a. The modulator and demodulator architecture principle of qpsk modulator in quadrature phase shift keying qpsk, two successive bits in the data sequence are grouped. Modulation using oqpsk method simulink mathworks india. Drag and drop mpam modulator baseband module into the model window. Drag and drop bpsk modulator baseband module into the model window. This block accepts a scalar or column vector input signal. Qpsk demodulator baseband makers of matlab and simulink. Qpsk transmitter using analog devices ad9361ad9364. The example also illustrates how you can use simulink and matlab together.
Sep 01, 2016 qpsk modulation in matlab awgn channel part 1 2016 matlab tutorial. For digital modulator demodulator applications, altera provides a quadrature phaseshift keying qpsk modem reference design as an example design. 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. Modulate and plot the constellations of qpsk and 16psk signals. The ber performance improvement for qpsk modulation when using loglikelihood ratio llr instead of harddecision demodulation in a convolutionally coded communication link. This example shows how to use the xilinx zynqbased radio support package with simulink to implement a qpsk transmitter. If you use baseband modulation to produce the complex envelope y of the modulation of a message signal x, then y is a complex.
Mapping the symbols in this manner allows for a 2 bit value to be used to represent each symbol. The qpsk demodulator baseband block demodulates a signal that was modulated using the quadrature phase shift keying method. Communications toolbox modulation digital baseband modulation pm. Matlab pskmod mathworks makers of matlab and simulink. Modulate using quadrature phase shift keying method. The dqpsk modulator baseband block modulates using the differential quadrature phase shift keying method. The qpsk modem reference design demo nstrates key features of the dsp development kit, stratix edition and dsp development kit, stratix professional edition.
Qam is a better modulation technique than 4 bit qpsk modulation technique. Matlab code for qpsk modulation and demodulation file. You can demodulate the transmitted message using the qpsk receiver using analog devices ad9361ad9364 model if you have a second sdr platform. A practical qpsk modulator implementation similar to. Various methods are presented but the costas loop is shown to be the most successful at obtaining. I just want to plot the qpsk baseband spectrum from the output data of the qpsk simulink block. Given a signal you are asked to perform baseband qpsk not on a carrier.
This model shows the implementation of a qpsk transmitter and receiver. Software defined radio using simulink tool to implement the ieee. 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 output is a baseband representation of the modulated signal. The bpsk modulator baseband block modulates using the binary phase shift keying method. Then, the second stage will be the implementation of qpsk using usrp hardware.
With llr demodulation, one can use the viterbi decoder either in the unquantized decoding mode or the softdecision decoding mode. Phase of the baseband signal changes from 45 deg, 5 deg, 225 deg, 315 deg 4 transitions2 bits per. This example describes the simulink implementation of a qpsk transmitter with the zynq and analog devices ad9361ad9364 radio platform. Communications toolbox provides tools for modulating and demodulating digital baseband signals using either matlab or simulink. Pdf hardware cosimulation of bpsk and qpsk for software. The qpsk modulator baseband block modulates using the quadrature phase shift keying method.
You can demodulate the transmitted message using the qpsk receiver using analog devices ad9361ad9364 model if. 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. Qpsk modulation and demodulation in matlab awgn channel duration. In most media for communication, only a fixed range of frequencies is available for transmission. This model shows filtered quadrature phase shift keying qpsk and minimum shift keying msk modulation schemes and visually compare them. Pdf in this thesis, we will discuss about a specific modulation technique known. The code of qpsk modulation and demodulation technique has been developed according to the theory. For information about the data types each block port supports, see supported data types. The third stage of our work was to connect qpsk modulator with qpsk demodulator directly without any external noise. Pdf modelling of ultrawide band system for qpsk modulation. The input is a baseband representation of the modulated signal. The receiver addresses practical issues in wireless communications, e. However the output of this block are the symbol coordenates in the signal space and when i use spectrum scope i dont get the theorical spectrum for the qpsk the sinc function. Then, the second stage will be understanding the impact of key parameters on the system performance.
Implementation of qpsk modulation on matlab simulation. Go to communications blockset modulation digital baseband modulation pm subfolder. The signal is then passed through an additive white gaussian noise channel prior to being demultiplexed and demodulated. Pdf design and implementation of quadrature phase shift keying. Qpsk modulation is the best choice for digital satellite transmission for a number of reasons satellite power transmission efficiency, antiinterference and comprehensive consideration of the size of the how to cite this paper. A modulator and a pulse shaping filter that perform qpsk modulation and root raised cosine pulse shaping. Bit error rate performance of qpsk modulation and ofdmqpsk system over. The qpsk modulator baseband block modulates using the. The theoretical description of qpsk modulation and demodulation are available in the book of communication system by simon haykin. 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. Now, you will need almost the same modules as in part 1. Demodulation using oqpsk method simulink mathworks espana.
These digital modules will be implemented as different modules and used as components in top level entities 2. An upconverter block that multiplies the modulated signal by a carrier frequency. Qpsk modulator and demodulator using fpga for sdr core. Qpsk modulator operates by separation of baseband data into i and q phases and then. Qpsk modulation in matlab awgn channel part 1 2016 matlab tutorial. In this lab, you will observe the ofdm modulation and demodulation building simulink simulation.
Research on carrier synchronization of qpsk based on simulink. The mpsk modulator baseband block modulates an input signal using mary phase shift keying psk. Modulation using oqpsk method simulink mathworks espana. Therefore, the four possible initial signal phases are and radians. The receiver demodulates the received symbols and outputs a simple message e. An sdr has been constructed, using the simulink tool, and implemented on the sparten3e. Pdf the paper presents the design of a bpsk and qpsk digital modulation scheme and its implementation on fpgas. You can also explore a nonhardware qpsk transmitter and receiver example that models a general wireless communication system using an awgn channel and simulated channel impairments with the qpsk transmitter. Modulate using quadrature phase shift keying method simulink. Dec 07, 2018 this feature is not available right now. The input must be a discretetime binaryvalued signal. Modulate using differential quadrature phase shift keying. Matlabsimulink software, the dspbased qpsk iq generator can be easily. The sdr device in this model will continuously transmit indexed hello world messages that are qpsk modulated onto a carrier with a specified center frequency.
Fi qpsk modulator and demodulator the results of the qpsk modulator at outputs qpsk transmitter block are shown below. Modulate using binary phase shift keying method simulink. Drag and drop bpsk demodulator baseband module into the model window. Modulation using oqpsk method simulink mathworks italia. The interference has a cubic nonlinearity which may be toggled on or off. Discrete plot is plotted between quadrature amplitude and inphase amplitude as shown in figure. We have discuss all blocks used in the qpsk simulink model as shown in fig 2.
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