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Title:	A novel sample based quadrature phase shift keying (QPSK) demodulator
Authors:	Asraf Mohamed Moubark (P57643)
Supervisor:	Mohd Alauddin Mohd Ali, Prof. Dr.
Keywords:	Demodulator Frequency modulation detectors Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	7-May-2013
Description:	Quadratute Phase Shift Keying (QPSK) is a modulation scheme commonly used in wireless communication system due to its ability to transmit twice the data rate for a given bandwidth. Although QPSK is insensitive to amplitude noise but it is susceptible to phase noise which is worsened by Doppler shift. The objective of this work is to develop an implementable QPSK receiver that is more robust to phase noise and uses less power for transmission and operation. The proposed technique uses a sample and hold circuit to determine the phase of the QPSK symbol without the knowledge of incoming signal frequency. On the contrary, the conventional QPSK demodulation process requires Costas loop to determine the exact incoming signal frequency thus any variation in the frequency will cause phase noise. A QPSK symbol is sampled for 8 times continuously to obtain 8 samples. Every 2 samples produce one polarity and a combination of 4 polarities is unique for every phases. A minimum of 2 samples per polarity is needed to ease the phase detection. The demodulation process is done by comparing the combinational polarities with the look up table that represents the dibit. A real time simulation for the proposed design was successfully carried out using MATLAB Simulink software platform. In order to achieve the bit error rate (BER) of 10-6, at least 10 dB signal to noise ratio (SNR) is required in conventional design. However, the proposed technique can achieve the same BER value with only 5 dB SNR. Since some of power consuming elements such as voltage control oscillator (VCO), mixer and low pass filter (LPF) are no longer needed; the new QPSK demodulator will perform efficiently and consume almost 67% less operational power compared to conventional QPSK demodulator. Even though the proposed demodulator is neither coherent nor non-coherent, the results promised the possibility of a demodulator that is of less SNR requirement, less operating power and easily implementable.,Certification of Master's/Doctoral Thesis" is not available
Pages:	96
Call Number:	TK7872.M6A855 2013 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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