4.4 Quadrature phase shift keying (QPSK) Quadrature phase shift keying (QPSK) has twice the bandwidth efficiency of BPSK since two bits are transmitted in a single modulation symbol. In the phase of the carrier takes on one of four equally spaced values‚ such as 0‚ π/2‚π and 3π/2‚ where each value of phase corresponds to a unique pair of message bits. The Quadrature phase shift keying (QPSK) signal for this set of symbol states may be defined as s_QPSK (t) =√(〖2E〗_s/T_s ) cos[〖2πf〗_c t +(i-1)π/2]
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The Communications Edge ™ Tech-note Author: Bob Watson FSK: Signals and Demodulation The most commonly used signal parameters for describing an FSK signal are shown in Figure 2. The minimum duration of a mark or space condition is called the element length. Typical values for element length are between 5 and 22 milliseconds‚ but element lengths of less than 1 microsecond and greater than 1 second have been used. Bandwidth constraints in telephone channels and signal propagation
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. . . . . . . . . Array geometry and element spacing . . . . . . . . . . . . . . . . . . . . . . . . 3 Channel Model 3.1 3.2 Mean Path Loss Fading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.1 3.2.2 Slow fading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fast fading . . . . . . .
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1. Explain what is meant by the term wireless. Wireless is a term used to describe telecommunications in which electromagnetic waves (rather than some form of wire) carry the signal over part or all of the communication path. 2. What is a frequency-shift-keying system? Describe two methods of generating FSK. Frequency-shift keying (FSK) is a method of transmitting digital signals. 6. Explain a method used to generate BPSK using Figure 10-5 as a basis. Need for modulation 1) to reduce the antenna
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Performance Analysis of DF Relay Systems with Keyhole and Correlation Effects Trung Q. Duong‚ Raj S. Mahat‚ and R. Dhakal Abstract—The main purpose of this paper is to derive closed form analytical expressions of symbol error rate (SER) of Mary phase shift keying (MPSK) for MIMO decode-and forward (DF) relay system. Based on moment generating function (MGF) of output symbol to noise ratio (SNR) of overall system SER is derived. In this paper‚ we consider an nt -antenna at the source S‚ an
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Shayla was sitting in the ferns close to Rayleigh. They both looked up between the leaves they caught a glimpse of something red. It has to be at the top of Castle Rock thought Rayleigh to herself. It was distant and unmenacing. She composed herself triumphantly‚ to hear the sounds of the hunt dying away‚ slowly. Yet no one made a sound; and as the minutes passed
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The Tyndall effect‚ also known as Tyndall scattering‚ is light scattering by particles in a colloid or particles in a fine suspension. It is named after the 19th-century physicist John Tyndall. It is similar to Rayleigh scattering‚ in that the intensity of the scattered light depends on the fourth power of the frequency‚ so blue light is scattered much more strongly than red light. An example in everyday life is the blue colour sometimes seen in the smoke emitted by motorcycles‚ in particular two-stroke machines
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GSM – Overview GSM is a globally accepted standard for digital cellular communications. What is GSM? If you are in Europe‚ Asia or Japan and using a mobile phone then most probably you must be using GSM technology in your mobile phone. GSM stands for Global System for Mobile Communication and is an open‚ digital cellular technology used for transmitting mobile voice and data services. The GSM emerged from the idea of cell-based mobile radio systems at Bell Laboratories in the early 1970s. The
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2002. [7] A. T. James‚ “Distributions of matrix variates and latent roots derived from normal samples‚” Annals of Mathematical Statistics‚‚ vol. 35‚ pp. 475–501‚ 1964. [8] G. J. Foschini and M. J. Gans‚ “On limits of wireless communications in a fading environment when using multiple antennas‚” Wireless Personal Communications‚ vol. 6‚ pp. 311–335‚ 1998. [9] S. M. Alamouti‚ “A simple transmit diversity technique for wireless communications‚” IEEE Journal on Select Areas in Communications‚ vol. 16
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me c2 !02 ! 2 2e 2 1 P = a = 3 3c 3 2 e me c2 3 eE0 sin(!t) RAYLEIGH SCATTERING At very low energy ! ⌧ !0 cross-section becomes: 8⇡ = 3 ✓ 2 e me c2 ◆2 ✓ ! !0 ◆4 Very strong depence on the frequency/wavelength shorter wavelengths are scattered most longer wavelengths travel in (almost) straight lines Rayleigh scattering experiment? 4 RAYLEIGH SCATTERING Why is the sky blue? The blue color of the sky is due to Rayleigh scattering. As light moves through the atmosphere‚ most of the longer
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