An innovative solution to design phase and quadrature pulsed coupled oscillators systems through electromagnetic waveguides is described in this paper. Each oscillator is constituted by an LC dif- ferential resonator refilled through a couple of current pulse generator circuits. The phase and quadrature coupling between the two differential oscillators is achieved using delayed replicas of generated fundamentals from a resonator as driving signal of pulse generator injecting in the other resonator. The delayed replicas are obtained by microstrip-based delay-lines. A 2.4 - 2.5 GHz VCO has been implemented in a 150 nm RF CMOS process. Simulations showed at 1 MHz offset a phase noise of −139.9 dBc/Hz and a FOM of −189.1 dB.
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the two resonators. The phase and quadrature oscillation of capacitances voltages is also reported in the figure. The evident presence of discontinuities on voltage waveforms induced by bias pulsed currents allows to verify that null projections correspond exactly to the pulses injected in relative resonators. We remark that maximum projection is 1/2 corresponding to the normal- ized noise charge injected onto the capacitor. Absence of any increase above value 1/2 of projection is the effect of the eigenvectors orthogonality.
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Abstract—A reduced complexity trellis-based turbo equalizer known as the in-phase (I)/quadrature-phase (Q) turbo equalizer (TEQ-IQ) invoking iterative channel impulse response (CIR) esti- mation is proposed. The underlying principle of TEQ-IQ is based on equalizing the I and Q component of the transmitted signal independently. This requires the equalization of a reduced set of separate I and Q signal components in comparison to all of the possible I/Q phasor combinations considered by the conventional trellis-based equalizer. It was observed that the TEQ-IQ operating in conjunction with iterative CIR estimation was capable of achieving the same performance as the full-complexity conven- tional turbo equalizer (TEQ-CT) benefiting from perfect CIR information for both 4- and 16-quadrature amplitude modulation (QAM) transmissions, while attaining a complexity reduction factor of 1.1 and 12.2, respectively. For 64-QAM, the TEQ-CT receiver was too complex to be investigated by simulation. How- ever, by assuming that only two turbo equalization iterations were required, which is the lowest possible number of iterations, the complexity of the TEQ-IQ was estimated to be a factor of 51.5 lower than that of the TEQ-CT. Furthermore, at BER = 10 3 the performance of the TEQ-IQ 64-QAM receiver using iterative CIR estimation was only 1.5 dB away from the associated decoding performance curve of the nondispersive Gaussian channel.
Quadrature branch-line hybrids are passive components widely used at microwave frequencies to design transmitting and receiving systems. These devices can be realized by using either waveguide or planar technology. In the latter case branch-line hybrids can be very small compared to their waveguide equivalents. In general, good performance and the required 90 ◦ phase response are normally achieved only within
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Abstract—In this paper, a broadband quadrature hybrid is presented. The hybrid comprises a Wilkinson divider, followed by an improved Schiffman phase shifter. An improved wideband Schiffman phase shifter on a single layer printed circuit board is accompanied by a lumped capacitor between two coupled lines. Lumped capacitor is in parallel with the odd-mode capacitance of the two coupled lines, hence, the odd-mode capacitance is increased and consequently the odd-mode impedance is decreased. Therefore, by this method we can control the ratio of the even mode impedance to the odd mode impedance which is critical in Schiffman phase shifter design. Compared with the cascading Microstrip multisection coupled lines, our proposed single layer phase shifter is smaller in size. Also, the proposed phase shifter has the greater bandwidth compared to the patterned ground plane Schiffman phase shifter and its realization is simpler because of its single layer structure. As an example, a Schiffman phase shifter at frequency f 0 = 650 MHz is designed and simulated. With the
We introduce a 16-dimensional constant-amplitude constellation that is generated by concatenating either four constant envelope quadrature-quadrature phase shift keying (CEQ 2 PSK) symbols from Saha and Birdsall or four CEQ 2 PSK symbols recently discovered by Cartwright and also introduced here. Our new constellation doubles the number of points available for data transmission without decreasing the distance between points or increasing energy, and may therefore be used in a trellis coded modulation (TCM) system without constellation expansion penalty. Because the new constellation has constant envelope, the modulation scheme becomes very attractive for nonlinear channels such as the magnetic recording channel or the satellite channel with traveling wave tube amplifiers.
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SK system. Specifically, Douillard et al.  demonstrated that the turbo equalizer was capable of mitigating the ef- fects of Inter-Symbol Interference (ISI), when performing channel equalization and channel decoding jointly and it- eratively. The advantages of performing the equalization and decoding jointly were further highlighted by Knicken- berg et al. , who proposed a non-iterative joint equaliza- tion and decoding technique based on a supertrellis struc- ture. This technique yielded an optimum performance, but it was restricted to incorporating simple interleavers due to the high complexity incurred by large interleaver arrays. Early turbo equalization investigations using the conven- tional trellis-based equalizer (CT-EQ) were constrained to applying Binary Phase Shift Keying (BPSK) and Quadra- ture Phase Shift Keying (QPSK) modulation schemes  and to limited Channel Impulse Response (CIR) durations, since the computational complexity incurred by the CT-EQ is dependent on both the maximum CIR duration and on the modulation mode utilised. Hence, turbo equalization research has been focused on developing reduced complex- ity equalizers, such as the low-complexity linear equalizer proposed by Glavieux et al. , the reduced complexity In- phase/Quadrature-phase Equalizer (I/Q-EQ)  and the Ra- dial Basis Function (RBF) equalizer advocated by Yee et al. .
states that for the setup shown in Fig. 3, the optimal pure single mode input state over all phase estimators is the squeezed vacuum. Our ﬁndings therefore suggest that for more general multimode input states the squeezed vacuum ceases to be opti- mal, or that estimators beyond the difference in output photon numbers must be considered. As such, our results not only illustrate how vibrational environments can give rise to enhanced quadrature squeezing in resonance ﬂ uorescence, but also moti- vate future studies analysing the performance of generalised non- Gaussian multimode states in interferometry.
IJEDR1602378 International Journal of Engineering Development and Research (www.ijedr.org) 2153 Abstract - In this document, a CMOS current-mode four-phase quadrature oscillator by means of current differencing transconductance amplifier (CDTA) that is based upon the pioneering first-order allpass filter is projected. The anticipated circuit configuration defines a very simple structure. It contains simply one resistor, two capacitors and three CDTAs. It is capable of affording four quadrature current outputs, and the stable affirm oscillation is also achieved subsequently to fewer than 1μs. Additionally, as the entire output impedances of the four-phase quadrature oscillator are high, the proposed oscillator circuit can be connected directly to the subsequent stage without any impedance identical necessities. PSPICE simulation results are included to substantiate the supposition.
vieux et al. , the Radial Basis Function (RBF) equaliser advocated by Yee et al.  and the In-phase/Quadrature- phase turbo equaliser (I/Q-TEQ) introduced by Yeap [9, 8]. Motivated by these trends, in this contribution we pro- posed a novel reduced complexity RBF channel equaliser based on the I/Q concept  which is referred to as the In- phase/Quadrature-phase RBF Equaliser (I/Q-RBF-EQ) for full response systems.
fact, at resonance frequency resonators do not introduce large phase shifts and energy refill process may produce sensible changes in the nominal period of oscillation. A pulsed current architecture, with pulses placed close to the maximum of the oscillation voltage, may result in the reduction of this phenomenon. Benefits of this architec- ture can be compared with results of other techniques recently proposed for the shaping/filtering of bias currents in single VCO [6,7] or with several quadrature oscillators architectures , however we remark our approach is based directly on system’s Floquet eigenvectors.
Chapter 5 clarifies how digital signal processing aides signal modulation implementation, and describes the architectural changes that lead to software defined radio. There is a brief mention of the requirements for real-time DSP, which includes several industrial tradeoffs that motivate the functionality of these processors. Chapter 6 describes a Matlab ® simulated implementation of QPSK, carefully noting simplifications and QPSK transmitter details. It concludes with complicated receiver details, including demodulation, a matched filter, automatic gain control, phase de-rotation, and symbol synchronization.
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In this paper, a theoretical assessment for the carrier phase recovery in the quadrature phase shift keying (QPSK) coherent optical transmission systems using the one-tap normalized LMS equalizer is discussed in detail. The analytical expression for this one-tap normalized LMS equalization has been presented in order to predict the bit-error-rate (BER) performance, e.g. the BER floor, in the carrier phase recovery process. It can be found that compared to the traditional differential carrier phase recovery, the one-tap normalized LMS equalization shows a similar performance for compensating the laser phase noise. The close-form prediction for the BER floor in the one-tap normalized LMS CPE algorithm gives the same expression as the differential carrier phase recovery.
The OFDM modulation uses orthogonal frequency subcarriers to transfer data and boot con fine image blur, which is essentially a low pass filter, to an arm and a leg frequency components one that low frequency data bits are transmitted intact. This approach requires high phase coherency to recognize the data bits correctly. The current study extends this idea on additional modifications on the modulation scheme in a way to mitigate LCD - camera relative movements from one end to the other the nab of a single frame, which results in outline blur it form ion on the captured images . This kind of distortions would be studied later seriously degrades the performance of Quadrature Phase Shift Keying (QPSK) modulated OFDM signals.
Abstract — Modeling and analysis of AVR, PSS and UPFC in SMIB system for the transient stability enhancement and improvement of power transfer capability have been done in this paper. The effects of UPFC, AVR and PSS controller evaluated under different case studies, namely by step changing reference voltage, infinity bus voltage, mechanical torque and introducing short circuit fault into the system has been made. In all cases the response of rotor angle, slip, excitation voltage, and electrical torque were simulated. The control strategies of UPFC are in phase voltage control, quadrature voltage control, quadrature current control, real current control and phase angle control, but in this paper except phase angle control the leftovers were implemented.
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Hybrid couplers are the special case of a four-port directional coupler that is designed for a 3-dB (equal) power split . Hybrids couplers are of two types, 90 degree or quadrature hybrids and 180 degree hybrids. In this proposed VM circuit 90 degree hybrid couplers are considered. The basic configuration of a 90 degree hybrid coupler has two cross-over transmission lines over a length of quarter wavelength, corresponding with the center frequency of operation.
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A comparative study have been done of digital modulation techniques used in wireless communication system. The simulation model and the output waveform of the different digital modulation techniques have been discussed in this paper. Hence this paper emphasises on a comparative modulation techniques i.e. Amplitude shift keying(ASK),quadrature phase shift keying(QPSK),binary phase shift keying(BPSK),frequency shift keying(FSK),on- off keying(OOK).
Abstract: With the growing demand in modern communication, it has become necessary to give better and efficient service to users by using better technique. Technique such as Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), Phase Shift Keying (PSK), Differential Phase shift Keying (DPSK) and Quadrature Amplitude Modulation (QAM) are very important parts of the implementation of modern communications systems in which DPSK is the simplest and most robust of all techniques. In this paper, evaluation of SNR in terms of constant bit error rate is performed on AWGN, Rayleigh and Rician fading channels. Among these channels, Rician is showing better performance as compared to AWGN and Rayleigh.
Recently, higher order modulation formats are broadly studied for long haul optical communication systems. These high order modulation formats include quadrature phase shift keying (QPSK), quadrature amplitude modulation (QAM), and orthogonal frequency division multiplexing (OFDM) with coherent detection and digital signaling processing (DSP) algorithm (Tao et al., 2013). For external modulation, IQ modulator is normally utilized at the transmitter, and optical hybrid and local oscillators together with DSP algorithms at the receiver. These sources are implemented by using application-specific integrated circuits (ASICs) for signal detection.
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In this paper we evaluate the performance of ½ rate convolution coding with different modulation techniques such as Binary phase shift keying (BPSK), Quadrature phase shift keying (QPSK) and Quadrature amplitude modulation (QAM- 16) for direct sequence code division multiple access(DS- CDMA) system using maximal ratio combining (MRC) and equal gain combining (EGC) diversity techniques over Rician fading channel. The performance of ½ rate convolution coding with different modulation techniques are analyzed in terms of Bit error rate (BER) and Signal to noise ratio (SNR). Based on simulation results we have concluded that we obtain better gain in SNR performance when ½ rate convolution coding is used with different modulation techniques.