Carrier Recovery System Research Articles

OSNR and dispersion tolerance of FWM based optical carrier recovery scheme

In this paper we demonstrate the Optical signal-to-noise ratio (OSNR) and Dispersion characteristics of Four-Wave Mixing (FWM) based optical carrier recovery scheme for a 10-Gb/s nonreturn-to-zero binary phase-shift-keyed input. The performance was evaluated by measuring the linewidth of the recovered carrier against different OSNR and accumulated dispersion values and recording the eye diagrams. The system characterization will enable new avenues of using the FWM based carrier recovery system in phase-sensitive amplification and heterodyne detection.

PPLN-Based Low-Noise In-Line Phase Sensitive Amplifier with Highly Sensitive Carrier-Recovery System

PPLN-Based Low-Noise In-Line Phase Sensitive Amplifier with Highly Sensitive Carrier-Recovery System

Multiplier-Free Phase Recovery With Polar-domain Multisymbol-Delay-Detector

We present a highly efficient carrier phase recovery module for coherent optical detection of single-carrier advanced modulation formats with differential precoding. Remarkably, we eliminate all multipliers from the multisymbol-delay-detector (MSDD) carrier recovery system, without incurring performance penalty relative to the previously shown complex-domain MSDD. We also introduce a novel polyblock hardware parallelization method for the MSDD, eliminating the “distant feedback” parallelization penalty of decision-feedback-based carrier recovery methods, such as MSDD. Simulations indicate extremely high nonlinear phase noise tolerance for the new polar MSDD carrier recovery system for 16-QAM 2000 km transmission. The ultralow-complexity CR is simulated and electrically demonstrated in real-time at 25 Gbaud symbol rate over FPGA HW for single-carrier QPSK and 16-QAM constellations, respectively.

Novel carrier recovery scheme in multicarrier digital TV system

SUMMARYThis work is aimed at researching and analyzing the performance of carrier recovery (CR) with two transmit antennas on a multicarrier digital TV system operating in time‐selective fading channel. It is shown in the paper that CR can correct the performance degradation caused by Doppler effect when the terminal is receiving high resolution digital TV signals in a fast moving environment. To have the ability to cover a large frequency range, the CR system should do a frequency sweep first. Then the coarse and fine frequency offset estimation is introduced. Both the theoretical and simulated results give valuable insight that the CR is able to perform well with a certain amount of channel fading. The phase and noise effect on the CR performance is also studied. The CR system and the working procedure concerning CR and timing recovery are also researched to give a full solution on synchronization. Copyright © 2012 John Wiley & Sons, Ltd.

Design and Implementation of Experimental System for Comprehensive Utilization of Oil Shale

The single model of oil shale development, which is, burning in boiler for power generation and distillation for shale oil, may cause enormous waste of oil-gas resources and semi-coke. For energy conservation and efficiency improvement, it is necessary to realize the comprehensive utilization of oil shale. The development of experimental system is foundation of further studying. In the paper, an experimental system for comprehensive utilization of oil shale is designed and realized. These includes: spouted bed combustor and shale ash collection system, oil shale retort with solid heat carrier and shale oil recovery system. With the system, the realistic simulation under different condition such as different kinds of oil shale, operation condition can be studied. This work lays an experimental foundation for the further study of comprehensive utilization of oil shale.

Joint phase noise and frequency offset estimation and mitigation for optically coherent QAM based on adaptive multi-symbol delay detection (MSDD)

This paper extends our prior coherent MSDD Carrier Recovery system from QPSK to QAM operation and also characterizes for the first time the Carrier Frequency Offset (CFO) mitigation capabilities of the novel MSDD for QAM systems. We introduce and numerically investigate the performance of an improved MSDD carrier recovery system (differing from the one disclosed in our MSDD for QPSK prior paper), automatically adapting to the channel statistics for optimal phase-noise mitigation. Remarkably, we do not require a separate structure to estimate and mitigate CFO, but the same adaptive structure originally intended for phase noise mitigation is shown to also automatically provide frequency offset estimation and recovery functionality. The CFO capture range of our system is in principle infinite, whereas prior CFO mitigation systems have CFO capture ranges limited to a small a fraction of the baud-rate. When used for 16-QAM with coherent-grade lasers of 100 KHz linewidth, our MSDD system attains the best tradeoffs between performance and complexity, relative to other carrier recovery systems combining blind-phase-search with maximum likelihood detection. We also present additional MSDD phase-noise recovery system variants whereby substantially reduced complexity is traded off for slightly degraded performance. Our MSDD system is able to switch "on-the-fly" to various m-QAM constellation sizes, e.g. seamlessly transition between 16-QAM and QPSK, which may be useful for dynamically adaptive optical networks.

Demonstration and optimization of an optical impulse radio ultrawideband distribution system using a gain-switched laser transmitter

What we believe to be a novel system for the distribution of high-definition video streams in a residential environment is demonstrated. The system utilizes impulse radio ultrawideband (IR-UWB) technology integrated with a fiber-based distribution network. The pulses are directly generated in the optical domain, and the receiver is implemented with a carrier recovery system for the demodulation. The system was built and tested to demonstrate error-free operation of the distribution network and the receiver. Spectrum shaping by varying the pulse position within the bit slot to optimize system performance is also examined.

Performance Optimization of High Order QAM in Presence of Phase Noise and AWGN: Application to a Decision Directed Frequency Synchronization System

The paper presents an analysis of the impact of Local Oscillators (LO) phase noise on the performance of digital transmission systems. Using an efficient phase noise model, we study degradations induced by phase noise and Additive White Gaussian Noise (AWGN) on a carrier recovery system combined to high order Quadrature Amplitude Modulations (QAM). Simulation results show that an optimum trade-off between AWGN and phase noise robustness for the loop bandwidth can be determined. In order to compare simulated and analytical performance, a new general expression of the bit error probability is developped for square QAM in the presence of phase noise over Gaussian channel. Furthermore, novel decision areas related to Quadrature Amplitude Modulations are determined in order to improve the performance of the carrier recovery algorithm in the presence of phase noise and frequency offset.

BPSK to ASK Signal Conversion Using Injection-Locked Oscillators—Part I: Theory

This paper presents a new method and circuit for the conversion of binary phase-shift keying (BPSK) signals into amplitude shift keying signals. The basic principles of the conversion method are the superharmonic injection and locking of oscillator circuits, and interference phenomena. The first one is used to synchronize the oscillators, while the second is used to generate an amplitude interference pattern that reproduces the original phase modulation. When combined with an envelope detector, the proposed converter circuit allows the coherent demodulation of BPSK signals without need of any explicit carrier recovery system. The time response of the converter circuit to phase changes of the input signal, as well as the conversion limits, are discussed in detail.

Analysis of the Multimodulus Blind Equalization Algorithm in QAM Communication Systems

The constant modulus algorithm (CMA) for blind equalization requires a separate carrier-recovery system for phase recovery. This letter mathematically analyzes a modified CMA, called the multimodulus algorithm (MMA), which may perform joint blind equalization and carrier recovery without the need for a separate carrier-recovery system for quadrature amplitude modulation signal constellations. The analyses focus on five aspects of the MMA: 1) derivation of the general formulation of the MMA cost function; 2) stationary points of the MMA; 3) desired global minima of the MMA; 4) unstable equilibria (saddle points) of the MMA; and 5) analytic verification of a discrete-time first-order phase-locked loop hidden inside the MMA, which is absent from the conventional CMA. Analysis results indicate that the MMA alone may be able to remove intersymbol interference and simultaneously correct the phase error, because it implicitly incorporates a phase-tracking loop, which automatically recovers carrier phase.

Design optimization of a TDMA burst modem for small earth stations in a channel containing two nonlinear devices

AbstractThe conventional TDMA satellite communication system generally involves operations in which a sufficient amount of back‐off is provided by using a large‐scale high‐power amplifier (HPA) in the earth station. However, if the HPA in the earth station can be operated at the saturation point, the earth station can be downsized and rendered into a low‐power consumption station, with considerable benefits in terms of earth station installation and economy of operation. The authors have proposed a system combining an optimized transmission system and error‐correction code, using burst modem filters and other devices, in a transmission system including two nonlinear devices of an earth station HPA and a satellite traveling‐wave tube amplifier (TWTA), and have confirmed by computer simulations and experiments that it is feasible to operate the earth station HPA at its saturation point. The authors have also demonstrated that adequate performance characteristics can be attained in terms of burst‐to‐burst interference and cycle‐skipping characteristics in the carrier recovery system. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(8): 47–62, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10149

Convergence properties of optimal adaptive carrier phase jitter predictors for sinusoidal jitter

Carrier recovery systems in high performance digital modem receivers must remove carrier phase jitter as well as track carrier phase and frequency offsets. A popular approach to removing periodic phase jitter is to use an adaptive LMS FIR linear predictor with baud spaced taps to predict the jitter angle one baud in the future. Experimentally, the convergence rates for such predictors were found to depend heavily on the jitter frequency. It is well known in adaptive filter theory that the predictor convergence rate depends on the eigenvalues of the correlation matrix of the input signal. By allowing jitter predictors with a given number of taps to have tap spacings greater than one baud and by deriving a general formula for the eigenvalues of the appropriate correlation matrix, it is shown how to design predictors exhibiting optimal convergence rates over a range of commonly observed jitter frequencies.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An adaptive notch-filter-based frequency-difference detector and its applications

A frequency-difference detector (FDD) based on an adaptive notch filter is proposed. Frequency detectors are useful in decreasing acquisition times in phase-locked-loop and Costas-loop-based clock and carrier-recovery systems. To avoid certain drawbacks associated with signal down-conversion to baseband, the input is initially processed in the bandpass domain. In applications where limits on acquisition time demand a wide closed-loop tracking bandwidth, the output of the proposed FDD has less inherent ripple and bias when compared with a quadricorrelator, a commonly used FDD. Two applications of the proposed FDD in the demodulation of BPSK data are presented.

Design and experimental evaluation of a pilot tone aided carrier recovery system for wireless personal communications

Following a review of the design and construction of a prototype circuit for pilot tone aided carrier recovery, experimental test results are presented. These results demonstrate the circuit's ability to provide a feasible, reliable and economic solution for reference signal recovery. The many potential applications benefits of reference signal recovery include improved bit error rate performance for wireless modems. >

Adaptive carrier recovery systems for digital data communications receivers

Adaptive or predictive carrier recovery systems, which are essential in high-performance quadrature-amplitude-modulated (QAM) data communications systems to correct for phase jitter and frequency offset, are considered. Analytical and experimental results are presented for two structures that implement a predictive carrier recovery system. These systems, which adapt their structure to match the spectral properties of the impairments, avoid the conflict between a wide bandwidth (to track fast jitter) and a narrow bandwidth (to minimize output noise) inherent in most carrier recovery loops. Such a system increases the likelihood that very bandwidth-efficient modems (e.g., 7 b/s/Hz for 19.2 kb/s voiceband modem applications) can provide reliable transmission in the presence of severe phase jitter and frequency offset. In particular, the predictive carrier recovery systems can track sinusoidal jitter present at more than one frequency as well as generalized time-varying phase jitter processes. Both finite-impulse-response (FIR) and infinite-impulse-response (IIR) adaptive phase tracking systems are considered. Prior limitations on adaptive IIR filters are overcome by designing a structure that is guaranteed to be stable and to possess only a global minimum as the filter coefficients converge to their desired values. >

Modeling and performance of the North American Broadcast Teletext System with quasi-synchronous detection

In vestigial sideband systems the most critical region is the Nyquist region of the receiver response, which is difficult to control in practice, so that synchronous and quasi-synchronous detection are not perfect due to quadrature distortion. The advantages of phase-locked-loop quasi-synchronous detection and the factors influencing their design are discussed. These factors include incidental phase modulation introduced by the Nyquist slope of the receiver IF filter in response to synchronization signals, audio buzz, and the effects of other signal distortions. Analysis, modeling, and computer simulations have been used to study quasi-synchronous detection in Gaussian and impulse noise and multipath environments and to find carrier recovery phase error and teletext system performance curves. Possible improvements to television carrier recovery systems are suggested. It is concluded that well-designed quasi-synchronous carrier recovery loops suffer relatively minor degradations (about 0.5 dB) compared to narrowband (synchronous) carrier recovery, in multipath and noise environments of interest to broadcast teletext application.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A feedforward tracking filter. Part 2: Noise performance and applications

The performance of a Feedforward Tracking Filter (FTF) in the presence of white additive Gaussian noise is analysed. By studying the spectral properties and input-output signal-to-noise ratio (SNR), it is observed that the output of the nonlinear bandpass model of the FTF contains a mixture of signal and noise cross-modulation products. Due to the nonlinear effect, the FTF achieves tracking abilities at the expense of SNR. In addition, the probability density function of the phase error is evaluated. Finally, experimental results to verify the analysis and an application of the FTF to a fast carrier recovery system are presented.

Carrier Recovery Systems for Arbitrarily Mapped APK Signals

This paper introduces new carrier recovery techniques for general amplitude-phase keying (APK) modulation signals. The APK's include not only normal QAM but also arbitrarily mapped APK's, including an unsymmetrical APK. Difficulty in phase error detection due to signal mapping complexity, undesirable stable-lock point existence, and the contradiction between a fast acquisition and an accurate steady state performance can be overcome. For that purpose, an acquisition mode and a steady-state mode are used. Furthermore, read-only memories (ROM) are used for recognizing various system states. Random sampling controlled PLL noise performance and acquisition mode carrier recovery circuit pull-in performance with hysteresis property was obtained.

A New Carrier Recovery Technique for Vestigial-Sideband (VSB) Data Systems

In this concise paper we have developed a new carrier recovery system for vestigial sideband amplitude modulation (VSB-AM) data sets. Neither dc restoration nor extra bandwidth is required for the proposed system. A pilot tone is transmitted at the carrier frequency and the phase jitter is derived from the quadrature chnnnel. "Artificial" phase jitter which is introduced by the data signal can be eliminated by properly shaping the transmitted signal. We have also shown that even in the presence of channel distortion and white Gaussian noise, the proposed system can faithfully track up to 60-Hz phase jitter.

Carrier Phase-Jitter Extraction Method for VSB and SSB Data Transmission Systems

Theoretical analysis of the phase-jitter problem for a vestigial sideband (VSB) or single sideband (SSB) high-speed data transmission system is discussed in detail in this paper. Particular attention is paid to the effect of the phase shift introduced to the phase-jitter sideband components by various circuits in the carrier recovery system. Based on this theoretical analysis, a practical carrier recovery system, which will extract the phase jitter with minimum phase shift introduced to the phase-jitter sideband components, is proposed so that the overall effect of the phase jitter on the demodulated signal will be minimized.