Showing papers on "Demodulation published in 2012"

Design of a High-Data-Rate Differential Chaos-Shift Keying System

Abstract: In a differential chaos-shift keying (DCSK) system, the reference and information chaotic bearing signals are transmitted in two consecutive time slots and require the presence of delay components in the modulator and demodulator circuits. This system design requires a difficult-to-implement radio-frequency delay line that limits the data rate. The code-shifted DCSK (CS-DCSK) system proposes a solution for these problems by spreading the two chaotic slots by Walsh codes instead of using a time delay and sending them during the same time interval. In this brief, we extend the study of the CS-DCSK system, and we design two versions of a high-data-rate CS-DCSK system, which increase the data rate and can also perform in a multiuser case. The idea to achieve a high data rate is to get the information bits to share the same reference chaotic slot, where their separation is assured and maintained by different chaotic signals. In addition, this new design is not limited to a restricted number of Walsh codes such as CS-DCSK and provides from the properties of the chaotic signal in terms of security and good correlation properties. Finally, the performances of the systems are analyzed.

Diagnosis of Three-Phase Electrical Machines Using Multidimensional Demodulation Techniques

Abstract: This paper deals with the diagnosis of three-phase electrical machines and focuses on failures that lead to stator-current modulation. To detect a failure, we propose a new method based on stator-current demodulation. By exploiting the configuration of three-phase machines, we demonstrate that the demodulation can be efficiently performed with low-complexity multidimensional transforms such as the Concordia transform (CT) or the principal component analysis (PCA). From a practical point of view, we also prove that PCA-based demodulation is more attractive than CT. After demodulation, we propose two statistical criteria aiming at measuring the failure severity from the demodulated signals. Simulations and experimental results highlight the good performance of the proposed approach for condition monitoring.

Receiver, transmitter and radio communication method

Abstract: A mobile station includes: a physical channel segmentation unit to receive radio signals including multiple orthogonal signals which are orthogonal to each other, and multiple non-orthogonal signals which are not orthogonal to each other; and data demodulating/decoding units to extract the non-orthogonal signal addressed to the mobile station from the multiple non-orthogonal signals by demodulating and cancelling the radio signal addressed to another mobile station by use of the orthogonal signals included in the radio signals received by the physical channel segmentation unit, and demodulate the signal included in the orthogonal signals and addressed to the mobile station, and the extracted non-orthogonal signal addressed to the mobile station.

Optical codeword demodulation with error rates below the standard quantum limit using a conditional nulling receiver

Abstract: Researchers experimentally demonstrate the first joint-detection receiver capable of performing a joint measurement over pulse-position-modulation codewords. This result — the largest improvement over the standard quantum limit reported to date — is accomplished by using a conditional nulling receiver, which uses optimized-amplitude coherent pulse nulling, single-photon detection and quantum feedforward.

Sensorless starting of a wound-field synchronous starter/generator for aerospace applications

Abstract: The present paper describes an angle and speed estimation algorithm suitable for the control of a wound-field synchronous starter/generator (S/G) without position sensors for aircraft engine starting applications. The proposed control strategy is based on the injection of a high-frequency voltage signal and the subsequent demodulation of the resulting high-frequency stator current components. The coupling due to high-speed operation that degrades the estimation accuracy of similar algorithms based on signal injection is taken into account. Modeling of the machine response to a high-frequency voltage signal injected into the estimated d-axis is presented, also considering the influence of damping circuits both on the d- and q-axis. Local asymptotic stability of the proposed observer is also demonstrated. Through extensive experimental results, the proposed control technique is shown capable of guaranteeing full-torque sensorless operation at zero speed and sustained operation up to engine ignition speed.

Portable Real-Time Microwave Camera at 24 GHz

Abstract: This paper presents a microwave camera built upon a two-dimensional array of switchable slot antennas. The camera borrows from modulated scattering techniques to improve isolation among the array elements. The camera was designed to measure vector electric field distribution, be compact, portable, battery operated, possess high dynamic range, and be capable of producing real-time images at video frame-rate. This imaging system utilizes PIN diode-loaded resonant elliptical slot antennas as its array elements integrated in a simple and relatively low-loss waveguide network thus reducing the complexity, cost and size of the array. The sensitivity and dynamic range of this system is improved by utilizing a custom-designed heterodyne receiver and matched filter for demodulation. The performance of the multiplexing scheme, noise-floor and dynamic range of the receivers are presented as well. Sources of errors such as mutual-coupling and array response dispersion are also investigated. Finally, utilizing this imaging system for various applications such as 2-D electric field mapping, and nondestructive testing is demonstrated.

Dynamic multidimensional optical networking based on spatial and spectral processing

Abstract: An optical network includes a multidimensional coder and modulator for handling multiple-in-multiple-out MIMO spatial lightpath properties and content of any specific supercarrier, a spatial mode multiplexer responsive to orthogonal frequency division multiplexing OFDM transmissions and the multidimensional coder, a spatial-spectral routing node coupled over a fiber link to the spatial mode multiplexer for performing switching granularity by a spatial mode reconnection, a multidimensional decoder and demodulator; and a spatial mode demultiplexer coupled over a fiber link to the spatial-spectral routing node and responsive to the multidimensional decoder and demodulator.

25 Gbit/s QPSK Hybrid Fiber-Wireless Transmission in the W-Band (75–110 GHz) With Remote Antenna Unit for In-Building Wireless Networks

Abstract: In this paper, we demonstrate a photonic up-converted 25 Gbit/s fiber-wireless quadrature phase shift-keying (QPSK) data transmission link at the W-band (75-110 GHz). By launching two free-running lasers spaced at 87.5 GHz into a standard single-mode fiber (SSMF) at the central office, a W-band radio-over-fiber (RoF) signal is generated and distributed to the remote antenna unit (RAU). One laser carries 12.5 Gbaud optical baseband QPSK data, and the other acts as a carrier frequency generating laser. The two signals are heterodyne mixed at a photodetector in the RAU, and the baseband QPSK signal is transparently up-converted to the W-band. After the wireless transmission, the received signal is first down-converted to an intermediate frequency (IF) at 13.5 GHz at an electrical balanced mixer before being sampled and converted to the digital domain. A digital-signal-processing (DSP)-based receiver is employed for offline digital down-conversion and signal demodulation. We successfully demonstrate a 25 Gbit/s QPSK wireless data transmission link over a 22.8 km SSMF plus up to 2.13 m air distance with a bit-error-rate performance below the 2 × 10-3 forward error correction (FEC) limit. The proposed system may have the potential for the integration of the in-building wireless networks with the fiber access networks, e.g., fiber-to-the-building (FTTB).

Apparatus, system, and method for back-channel communication in an inductive wireless power transfer system

Abstract: An inductive wireless power transfer device comprises a transmitter that comprises a transmit coil configured to generate a wireless power signal to a coupling region in response to an input voltage, and a modulator configured to modulate the wireless power signal and encode data with the wireless power signal to establish a back-channel communication link from the transmitter to a receiver. An inductive wireless power receiving device comprises a receiver that comprises a receive coil configured to generate a time varying signal in response to receiving a modulated wireless power signal from a transmitter in a coupling region, and a demodulator configured to demodulate the modulated wireless power signal from an established back-channel communication link from the transmitter to a receiver. Related inductive wireless power transfer systems and methods for back-channel communication from the transmitter to the receiver of an inductive wireless power transfer system are disclosed.

Analysis of Modulated Multivariate Oscillations

Abstract: The concept of a common modulated oscillation spanning multiple time series is formalized, a method for the recovery of such a signal from potentially noisy observations is proposed, and the time-varying bias properties of the recovery method are derived. The method, an extension of wavelet ridge analysis to the multivariate case, identifies the common oscillation by seeking, at each point in time, a frequency for which a bandpassed version of the signal obtains a local maximum in power. The lowest-order bias is shown to involve a quantity, termed the instantaneous curvature, which measures the strength of local quadratic modulation of the signal after demodulation by the common oscillation frequency. The bias can be made to be small if the analysis filter, or wavelet, can be chosen such that the signal's instantaneous curvature changes little over the filter time scale. An application is presented to the detection of vortex motions in a set of freely drifting oceanographic instruments tracking the ocean currents.

Evolution of reference signals for LTE-advanced systems

Abstract: 3GPP LTE Release 10 standards (also known as LTE-Advanced) adopted some of the state-of-the-art radio access technologies that include carrier aggregation, eight-layer downlink spatial multiplexing, and four-layer uplink spatial multiplexing. For facilitating these enhancements, reference signals have significantly evolved in LTE-Advanced. This article examines underlying design principles of the LTE-Advanced reference signals. Specifically, newly introduced dedicated demodulation reference signals and channel state information reference signals for downlink and improvements of demodulation reference signals and sounding reference signals in uplink are discussed.

Remote Sensing of Vital Signs Using a Doppler Radar and Diversity to Overcome Null Detection

Abstract: Vital signs detection by means of several topologies based on Doppler radar are proposed in this paper with the aim of overcoming the problem of null detection. They are based on phase and frequency diversity. The proposed topologies are an alternative to I/Q demodulation and double-sideband transmission. Four topologies are proposed, three of them based on phase diversity and one based on frequency diversity. The first topology is based on using two phase-shifted receivers. The second one is based on a physical antenna displacement between two receivers. A third system with a dynamic phase variation is also presented, which permits to work with only one receiver. The last topology is a radar with frequency diversity within the 2.4 GHz ISM band, which permits a dynamic change of the frequency dynamically in order to place the receiver always in a maximum. A system to empirically characterize nulls is also developed to validate the proposed topologies.

Two-step phase demodulation algorithm based on the extreme value of interference.

Abstract: Using the maximum and the minimum of interference, a novel two-step phase demodulation algorithm is proposed to perform the phase extraction in phase-shifting interferometry. By means of the simulation calculation and the experimental research, it is proved that both the measured phase and the phase shift with high precision can be obtained in the proposed algorithm.

Design and Exploration of Low-Power Analog to Information Conversion Based on Compressed Sensing

Abstract: The long-standing analog-to-digital conversion paradigm based on Shannon/Nyquist sampling has been challenged lately, mostly in situations such as radar and communication signal processing where signal bandwidth is so large that sampling architectures constraints are simply not manageable. Compressed sensing (CS) is a new emerging signal acquisition/compression paradigm that offers a striking alternative to traditional signal acquisition. Interestingly, by merging the sampling and compression steps, CS also removes a large part of the digital architecture and might thus considerably simplify analog-to-information (A2I) conversion devices. This so-called “analog CS,” where compression occurs directly in the analog sensor readout electronics prior to analog-to-digital conversion, could thus be of great importance for applications where bandwidth is moderate, but computationally complex, and power resources are severely constrained. In our previous work (Mamaghanian, 2011), we quantified and validated the potential of digital CS systems for real-time and energy-efficient electrocardiogram compression on resource-constrained sensing platforms. In this paper, we review the state-of-the-art implementations of CS-based signal acquisition systems and perform a complete system-level analysis for each implementation to highlight their strengths and weaknesses regarding implementation complexity, performance and power consumption. Then, we introduce the spread spectrum random modulator pre-integrator (SRMPI), which is a new design and implementation of a CS-based A2I read-out system that uses spread spectrum techniques prior to random modulation in order to produce the low rate set of digital samples. Finally, we experimentally built an SRMPI prototype to compare it with state-of-the-art CS-based signal acquisition systems, focusing on critical system design parameters and constraints, and show that this new proposed architecture offers a compelling alternative, in particular for low power and computationally-constrained embedded systems.

Apparatus and method for calibration of supply modulation in transmitter

Abstract: A transmit apparatus having a supply modulator is provided. The apparatus includes a detector and the supply modulator. In the method, the detector detects an output signal of the supply modulator. Also, the supply modulator receives the detected output signal of the supply modulator from the detector and calibrates a modulation characteristic of the supply modulator. The transmit apparatus having a supply modulator includes a modulator/demodulator (modem) and the supply modulator. The modem provides a calibration signal for calibrating a modulation characteristic of the supply modulator, to the supply modulator. The supply modulator outputs a modulated signal in accordance with the calibrated modulation characteristic of the supply modulator based on the calibration signal from the modem.

Optical and millimeter-wave radio seamless MIMO transmission based on a radio over fiber technology

Abstract: Multi-input multi-output (MIMO) transmission of two millimeter-wave radio signals seamlessly converted from polarization-division-multiplexed quadrature-phase-shift-keying optical signals is successfully demonstrated, where a radio access unit basically consisting of only optical-to-electrical converters and a radio receiver performs total signal equalization of both the optical and the radio paths and demodulation with digital signal processing (DSP). Orthogonally polarized optical components that are directly converted to two-channel radio components can be demultiplexed and demodulated with high-speed DSP as in optical digital coherent detection. 20-Gbaud optical and radio seamless MIMO transmission provides a total capacity of 74.4 Gb/s with a forward error correction overhead of 7%.

Partial FFT Demodulation: A Detection Method for Highly Doppler Distorted OFDM Systems

Abstract: Employing Orthogonal Frequency Division Multiplexing (OFDM) signaling over time-varying channels results in inter-carrier interference (ICI) and degraded detection error probability due to the loss of orthogonality among the subcarriers This problem is particularly exacerbated for systems operating in highly mobile scenarios such as underwater acoustic (UWA) communications, digital video broadcasting (DVB) for mobile devices and vehicle-to-vehicle (V2V) networks To address the problem of data detection in such scenarios, we propose a novel demodulation strategy using several partial interval Fast Fourier Transforms (FFTs) instead of a conventional, single full interval FFT Algorithms for computing the weights used to combine the outputs of the partial FFT are presented for three scenarios: full, partial and no knowledge of the time varying channel Numerical simulations and an approximate theoretical analysis show that significant performance gains can be obtained over traditional equalizers at a very moderate complexity

Intelligent device system and method for distribution of digital signals on a wideband signal distribution system

Abstract: A plurality of intelligent device systems for use with a wideband signal distribution network, and methods for transmitting digital information and receiving digital and non-digital information onto and off of an RF carrier through a wideband signal distribution network, are disclosed. The intelligent device systems provide networks of intelligent devices that modulate and demodulate digital video, IP video/data/voice and digital wireless onto, and off of, a wideband signal distribution system, such as an analog carrier system, using existing EIA/TIA 568 standard wiring infrastructure. The methods modulate and demodulate digital video, IP video/data/voice and digital wireless onto, and off of, a wideband distribution system, such as an analog carrier system, and separate IP portions from non-IP portions.

Method and apparatus for multiple-input multiple-output operation

Abstract: A wireless transmit/receive unit (WTRU) receives a downlink transmission from an eNodeB including a plurality of spatial layers transmitted to a plurality of WTRUs paired for multi-user MIMO. The WTRU decodes the downlink transmission based on a corresponding WTRU-specific reference signal. WTRU-specific reference signals are multiplexed using a frequency and code division multiplexing. WTRU-specific reference signals for different sub-group of antenna ports are multiplexed onto different subcarriers in a frequency domain and the WTRU-specific reference signals of the same sub-group of antennas ports are multiplied by an orthogonal cover code. The resource elements used for the WTRU-specific reference signals on antenna ports in one sub-group may be muted on antenna ports in another sub-group. A WTRU may transmit the uplink demodulation reference signal without precoding. The number of resource blocks allocated for the demodulation reference signal may be greater than the number of resource blocks allocated for the payload.

Ambiguity Suppression by Azimuth Phase Coding in Multichannel SAR Systems

Abstract: The current generation of spaceborne synthetic aperture radar (SAR) systems suffers from a tradeoff between the achievable spatial resolution and swath width. This has motivated intensive research both on more flexible SAR systems, using multiple transmit/receive channels, and on techniques for removing the ambiguities. Among these techniques, the azimuth phase coding (APC), recently proposed to suppress range ambiguities in conventional SAR systems, stands out for its negligible implementation complexity and its effectiveness for point and distributed ambiguities. This paper investigates the possibility of applying the APC technique to the new, forthcoming generation of multichannel SAR systems, based on digital beamforming on receive. The extension of APC to multichannel SAR systems is mathematically described. Specific merit figures are defined to quantify the APC performance. A numerical analysis is developed to characterize the influence on the APC behaviors of the main SAR system parameters. Finally, an example of APC performance is provided, by considering two multichannel SAR systems based on a planar and a reflector antenna.

Inter-vehicle alert system with nagable video look ahead

Abstract: An apparatus includes a video encoder, a camera and radio frequency modulation circuitry. The radio frequency modulation circuitry is operative to modulate a radar signal to include video data. A radar transmitter is operatively coupled to the radio frequency modulation circuitry, and is operative to transmit a radar signal including the video data. The apparatus may also include radio frequency demodulation circuitry and a video decoder. The video decoder is operative to decode video data contained in a radar signal demodulated by the radio frequency demodulation circuitry. An inter-vehicle alert system controls the camera to initiate capturing video data which includes the video data. A method of operation modulates a radar signal to include at least a portion of the video data captured in response to detecting an obstruction, and transmits the radar signal to a second vehicle via an antenna array oriented at the moving vehicle's rear.

Microwave spectral analysis based on photonic compressive sampling with random demodulation

Abstract: In this Letter, we present a photonic compressive sampling scheme based on optical sampling and random demodulation for microwave spectral analysis. A novel (to our knowledge) approach to realizing the multiplication of a pseudorandom binary sequence and the input microwave signal of interest in the optical domain is proposed, which largely simplifies the implementation of the compressive sampling. A spectrally sparse signal can be successfully captured by an electrical digitizer with a sampling rate much lower than the Nyquist rate with the help of random demodulation and the sparse reconstruction algorithm. Identification of the signals with multiple frequency components is successfully demonstrated.

Digital beamforming antenna and datalink array

Abstract: A method and system for beamforming a multi-element array using time delays is provided. The array includes transmit array elements and receive array elements. Each of the array elements includes a processor. Modulation and demodulation functions are performed at the processors of each array element. The modulation and demodulation functions utilize receive time offsets and phase shifts, and transmit time offsets and phase shifts, respectively. The receive time offsets and phase shifts, and the transmit time offsets and phase shifts are determined by a central processing unit in order to beam form received signals and transmitted signals, respectively. The array elements are arranged in a daisy chain fashion in order to facilitate communication of control parameters, communication of bits to be transmitted and distributed combining of demodulated baseband samples from one array element to another and communicating the combined samples to the central processing unit.

Review of Channel Estimation for Wireless Communication Systems

Abstract: Wireless communication systems have evolved over the ages. However, there are some undesirable effects of a wireless communication channel on the signals transmitted through it which are caused by the physical properties of the channel. These in turn always result in attenuation, distortion, delays, and phase shift of the signals arriving at the receiver end of the communication system. Consequently, there is a need to provide perfect and up-to-date estimate of the channel, in order to compensate for these effects, and for accurate signal demodulation, equalization, decoding, and a host of other baseband processing applications at the receiver end of the systems. In this article, a review of the various channel estimation techniques is provided. This review will be of assistance in reaching a compromised decision regarding channel estimation techniques to be employed in any wireless communication systems being developed.

Performance Analysis on Using Period-One Oscillation of Optically Injected Semiconductor Lasers for Radio-Over-Fiber Uplinks

Abstract: Nonlinear period-one (P1) dynamics of a semiconductor laser are investigated for radio-over-fiber uplink transmission. By optical injection locking, the laser in a base station is driven into the P1 oscillation state, which is further locked by the uplink microwave signal through modulation on the bias current. Due to double locking by both the optical injection and current modulation, the uplink microwave signal is converted into an optical signal for transmission to the central office. Comprehensive numerical simulations reveal that the proposed uplink transmission based on the P1 state provides wide, continuous, and optically-controlled tunability for the uplink subcarrier frequency, which exceeds the laser modulation bandwidth. The laser with a relaxation resonance frequency of only 10.25 GHz is shown to support subcarrier frequencies reaching 60 GHz. Compared to the commonly used stable injection locking state and the free-running state, the proposed P1 state generates the microwave oscillation by the inherent nonlinear dynamics and thus reduces the requirement on the uplink signal strength for low-error transmission. Both electrical demodulation and all-optical demodulation are investigated, where the latter is found to be better in terms of the immunity to dispersion and the speed requirement on optoelectronic conversion. The results illustrate the capability of using the P1 oscillation state for optically controlled uplink transmissions.

The color shift key modulation with non-uniform signaling for visible light communication

Abstract: Color shift key (CSK) modulation method is a new modulation method for visible light communication (VLC) system, which transmits information through the light's color property of a multi-color light source, typically a RGB LED. This paper analyzes the illumination and communication performances of CSK signals, including flicker effect, dimming range, color rendering index (CRI), luminous efficacy rate (LER), variable data rate and error probability, and also generates the optimized power weights combination group of the red, green and blue light emitted from a RGB LED, which meet the current illumination requirements, through a 2 level non-uniform signaling method, and analytical and simulation result shows a not good enough bit error rate (BER) performance. Maximum correlation coefficient and minimum RGB space distance demodulation methods with better BER performance are also discussed, simulation result shows a close relationship between the BER performance and both the entire valid CSK signals and demodulation method. Finally, a tradeoff of the CRI is discussed.