Showing papers on "Demodulation published in 2011"

Xampling: Signal Acquisition and Processing in Union of Subspaces

Abstract: We introduce Xampling, a unified framework for signal acquisition and processing of signals in a union of subspaces. The main functions of this framework are two: Analog compression that narrows down the input bandwidth prior to sampling with commercial devices followed by a nonlinear algorithm that detects the input subspace prior to conventional signal processing. A representative union model of spectrally sparse signals serves as a test-case to study these Xampling functions. We adopt three metrics for the choice of analog compression: robustness to model mismatch, required hardware accuracy, and software complexities. We conduct a comprehensive comparison between two sub-Nyquist acquisition strategies for spectrally sparse signals, the random demodulator and the modulated wideband converter (MWC), in terms of these metrics and draw operative conclusions regarding the choice of analog compression. We then address lowrate signal processing and develop an algorithm for that purpose that enables convenient signal processing at sub-Nyquist rates from samples obtained by the MWC. We conclude by showing that a variety of other sampling approaches for different union classes fit nicely into our framework.

Method and apparatus for reducing coupling between signals in a measurement system

Abstract: A method and an apparatus for separating a composite signal into a plurality of signals is described. A signal processor receives a composite signal and separates a composite signal in to separate output signals. Pre-demodulation signal values are used to adjust the demodulation scheme.

40 Gb/s W-band (75–110 GHz) 16-QAM radio-over-fiber signal generation and its wireless transmission

Abstract: The generation of a 40-Gb/s 16-QAM radio-over-fiber (RoF) signal and its demodulation of the wireless signal transmitted over free space of 30 mm in W-band (75-110 GHz) is demonstrated. The 16-QAM signal is generated by a coherent polarization synthesis method using a dual-polarization QPSK modulator. A combination of the simple RoF generation and the versatile digital receiver technique is suitable for the proposed coherent optical/wireless seamless network.

Signal transmission apparatus, electronic device, and signal transmission method

Abstract: A signal transmission apparatus including: a plurality of modulating sections configured to modulate a transmission object signal; and a plurality of demodulating sections configured to demodulate the modulated signals modulated by the modulating sections, wherein each of carrier frequencies as frequencies different from each other used by respective sets of the modulating sections and the demodulating sections is set such that frequency of a third-order intermodulation distortion component generated on a basis of two carrier frequencies adjacent to each other is not present within any of reception bands of modulated signals based on each of the other carrier frequencies.

Device and Method for the Demodulation of Modulated Electromagnetic Wave Fields

Abstract: A new pixel in semiconductor technology comprises a photo-sensitive detection region (1) for converting an electromagnetic wave field into an electric signal of flowing charges, a separated demodulation region (2) with at least two output nodes (D10, D20) and means (IG10, DG10, IG20, DG20) for sampling the charge-current signal at at least two different time intervals within a modulation period. A contact node (K2) links the detection region (1) to the demodulation region (2). A drift field accomplishes the transfer of the electric signal of flowing charges from the detection region to the contact node. The electric signal of flowing charges is then transferred from the contact node (K2) during each of the two time intervals to the two output nodes allocated to the respective time interval. The separation of the demodulation and the detection regions provides a pixel capable of demodulating electromagnetic wave field at high speed and with high sensitivity.

A 0.24-nJ/b Wireless Body-Area-Network Transceiver With Scalable Double-FSK Modulation

Abstract: An energy-efficient wireless body-area-network (WBAN) transceiver is implemented in 0.18-μm CMOS technology with 1-V supply voltage. For the low energy consumption, the body channel communication (BCC) PHY is utilized with the theoretical results of Maxwell's equation analysis behind the BCC. Based on the channel analysis, the resonance matching (RM) and contact impedance sensing (CIS) techniques are proposed to enhance the quality of the body channel. A double-FSK modulation scheme is adopted with high scalability to fulfill the IEEE 802.15.6 Task Group specifications. In addition, a low-power double-FSK transceiver is implemented by five circuit techniques: 1) a reconfigurable LNA with CIS; 2) a current-reuse wideband demodulator; 3) a divider-based local oscillator (LO) generation with duty-cycle correction in the receiver; 4) a reconfigurable driver with RM; and 5) a divider-based digital double-FSK modulator in the transmitter. As a result, fully WBAN compatible receiver and transmitter consume 2.4 and 2 mW, respectively, at a data rate of 10 Mb/s, corresponding to energy consumption of 0.24 nJ per received bit and 0.2 nJ per transmitted bit.

Long-Haul Analog Photonics

Abstract: A paper on long-haul analog photonics is presented using theory and experimental results. Various analog fiber-optic modulation formats are reviewed, including intensity modulation with direct detection, phase modulation with interferometric demodulation, and suppressed-carried techniques. Modulation linearization methods are reviewed. The limitations of and requirements for photodiode detectors are described.

Broadband wireless communications on high speed trains

Abstract: This tutorial paper provides a comprehensive overview on the recent development in broadband wireless communications for high speed trains. Starting with the introduction of the two-hop network structure, radio-over-fiber (RoF) based cell planning is described in detail. Moreover, based on the analysis of differences between conventional cellular systems and the one for high speed trains, promising techniques are recommended to improve the performance of handover, which is one of the main challenges in high speed train communications. Finally, in order to combat the fast fading caused by the high mobility, robust algorithms are needed in physical layer signal processing, including synchronization, channel estimation, modulation/demodulation, and so on.

Semiconductor device and driving method thereof

Abstract: The invention provides a semiconductor device with high yield by reducing an effect of variations in characteristics of a semiconductor element. Further, by reducing an effect of variations in characteristics of a semiconductor element to improve productivity, an inexpensive semiconductor device can be provided. Further, an inexpensive semiconductor device can be provided by forming a semiconductor device in a large amount over a large substrate such as a glass substrate and a flexible substrate. A semiconductor device of the invention includes a demodulation signal generating circuit and an antenna or a wire for connecting the antenna. The demodulation signal generating circuit includes a demodulation circuit and a correction circuit. The correction circuit corrects a first demodulation signal generated from the demodulation circuit and generates a second demodulation signal.

Single-chip multi-stimulus sensor controller

Abstract: A multi-stimulus controller for a multi-touch sensor is formed on a single integrated circuit (single-chip). The multi-stimulus controller includes a transmit oscillator, a transmit signal section that generates a plurality of drive signals based on a frequency of the transmit oscillator, a plurality of transmit channels that transmit the drive signals simultaneously to drive the multi-touch sensor, a receive channel that receives a sense signal resulting from the driving of the multi-touch sensor, a receive oscillator, and a demodulation section that demodulates the received sense signal based on a frequency of the receive oscillator to obtain sensing results, the demodulation section including a demodulator and a vector operator.

An Ultra-Wideband Impulse-Radio Transceiver Chipset Using Synchronized-OOK Modulation

Abstract: This work presents a low-complexity IR-UWB chipset which achieves synchronization and demodulation at the receiver relying only on a ring oscillator clock. The modulation scheme used, synchronized-OOK (S-OOK), permits low power timing acquisition and data reception with a static CMOS digital synchronizer and demodulator counting 61 logic elements. The receiver consists of a modified energy detector (ED) that allows to asynchronously receive UWB pulses in presence of narrowband interference (NBI) with power levels up to -5 and -16 dBm for 5.4 and 2.4 GHz continuous wave interfering signals respectively. The sensitivity is -60/ -66 dBm with an overall energy dissipation of 2.9/3.9 nJ/bit for a 1 Mbps S-OOK PRBS data stream and a 100% power duty cycle. The complete demodulation and synchronization digital back-end consumes only 0.2 mW (including on-chip output buffers) during normal operation. The IR-UWB transmitter is based on a gated LC oscillator and achieves pulse durations of ~2 ns for bandwidths of 500 MHz. It consumes 249 pJ/bit energy per bit at 1 Mbps OOK.

High-Capacity Wireless Signal Generation and Demodulation in 75- to 110-GHz Band Employing All-Optical OFDM

Abstract: We present a radio-frequency (RF) and bit-rate scalable technique for multigigabit wireless signal generation based on all-optical orthogonal frequency-division multiplexing (OFDM) and photonic up-conversion. Coherent detection supported by digital signal processing is used for signal demodulation and data recovery. In order to demonstrate the RF frequency scalability and bit-rate transparency, the system is tested at 60 GHz and in the 75- to 110-GHz band at the baud rates of 5 and 10 Gbaud. In terms of the bit rate, the proposed system is experimentally tested up to 40 Gb/s for wireless signal generation and demodulation. The wireless transmission is not considered in this letter. Additionally, a novel digital carrier phase/frequency recovery structure is employed to enable robust phase and frequency tracking between the beating lasers.

Combining Illumination Dimming Based on Pulse-Width Modulation With Visible-Light Communications Based on Discrete Multitone

Abstract: In the field of indoor wireless networks, visible-light communications is garnering increasing attention. One of the type of emitters used in this technology is white light-emitting diodes, which can synergistically provide both illumination and data transmission. Discrete multitone modulation is attractive for visible-light communications. One of the issues to be addressed in these synergetic use cases is how to incorporate light dimming while not corrupting the communication link. In this paper, the performance of a visible-light communication system combining pulse-width modulation for dimming and discrete multitone for data transmission was investigated. Performance indicators were addressed, i.e., the signal-to-interference ratio due to dimming and the achievable bit-error ratio in the absence of additional noise. By aid of simulations it was shown that practical communication is only feasible when the line rate of the dimming modulation is at least twice the frequency assigned to the largest multitone subcarrier frequency. The results demonstrate that under this constraint and when using a suitably modified demodulation scheme, dimming does not influence the data transmission.

Iq imbalance image compensation in multi-carrier wireless communication systems

Abstract: A method in a wireless communication terminal includes receiving an aggregated carrier including a first component carrier and a second component carrier, determining a level of interference from a signal received on the first component carrier to a signal on the second component carrier based on a signal characteristic of the first component carrier and a signal characteristic of the second component carrier, and providing signal interference information to a serving base station if the determined interference level satisfies a condition.

Chromatic Dispersion Estimation in Digital Coherent Receivers

Abstract: Polarization-diverse coherent demodulation allows to compensate large values of accumulated linear distortion by digital signal processing. In particular, in uncompensated links without optical dispersion compensation, the parameter of the residual chromatic dispersion (CD) is vital to set the according digital filtering function. We present different non-data-aided (blind) CD estimation methods for single-carrier transmission under implementation constraint conditions such as bandwidth limitation and sampling rate. The estimation performance for various modulation formats is compared with respect to precision and robustness for a wide range of combined channel impairments.

Infrared Sensor System for Mobile-Robot Positioning in Intelligent Spaces

Abstract: The aim of this work was to position a Mobile Robot in an Intelligent Space, and this paper presents a sensorial system for measuring differential phase-shifts in a sinusoidally modulated infrared signal transmitted from the robot. Differential distances were obtained from these phase-shifts, and the position of the robot was estimated by hyperbolic trilateration. Due to the extremely severe trade-off between SNR, angle (coverage) and real-time response, a very accurate design and device selection was required to achieve good precision with wide coverage and acceptable robot speed. An I/Q demodulator was used to measure phases with one-stage synchronous demodulation to DC. A complete set of results from real measurements, both for distance and position estimations, is provided to demonstrate the validity of the system proposed, comparing it with other similar indoor positioning systems.

Sensorless Control of IPM Motors in the Low-Speed Range and at Standstill by HF Injection and DFT Processing

Abstract: In this paper, a sensorless controller for an interior permanent-magnet synchronous motor is presented based on well-known high-frequency signal injection techniques. The issue of the demodulation process is the key point of this paper. A novel approach based on discrete Fourier transform and nonconventional reference frame transformation is presented, allowing a simple and robust noncoherent demodulation, i.e., in which no information about the carrier phase is needed. In the classically adopted coherent approaches, in fact, uncertainty about carrier phase reflects in uncertainty in the demodulated signal amplitude, affecting observer gains and signal-to-noise ratio and definitively providing a degradation of the performance of the estimator. Analytical development of the sensorless algorithm, including the demodulation technique, is provided. A complete investigation by simulation is carried out aiming at showing the performance of the proposed method. Finally, experimental results are presented based on a prototype motor drive for city scooters.

Theory And Design Of Digital Communication Systems

Abstract: 1. Introduction 2. Deterministic signal analysis 3. Random signal analysis 4. Information theory and channel coding 5. Communication link analysis 6. Modulation 7. Demodulation 8. Spread spectrum 9. Intersymbol interference and equalization 10. Fading channels.

Varying demodulation to avoid interference

Abstract: In a method of interference avoidance for a capacitive sensor device, a transmitter signal is transmitted with a transmitter electrode of the capacitive sensor device. A resulting signal is received with a receiver electrode of the capacitive sensor device. The resulting signal corresponds to the transmitter signal. A first demodulated output is acquired by demodulating the resulting signal in a first way. A second demodulated output is acquired by demodulating the resulting signal in a second way, where the second way and the first way differ. A shift is made from using the first demodulated output for determining positional information to using the second demodulated output for determining positional information. The shift is based at least in part upon an amount of interference.

Performance of Advanced Receiver Employing Interference Rejection Combining to Suppress Inter-Cell Interference in LTE-Advanced Downlink

Abstract: The interference rejection combining (IRC) receiver is effective in improving the cell-edge user throughput because it suppresses inter-cell interference. The IRC receiver is typically based on the minimum mean square error (MMSE) criteria, which requires channel estimation and covariance matrix estimation including the inter-cell interference with high accuracy. The paper investigates the gain from the IRC receiver taking into account the estimation of the interference signal, i.e., the covariance matrix, in terms of the downlink user throughput performance in a multi-cell environment. For the estimation of the covariance matrix, two estimation schemes are considered one based on data signals and the other based on the demodulation reference signal (DM-RS). In the evaluation, to assess the actual gains of the two schemes, the inter-cell interference signals from the surrounding 56 cells are actually generated in the same way as the desired signals including reference signals, and the channel propagation from all of the cells is explicitly taken into account considering pathloss, shadowing, and multipath fading. The simulation results when the inter-site distance is 500 m and the numbers of transmitter and receiver antennas are 2 and 2, respectively, show that the IRC receiver employing the covariance matrix comprising the interference and noise component estimation improves the cell-edge user throughput (defined as the 5% value in the cumulative distribution function) by approximately 22% compared to the simplified MMSE receiver that approximates the inter-cell interference as AWGN, while the IRC receiver employing the full covariance matrix estimation degrades the average user throughput due to less accurate channel and covariance matrices.

Signal Estimation Under Random Time-Warpings and Nonlinear Signal Alignment

Abstract: While signal estimation under random amplitudes, phase shifts, and additive noise is studied frequently, the problem of estimating a deterministic signal under random time-warpings has been relatively unexplored. We present a novel framework for estimating the unknown signal that utilizes the action of the warping group to form an equivalence relation between signals. First, we derive an estimator for the equivalence class of the unknown signal using the notion of Karcher mean on the quotient space of equivalence classes. This step requires the use of Fisher-Rao Riemannian metric and a square-root representation of signals to enable computations of distances and means under this metric. Then, we define a notion of the center of a class and show that the center of the estimated class is a consistent estimator of the underlying unknown signal. This estimation algorithm has many applications: (1) registration/alignment of functional data, (2) separation of phase/amplitude components of functional data, (3) joint demodulation and carrier estimation, and (4) sparse modeling of functional data. Here we demonstrate only (1) and (2): Given signals are temporally aligned using nonlinear warpings and, thus, separated into their phase and amplitude components. The proposed method for signal alignment is shown to have state of the art performance using Berkeley growth, handwritten signatures, and neuroscience spike train data.

The Design of a Digital Magnetic Induction Tomography (MIT) System for Metallic Object Imaging Based on Half Cycle Demodulation

Abstract: This paper presents several important aspects of a highly integrated, Field Programmable Gate Array (FPGA)-based digital Magnetic Induction Tomography (MIT) system for metallic object imaging applications. Excitation signal generation, receiving signal demodulation, and channel multiplexing control are all implemented inside a Xilinx FPGA (Spartan III). A novel digital demodulation method using only half of the signal cycle is proposed and implemented, which improves the operation speed of the system by two folds. A geometrical scaling relationship has been discovered for MIT sensors, and a particular design has been implemented. Two imaging reconstruction algorithms (Tikhonov Regularization and Total Variation method) are applied to experimental data. The performance of the system has been verified.

A low cost and high efficient acoustic modem for underwater sensor networks

Abstract: Underwater wireless sensor Networks (UWSN) will provide a variety of attractive working fields such as aquaculture, offshore exploitation, biological monitoring as well as water and seafloor pollution, seismic activity and ocean currents. A practical implementation of these applications will require spreading an important number of nodes to facilitate underwater monitoring by means of data acquiring, so it becomes a challenge to develop simple and reliable modem architectures to reduce both the cost in components and the developing time, still being efficient and robust. Moreover power consumption must be also considered due to energy harvesting difficulties in an underwater environment. This work is focused in the design and implementation of a low cost and energy efficient underwater modem. The paper presents a new acoustic modem design based on an original signal-conditioning model optimally adapted to commercial echo sounder based piezoelectric transducers. It represents a very low-cost solution with a power consumption level similar to current terrestrial wireless sensor networks. The modulation and demodulation algorithms are essential to define the modem architecture. In this work, they have been adapted to a low power microcontroller processing capabilities. The proposed modem architecture includes an 8-bit microcontroller and few external analog components. A binary Coherent-FSK modulation has been chosen because it is more efficient in terms of bandwidth than a non-coherent FSK. Coherent FSK modulation algorithm is quite simple, and can be easily implemented in an 8-bit microcontroller with negligible execution time. Demodulation algorithm is more complex and needs a low-power solution. The paper investigates different alternatives, obtaining a new optimal solution including an additional specific processing unit to the microprocessor core. Compared with previous researches that used microcontrollers, the presented approach also improves energy efficiency without lowering bit rate and bandwidth efficiency. The design has a variable gain reception to measure precisely the incoming signal level and obtaining signal quality indicators similar to RSSI used in wireless RF sensor networks. The circuit has been simulated and experimentally tested too with a prototype. Several tests have been carried out using the different alternatives presented. The goal of the first experiments was to characterize the frequency response of the transducers, and validate acoustic wave generation and amplification models obtained by means of simulation. Measurements were also taken to obtain receiver sensitivity and communication efficiency to power variations. Efficient design of both power amplifier and receiver analog processing stages, combined with optimal microcontroller power saving modes has extended estimated battery. As a conclusion, a worthwhile modem has been designed with the following advantages: Ultra-Low power consumption, a small form factor and a low final cost which enable future low cost deployment of underwater sensor networks.

Analytical estimation of phase noise influence in coherent transmission system with digital dispersion equalization

Abstract: We present a novel investigation on the enhancement of phase noise in coherent optical transmission system due to electronic chromatic dispersion compensation. Two types of equalizers, including a time domain fiber dispersion finite impulse response (FD-FIR) filter and a frequency domain blind look-up (BLU) filter are applied to mitigate the chromatic dispersion in a 112-Gbit/s polarization division multiplexed quadrature phase shift keying (PDM-QPSK) transmission system. The bit-error-rate (BER) floor in phase estimation using an optimized one-tap normalized least-mean-square (NLMS) filter, and considering the equalization enhanced phase noise (EEPN) is evaluated analytically including the correlation effects. The numerical simulations are implemented and compared with the performance of differential QPSK demodulation system.

Phase difference of arrival distance estimation for RFID tags in frequency domain

Abstract: The paper gives an overview of phase based ranging techniques, focusing on the phase difference of arrival method measured in frequency domain (FD-PDoA). After a theoretical overview of distance estimation and localization, it introduces an experimental RFID front-end prototype used for FD-PDoA measurements. Proposed modular design is very flexible and allows easy replacement of any block, as well as direct access to all required low-level signals. The main part of the article is devoted to range estimation experiments in an anechoic chamber, using the developed front-end and signal processing in a PC with MATLAB. Several measurement problems are addressed, such as demodulator phase imbalance correction, wrapped phase recovery, etc. Ranging is performed with common passive EPC Gen2 RFID tags.

Six-Port Gigabit Demodulator

Abstract: This paper presents measurement results for a six-port-based demodulator designed for a center frequency of 7.5 GHz and with a bandwidth of 1 GHz for operation in the ultra-wideband band. The demodulator includes the six-port correlator, diodes, and amplifiers needed to recover the baseband data. Measurement results show that the prototype supports data rates at 1.7 Gbit/s with bit-error rate if a two-tap linear equalizer is used and bit-error rate if only threshold detection is used. The measured performance of the used six-port correlator including the amplifiers is presented and their influence on the overall system performance is discussed. Limitations in the present system and possible improvements are also considered.

Weighted Energy Detection for Noncoherent Ultra-Wideband Receiver Design

Abstract: For ultra-wideband (UWB) impulse radios, noncoherent energy detectors are motivated for their simple circuitry and effective capture of multipath energy. A major performance-degrading factor in energy detection is the noise floor, which is aggravated for low-duty-cycle UWB signals with a large time-bandwidth product. In this paper, weighted energy detection (WED) techniques are developed for effective noise suppression. The received signal is processed by a set of parallel integrators, each corresponding to a different integration time-window within a symbol period. The outputs of these integrators are weighted and linearly combined to generate decision statistics, while the weights are determined by the signal power collected from the corresponding integrators to improve the effective signal to noise ratio. The WED principle is applied to all phases of receiver processing, including signal detection, timing synchronization and data demodulation. For each phase, the optimal linear detector parameters, including decision thresholds and weighting coefficients, are derived analytically. Simulations show that the proposed noncoherent WED receiver enhances the bit-error-rate performance compared to conventional energy detectors.

Design of 1.2-V Broadband High Data-Rate MMW CMOS I/Q Modulator and Demodulator Using Modified Gilbert-Cell Mixer

Abstract: In this paper, low-voltage evolution and high-speed operation mixer design are presented for millimeter-wave (MMW) CMOS in-phase/quadrature (I/Q) modulator and demodulator. The modified Gilbert-cell mixer architecture, which eliminates the three-level transistors stacking in the conventional Gilbert-cell mixer, can operate at a reduced supply voltage while maintaining reasonable performance. In addition, IF transimpedance amplifier buffer and wideband RF design are introduced to increase the operation speed of the mixer for MMW gigabit wireless transmission link applications. Using a 0.13-μm CMOS process, the I/Q modulator and demodulator formed with the modified Gilbert-cell mixers are demonstrated at the MMW. Under 1.2-V standard supply voltage, the modulator and demodulator exhibit excellent conversion gain (CG) flatness of -3.5 ±1.5 dB and -3 ±1.5 dB from 41 to 69.5 GHz and 31 to 69 GHz, respectively. For 60-GHz wireless personal area network applications, π/4 differential quadrature phase-shift keying, 16 quadrature amplitude modulation, and binary phase-shift keying modulation signal tests are successfully performed through the direct-conversion system. The results show that the presented monolithic microwave integrated circuits can operate at low-voltage and low-power while providing good CG and high data rate, even up to multigigabit.