Showing papers on "Digital signal published in 2007"

Vlsi Digital Signal Processing Systems: Design And Implementation

Abstract: Introduction to Digital Signal Processing Systems. Iteration Bound. Pipelining and Parallel Processing. Retiming. Unfolding. Folding. Systolic Architecture Design. Fast Convolution. Algorithmic Strength Reduction in Filters and Transforms. Pipelined and Parallel Recursive and Adaptive Filters. Scaling and Roundoff Noise. Digital Lattice Filter Structures. Bit-Level Arithmetic Architectures. Redundant Arithmetic. Numerical Strength Reduction. Synchronous, Wave, and Asynchronous Pipelines. Low-Power Design. Programmable Digital Signal Processors. Appendices. Index.

Source digital camcorder identification using sensor photo response non-uniformity

Abstract: Photo-response non-uniformity (PRNU) of digital sensors was recently proposed [1] as a unique identification fingerprint for digital cameras. The PRNU extracted from a specific image can be used to link it to the digital camera that took the image. Because digital camcorders use the same imaging sensors, in this paper, we extend this technique for identification of digital camcorders from video clips. We also investigate the problem of determining whether two video clips came from the same camcorder and the problem of whether two differently transcoded versions of one movie came from the same camcorder. The identification technique is a joint estimation and detection procedure consisting of two steps: (1) estimation of PRNUs from video clips using the Maximum Likelihood Estimator and (2) detecting the presence of PRNU using normalized cross-correlation. We anticipate this technology to be an essential tool for fighting piracy of motion pictures. Experimental results demonstrate the reliability and generality of our approach.

Digital alias-free signal processing

Abstract: As demand for applications working in extended frequency ranges increases, classical Digital signal processing (DSP) techniques, not protected against aliasing, are becoming less effective. Digital alias-free signal processing (DASP) is a technique for overcoming the problems of aliasing at extended frequency ranges. Based on non-uniform or randomised sampling techniques and the development of novel algorithms, it creates the capacity to suppress potential aliasing crucial for high frequency applications and to reduce the complexity of designs. This book provides practical and comprehensive coverage of the theory and techniques behind alias-free digital signal processing.

Antenna array system

Abstract: Antenna system connectable to a base station, the antenna system comprising a digital radio unit (200) connectable to at least one antenna element (220), wherein the digital radio unit (200) comprises: at least one micro radio (230) for receiving/sending digital radio signals having a digital down-converter (350) / a digital up-converter (310) and a digital signal converter (234; 235). The at least one micro radio (230) converts the digital radio signals to analogue RF (radio frequency) signals and vice versa. The at least one micro radio (23) has at least one hub (240) for processing digital radio signals and control signals and for routing said digital radio signals and control signals via at least one serial link (260) and at least one interface (258, 259). The at least one serial link (260) is provided between the at least one hub (240) and the at least one micro radio (230).

Analog signal path modeling for self-interference cancellation

Abstract: Described herein is a device that includes at least one radio frequency transmitter; at least one radio frequency receiver; a copy block configurable to output a digital representation of a currently transmitted signal and a model having a representation of at least analog circuitry of the at least one radio frequency transmitter and analog circuitry of the at least one radio frequency receiver, as well as possibly one or more antennas. The model generates, in response to the digital representation of the currently transmitted signal, a self-interference compensation signal to compensate, in the digital domain, a signal that is received simultaneously with the currently transmitted signal. Also described are corresponding apparatus, methods, computer program instructions stored in a memory medium, and an integrated circuit embodiment.

Analog-to-digital converter and semiconductor device

Abstract: An analog to digital converter comprising a reference signal generator, a comparator, and a counter wherein the reference signal generator is operable to generate a reference for converting an analog signal into a digital signal. The reference signal generator is also operable to generate a plurality of the reference signals based on the change in a voltage. The comparator is operable to compare the analog signal with the reference signal generated by the reference signal generator. The counter is operable to count, in parallel with a comparison performed by the comparator, a predetermined count clock and to hold a count value at the time of completion of the comparison.

Analog-digital converter circuit

Abstract: The present invention provides a multi-input A/D converter circuit capable of shorting a conversion time without increasing its layout area and current consumption. When a most significant bit of a binary counter is “L”, individual input signals are sampled by a sample and hold unit, and digital signals held in respective data holders are sequentially selected by a selector. When the most significant bit is brought to “H”, the respective input signals are held as analog signals and compared with each of reference voltages produced corresponding to a digital signal by a DAC. When decision signals outputted from comparators are changed from “L” to “H”, the digital signal at that time is held in the individual data holders as digital signals.

Digital Camera with Selectively Increased Dynamic Range By Control of Parameters During Image Acquisition

Abstract: A parameter of a digital camera or other digital image acquisition device is adjusted to maintain the resulting digital signal within a range carried by a digital processing path that carries a limited number of bits. The magnitude of the parameter is then also used to represent the image. Examples of the parameter include analog signal gain and exposure time. This is a cost effective way to increase the dynamic range of a digital camera, instead of increasing the width of its digital processing path. The digital data may be processed to obtain either tone mapped images, which are compatible with current cameras and other equipment, or to obtain images with a greater dynamic range for use with suitable displays and the like.

Robust scanner identification based on noise features

Abstract: A large portion of digital image data available today is acquired using digital cameras or scanners While cameras allow digital reproduction of natural scenes, scanners are often used to capture hardcopy art in more controlled scenarios This paper proposes a new technique for non-intrusive scanner model identification, which can be further extended to perform tampering detection on scanned images Using only scanned image samples that contain arbitrary content, we construct a robust scanner identifier to determine the brand/model of the scanner used to capture each scanned image The proposed scanner identifier is based on statistical features of scanning noise We first analyze scanning noise from several angles, including through image de-noising, wavelet analysis, and neighborhood prediction, and then obtain statistical features from each characterization Experimental results demonstrate that the proposed method can effectively identify the correct scanner brands/models with high accuracy

Characterization of GSM Non-Line-of-Sight Propagation Channels Generated in a Reverberating Chamber by Using Bit Error Rates

Abstract: In this paper, it is shown how a large mode-stirred reverberating chamber can be used to physically generate a set of non-line-of-sight propagation channels, which are naturally and objectively classified by means of the bit error rate (BER) norm. The experiments are accomplished at the mode-stirred reverberating chamber of the Universita di Napoli Parthenope (formerly Istituto Universitario Navale), and the electromagnetic input signal is a global system for mobile communications, one at 1.8 GHz. It is shown that it is possible to change the BER by means of the stirring process and/or the chamber loading. The proposed technique calls for fast measurements, and therefore, it is amenable to industrial use. The methodology is general and suitable to any digital electromagnetic signal, provided no distortion of modulation occurs.

Filter circuit for noise cancellation, noise reduction signal production method and noise canceling system

Abstract: There is provided a filter circuit for producing a noise reduction signal for reducing a noise signal collected by a microphone, including: a digital section including an analog/digital conversion section configured to convert the noise signal into a digital noise signal, a digital filter section configured to produce a digital noise reduction signal based on the digital noise signal, and a digital/analog conversion section configured to convert the digital noise reduction signal into an analog noise reduction signal; an analog path connected in parallel to said digital section and configured to output the noise signal as it is or after processed by an analog filter; and a synthesis section configured to synthesize the analog noise reduction signal outputted from said digital/analog conversion section of said digital section and the analog signal outputted from said analog path to produce a noise reduction signal to be used for noise reduction.

Encrypting the output of a card reader in a card authentication system

Abstract: Systems and methods for encrypting the output of a card reader in a card authentication system are provided. In one embodiment, the invention relates to a method for reading a data card having an intrinsic magnetic characteristic and recorded data on the data card using a read head including a magnetic sensor having a housing, an analog to digital converter located within the housing and a processor located within the housing, the method including generating an analog signal indicative of the intrinsic magnetic characteristic and the recorded data of the data card, converting the analog signal into a digital signal, generating a magnetic fingerprint based on the intrinsic magnetic characteristic from the digital signal, extracting the recorded data from the digital signal, encrypting at least a portion of the recorded data, storing the magnetic fingerprint and the recorded data, and outputting the encrypted at least the portion of the recorded data.

Digital Control Generations -- Digital Controls for Power Electronics through the Third Generation

Abstract: Digital control in power electronics can be divided into three "generations" First-generation digital controls use digital "outside the loop" in communications, setup, and supervisory roles Second generation digital controls use digital processes "inside the loop," including discrete-time feedback loops and sometimes even digital signal processing Today, first-generation digital methods are expanding quickly, as new communication protocols and adjustable analog loops become common Even companies that continue to design analog controls for power electronics often include these types of digital processes Second-generation digital controls are a hot topic right now, as real-time digital controllers become feasible In third-generation digital controls, the digital process functions directly with individual switches to push performance up to the physical limits of power electronics A digital switch decides when it must turn on or off The control is on direct switch timing rather than a converter duty ratio or a setting Extreme performance is possible with this approach, such as converters that do not exhibit output disturbances when confronted with load or line step changes The talk compares these different arenas, all of which are current active topics in power electronics, and shows what can become possible as the third generation develops

Narrow Pulse Elimination PWM for Multilevel Digital Audio Power Amplifiers Using Two Cascaded H-Bridges as a Nine-Level Converter

Abstract: This paper presents a methodology to reduce total harmonic distortion (THD) in digital audio power amplifiers, using two new approaches: 1) a multilevel converter made of two cascaded full-bridges, with suitable power supplies to operate as a nine-level hybrid type converter and 2) a new pulsewidth modulation (PWM) technique called narrow pulse elimination (NPE) PWM. The proposed nine-level converter uses only eight MOSFETs. Unlike conventional PWM, the NPE PWM does not generate excessively narrow pulses, so that power semiconductors nonideal delays and switching times are still negligible. Therefore, the nine-level output voltage THD, mostly introduced in the power stage, is strongly reduced. With the NPE technique, the resolution of the generated PWM is no longer limited by the switching speed of the output switches, but only by the frequency of digital processing circuit. Simulation and experimental results from a laboratory prototype are presented in order to show the effectiveness of the proposed approaches

Active damping of LCL resonance with minimum sensor effort by means of a digital infinite impulse response filter

Abstract: This paper presents a concept for active damping of an LCL filter connecting a digitally controlled PWM converter to the grid Active damping is performed by means of a digital Infinite Impulse Response (IIR) filter Digital filters, being well known in digital signal analysis, can easily be implemented when using digital controllers and require very low computational effort In contrast to active damping solutions found in literature, no extra quantities except the controlled current must be sensed This functionality is proven via experimental results After a short introduction of the problem and an overview of solutions found in literature, the implemented fundamental procedure for active damping is described Subsequently, the main idea of using an IIR filter for active damping, being an approximation to a derivative function, is qualified and the design procedure is presented In this paper it is stated that with this method the sensors are minimized and that due to the approximation of the derivative function the damping performance is lower compared to solutions found in literature However, the damping effect by using an IIR filter is proven The use of IIR filters and the reduction of sensor effort for active damping of EMI filters with multiple passives looks promising also for other applications with a known load

Wireless digital transmission system for loudspeakers

Abstract: This invention relates to a wireless digital transmission system for loudspeakers comprising: compression means for the file representing the digital audio signal of the “compact disc” type, a transmission device comprising means of converting this compressed signal into a series signal moving by packets going to a modulator circuit with phase quadrature and means of transmitting the signals exiting the modulator circuit with phase quadrature to the domestic network for feeding electricity; a receiving device comprising means of connecting to this domestic network and of extracting from the feed electrical signal, by a demodulator with phase quadrature, data packets moving the digital audio signal to convert it into a parallelized digital signal sent to a decompression circuit; means of converting the decompressed digital signals into an analog signal intended to feed a loudspeaker after adequate amplification.

Nonlinear digital signal processor

Abstract: A digital signal processor (DSP) comprises an input terminal configured to receive an input, an adaptive nonlinear phase filter coupled to the input terminal, the adaptive nonlinear phase filter having a time-varying phase response, and an adaptive nonlinear amplitude filter coupled to the input terminal, the adaptive nonlinear amplitude filter having a time-varying amplitude response. A method of processing a signal comprises receiving the signal, sending the signal to an adaptive nonlinear phase filter, the adaptive nonlinear phase filter having a time-varying phase response, and sending the signal to an adaptive nonlinear amplitude filter, the adaptive nonlinear amplitude filter having a time-varying amplitude response.

Detection, communication and control in multimode cellular, TDMA, GSM, spread spectrum, CDMA, OFDM WiLAN and WiFi systems

Abstract: Detection device for detection and generation of detection device generated signal, processed with remote control device generated remote control signal, with location finder or location tracker or navigation signal and with Modulation Demodulation (Modem) Format Selectable (MFS) communication signal. Processor for processing a digital signal into cross-correlated in-phase and quadrature-phase filtered signal and for processing a voice signal into Orthogonal Frequency Division Multiplexed (OFDM) or Orthogonal Frequency Division Multiple Access (OFDMA) signal. Detection device generated signal and location finder signal, with OFDM or OFDMA processed voice signal is used in a Wireless Local Area Network (WLAN) and in Voice over Internet Protocol (VoIP) network. Detection device generated signal and location finder signal with Time Division Multiple Access (TDMA), Global Mobile System (GSM) and spread spectrum Code Division Multiple Access (CDMA) signal is used in a cellular network. Polar and quadrature modulator and two antenna transmitter for transmission of provided processed signal. Transmitter with two amplifiers operated in separate radio frequency (RF) bands. One transmitter is operated as a Non-Linearly Amplified (NLA) transmitter and the other transmitter is operated as a linearly amplified or linearized amplifier transmitter. Two antenna receiver and demodulator. Diversity receiver and demodulator.

New approaches to encryption and steganography for digital videos

Abstract: In this work we propose a novel type of digital video encryption that has several advantages over other currently available digital video encryption schemes. We also present an extended classification of digital video encryption algorithms in order to clarify these advantages. We analyze both security and performance aspects of the proposed method, and show that the method is efficient and secure from a cryptographic point of view. Even though the method is currently feasible only for a certain class of video sequences and video codecs, the method is promising and future investigations might reveal its broader applicability. Finally, we extend our approach into a novel type of digital video steganography where it is possible to disguise a given video with another video.

Radio communication apparatus, radio communication system, digital radio-over-fiber communication method and program

Abstract: PROBLEM TO BE SOLVED: To provide a common radio communication apparatus which stores many terminal systems having various kinds of radio communication systems. SOLUTION: The apparatus has a first storage portion which stores a digital signal digital-converted in such a state that a radio signal sent out of a first communication apparatus is not demodulated, a demodulation system selecting portion which selects and demodulates a modulation-demodulation system for demodulating the digital signal to be stored in the first storage portion, a second storage portion which stores the digital signal demodulated by the demodulation system selecting portion, and data transmitter which reads the digital signal stored in the second storage portion, extracts data requested from the read digital signal and transmits it to a second communication apparatus when a transmission request of the data to be transmitted from the second communication apparatus is brought. COPYRIGHT: (C)2008,JPO&INPIT

Thresholded samplers for UWB impulse radar

Abstract: This paper presents two novel methods for sampling the backscatter in an impulse radar system. The authors have called the two related methods for swept threshold and stochastic resonance sampling. The samplers are simple, mostly digital circuits which are not clocked, but instead utilize continuous-time signal processing. Since fine-pitch CMOS is not very good for analog processing, but instead has very fast digital logic, the samplers are well suited for this technology. An implementation in 90 nm CMOS is described and measurements which confirm a working 23 GHz sampler are shown

Digital current mode controller

Abstract: A digital current-mode controller for a DC-DC converter is disclosed. The controller comprises a digital current reference; and a current loop compensator adapted to receive a digital current error signal derived from a digital current sample sensed from the DC-DC converter and the digital current reference and to generate a duty-cycle command, wherein the current loop compensator comprises a low-pass filter that is used in generating the duty-cycle command. A DC-DC regulator comprising a digital current-mode controller and a method of controlling a DC-DC converter are also disclosed.

Reducing collisions in beamforming wireless systems

Abstract: A device comprising transceiver logic and control logic coupled to the transceiver logic. The control logic is adapted to use the transceiver logic to broadcast a signal comprising either a Request-to-Send (RTS) signal or a Clear-to-Send-to-Self (CTS2S) signal to a plurality of other devices. The signal is adapted to cause the plurality of other devices to refrain from transmitting data. After at least some of the plurality of other devices have received the signal, the transceiver logic transmits at least part of another signal using beamforming techniques.

Chaotic signal transmitter using pulse shaping method

Abstract: The invention relates to a chaotic signal transmitter using a pulse shaping method to amplitude-modulate a chaotic signal according to a transmission signal, thereby transmitting the chaotic signal having various slopes. The chaotic signal transmitter includes a waveform converter for blocking high frequency component of the transmission signal to convert the waveform of the transmission signal and a chaotic signal generator for generating the chaotic signal. The chaotic signal transmitter further includes a modulator for amplitude-modulating the chaotic signal according to the waveform-converted transmission signal.

Method and apparatus for improving quality of service for reception in digital television broadcast systems

Abstract: A method of transmitting a digital data stream to a receiver unit. The method includes the steps of modulating a digital data stream in accordance with a modulation technique so as to generate a modulated digital data stream; providing the modulated digital data stream to a transmitter unit operable for transmitting the modulated digital data stream; receiving the transmitted digital data stream by the receiver unit, where the receiver unit generates signal reception data indicating the quality of reception of the modulated digital data stream; and providing the signal reception data indicating the quality of reception of the modulated digital data stream to a quality control processing unit via a communication channel, where the quality control processing unit analyzes the signal reception data to determine if the quality of reception of the modulation digital data stream by the receiver unit is below a predefined level, and if so, adjusts the modulation technique being applied so as to improve the quality of reception by the receiver unit.

Operating Method for a Sensor and a Control Facility Communicating With the Sensor

Abstract: A sensor has a detection device and an evaluation device to detect an analog signal, to determine a digital signal and to transmit the digital signal to a control device outside the sensor. The analog signal and/or the digital signal is supplied to a monitoring device of the sensor. An enable signal is transmitted to the control device only if the device being monitored is operating correctly. In a normal mode, the control device processes the digital signal further. Otherwise, it deems the transmitted digital signal to be defective and outputs a message using a malfunction of the sensor. On account of the transmission of the test signal, the sensor assumes a test mode in which it manipulates the signals which are supplied to the monitoring device in such that the monitoring device detects that the device being monitored is not operating correctly. In the test mode, the control device outputs a message using a malfunction of the sensor if the enable signal is transmitted to it in addition to each.

Analog to digital conversion using recurrent neural networks

Abstract: A system for converting an analog signal into a digital data stream includes a recurrent network with a plurality of converter circuits that individually receive the same analog signal as input. The circuits then generate a plurality of spike outputs that exhibit characteristics of the analog signal. Interconnecting feedback loops from each circuit output to the input of neighboring circuits queues the plurality of spike outputs to thereby self- organize the network. A digital clock is then used to establish predetermined time intervals for counting the spike outputs to create the digital data stream.

Power management in digital receivers

Abstract: Methods and systems consistent with the present invention provide a method for dynamically controlling power consumption in a digital demodulator circuit by varying clock rates and bit widths of demodulator components including an analog to digital converter, decimation filter, OFDM operating engine, FEC decoder, and MPE-FEC processor, according to parameters and conditions of the received signal including modulation mode, signal to noise ratio, effective bit transmission rate, bit error rate, packet error rate, adjacent channel interference, and co-channel interference.

Digitally-Enhanced Phase-Locking Circuits

Abstract: In this paper, we present an overview of digital techniques that can overcome the drawbacks of analog phase-looked loops (PLLs) implemented in deep-submicron CMOS processes. The design of key building blocks of digital PLLs such as the time-to-digital converter and digital-to-frequency converters are discussed in detail. The implementation and measured results of two digital PLL architectures, (1) based on a digitally controlled oscillator and (2) based on a digital phase accumulator, are presented. The experimental results demonstrate the feasibility of using digital PLLs in digital systems requiring high-performance PLLs.

Non-Data-Aided Approach to I/Q Mismatch Compensation in Low-IF Receivers

Abstract: A digital signal processing (DSP) technique is presented that can compensate for the in-phase/quadrature-phase (I/Q) mismatch in low-intermediate frequency (IF) receivers. In particular, a non-data-aided (NDA) I/Q mismatch estimator is derived by exploiting the statistical independence between desired and image signals. The proposed technique obtains two baseband signals (uncompensated desired and image signals) from a digital IF signal and processes them to estimate and compensate for the I/Q mismatch. The mean-square error (MSE) of the estimate is analyzed. Computer simulation results indicate that the proposed technique can outperform existing adaptive DSP techniques that are based on the use of blind signal separation algorithms. It is observed that the image rejection ratio (IRR) of the proposed technique decreases monotonically with the number of observed samples for estimation, while that of conventional methods exhibits some floor.