Showing papers on "Offset (computer science) published in 2005"

Measuring orientation of human body segments using miniature gyroscopes and accelerometers

Abstract: In the medical field, there is a need for small ambulatory sensor systems for measuring the kinematics of body segments. Current methods for ambulatory measurement of body orientation have limited accuracy when the body moves. The aim of the paper was to develop and validate a method for accurate measurement of the orientation of human body segments using an inertial measurement unit (IMU). An IMU containing three single-axis accelerometers and three single-axis micromachined gyroscopes was assembled in a rectangular box, sized 20×20×30 mm. The presented orientation estimation algorithm continuously corrected orientation estimates obtained by mathematical integration of the 3D angular velocity measured using the gyroscopes. The correction was performed using an inclination estimate continuously obtained using the signal of the 3D accelerometer. This reduces the integration drift that originates from errors in the angular velocity signal. In addition, the gyroscope offset was continuously recalibrated. The method was realised using a Kalman filter that took into account the spectra of the signals involved as well as a fluctuating gyroscope offset. The method was tested for movements of the pelvis, trunk and forearm. Although the problem of integration drift around the global vertical continuously increased in the order of 0.5°s −1, the inclination estimate was accurate within 3° RMS. It was shown that the gyroscope offset could be estimated continuously during a trial. Using an initial offset error of 1 rads −1, after 2 min the offset error was roughly 5% of the original offset error. Using the Kalman filter described, an accurate and robust system for ambulatory motion recording can be realised.

What Undermines Aid’s Impact on Growth?

Abstract: Why it is so hard to find a robust effect of aid on the long-term growth of poor countries, even those with good policies. A possible offset to the beneficial effects of aid is examined using a methodology that exploits both cross-country and within-country variation.

High-SNR power offset in multiantenna communication

Abstract: The analysis of the multiple-antenna capacity in the high-SNR regime has hitherto focused on the high-SNR slope (or maximum multiplexing gain), which quantifies the multiplicative increase as a function of the number of antennas. This traditional characterization is unable to assess the impact of prominent channel features since, for a majority of channels, the slope equals the minimum of the number of transmit and receive antennas. Furthermore, a characterization based solely on the slope captures only the scaling but it has no notion of the power required for a certain capacity. This paper advocates a more refined characterization whereby, as a function of SNR|/sub dB/, the high-SNR capacity is expanded as an affine function where the impact of channel features such as antenna correlation, unfaded components, etc., resides in the zero-order term or power offset. The power offset, for which we find insightful closed-form expressions, is shown to play a chief role for SNR levels of practical interest.

Fast FFT based GPS satellite acquisition methods

Abstract: A Global Positioning System (GPS) receiver uses satellite signals to determine position, velocity, and timing information. Measurements are obtained by synchronising the locally generated signal in the receiver with the signals received. A synchronisation procedure called acquisition adjusts the code phases of the incoming signal and the locally generated pseudo-random replica sequence of the corresponding satellite to a small timing offset and finds the residual frequency modulation after carrier wipe-off. New fast techniques for acquiring signals indoors in conditions that require a significant number of computations are presented. In this work many arithmetic operations are shared when exploring different search options by using fast Fourier transform (FFT) and a technique based on the frequency domain replica shifting. It is shown that FFT can be used for the joint processing of multiple (code-phase/frequency) search options in both dimensions at once. With a slight degradation in performance, the algorithm has a modified version that implements the technique using two-dimensional FFT. Several possible processing schemes are presented. Moreover, the presented shifting replica approach in the frequency domain can significantly reduce computational complexity by jointly acquiring different satellites.

Synchronization method based on a new constant envelop preamble for OFDM systems

Abstract: The synchronization method using the available constant envelop preamble is analyzed, and a new preamble weighted by pseudo-noise sequence is proposed, with which a novel timing and frequency offset estimation method is presented for orthogonal frequency division multiplexing (OFDM) systems in this paper. By the proposed method, the accuracy of the timing offset estimator is significantly improved, and the estimate range of the frequency offset estimator is greatly enlarged with no loss in accuracy. The performance of the proposed method is demonstrated by simulations.

Dynamic vergence and focus control for head-mounted displays

Abstract: Systems and methods for dynamically controlling vergence and focus for a see-through head-mounted display (ST-HMD) used as part of an augmented reality (AR) system are disclosed. The ST-HMD ( 40 ) allows a user ( 30 ) to view left and right images ( 150 L, 150 R) through corresponding left and right eyepieces ( 104 L, 104 R) so that a single virtual object ( 150 V) based on the right and left images as seen at a real object such as a screen ( 20 ). When the user moves relative to the real object, however, the vergence changes and the virtual object does not appear in focus at the real object. Changes in the vergence are compensated by tracking the user's head position with a tracking unit ( 350 ) and providing the tracking data to a controller ( 180 ). Based on the tracking data and the interpupilary distance (IPD) of the user, the controller calculates the offset (H) needed to be imparted to the images formed in the eyepieces to maintain the vergence of the virtual object at the real object even when the user's position changes relative to the real object.

Imaging device with multiple fields of view incorporating memory-based temperature compensation of an uncooled focal plane array

Abstract: A plurality of temperature dependent focal plane arrays operate without a temperature stabilization cooler and/or heater over a wide range of ambient temperatures. Gain, offset and/or bias correction tables are provided in a flash memory in memory pages indexed by the measured temperature of the focal plane arrays. The memory stores a calibration database, which is accessed using a logic circuit which generates a memory page address from a digitized temperature measurement of each of the focal plane array. The calibration database is comprised of an array of bias, gain and offset values for each pixel in the focal plane array for each potential operating temperature over the entire range of potential operating temperatures. The bias, gain and offset data within the database are read out, converted to analog form, and used by analog circuits to correct the focal plane array response. The output of each of the FPAs is multiplexed to a shared processing module and calibration data for each of the FPAs is accessed from the shared processing module.

System and method for clock synchronization over packet-switched networks

Abstract: Embodiments of the invention enable the synchronization of clocks across packet switched networks, such as the Internet, sufficient to drive a jitter buffer and other quality-of-service related buffering. Packet time stamps referenced to a local clock create a phase offset signal. A shortest-delay offset generator uses a moving-window filter to select the samples of the phase offset signal having the shortest network propagation delay within the window. This shortest network propagation delay filter minimizes the effect of network jitter under the assumption that queuing delays account for most of the network jitter. The addition of this filtered phase offset signal to a free-running local clock creates a time reference that is synchronized to the remote clock at the source thus allowing for the transport of audio, video, and other time-sensitive real-time signals with minimal latency.

Method for correction of relative object-detector motion between successive views

Abstract: Motion correction for optical tomographic imaging in three dimensions. An object of interest (1) is illuminated to produce an image (111). A lateral offset correction value is determined for the image (114). An axial offset correction value is determined for the image 115). The lateral offset correction value and the axial offset correction value are applied to the image to produce a corrected file image (116).

Continuously varying offset mark and methods of determining overlay

Abstract: The present invention relates to overlay marks and methods for determining overlay error. One aspect of the present invention relates to a continuously varying offset mark. The continuously varying offset mark is a single mark that includes over laid periodic structures, which have offsets that vary as a function of position. By way of example, the periodic structures may correspond to gratings with different values of a grating characteristic such as pitch. Another aspect of the present invention relates to methods for determining overlay error from the continuously varying offset mark. The method generally includes determining the center of symmetry of the continuously varying offset mark and comparing it to the geometric center of the mark. If there is zero overlay, the center of symmetry tends to coincide with the geometric center of the mark. If overlay is non zero (e.g., misalignment between two layers), the center of symmetry is displaced from the geometric center of the mark. The displacement in conjunction with the preset gain of the continuously varying offset mark is used to calculate the overlay error.

Joint weighted least-squares estimation of carrier-frequency offset and timing offset for OFDM systems over multipath fading channels

Abstract: This work presents an algorithm for joint estimation of carrier-frequency offset and timing offset for orthogonal frequency-division multiplexing (OFDM) systems in the tracking mode. The proposed weighted least-squares algorithm derives its estimates based on phase differences in the received pilot subcarrier signals between two symbols. Moreover, the optimal weights in two different channel conditions are derived. Both analysis and simulation show that the weighted least-squares algorithm can effectively and accurately estimate the carrier-frequency offset as well as the timing offset of OFDM signals in multipath fading channels.

A lane departure warning system using lateral offset with uncalibrated camera

Abstract: In this paper, we propose an automatic method for determining the lateral offset of the vehicle with respect to the center of the lane. Initially, a linear-parabolic model is used to detect lane boundaries. The linear part of the model is then used to obtain an estimation of the lateral offset, without the knowledge of any intrinsic or extrinsic camera parameter. Finally, the analysis the offset across time is then used to determine a lane departure measure, allowing lane crossings to be detected in advance.

Methods for establishing wireless network communication and device utilizing same

Abstract: Method for establishing wireless networks between devices is disclosed. When a first device is activated to establish a wireless network with other devices, a first activation reference time is recorded. At least one second device that has at least one compatible networking capability is searched for and identified. When the second device is activated to establish wireless network with other devices, a second activation reference time also is recorded. The first and second activation reference times are compared to determine whether they fall into the same time window. The offset between the system time of the first device and that of the second may be factored into the calculation to further enhance the accuracy. If the first and second activation reference times are in the same time window, the authentication of wireless network is established between the devices.

Computed tomography with increased field of view

Abstract: A volumetric computed tomography system with a large field of view has, in a forward geometry implementation, multiple x-ray point sources emitting corresponding fan beams at a single detector array. The central ray of at least one of the fan beams is radially offset from the axis of rotation of the system by an offset distance D. Consequently, the diameter of the in-plane field of view provided by the fan beams may be larger than in a conventional CT scanner. Any number of point sources may be used. Analogous systems may be implemented with an inverse geometry so that a single source array emits multiple fan beams that converge upon corresponding detectors.

Staggered memory cell array

Abstract: A method of placing a cell in an array is disclosed. The method includes placing the cell a plurality of times (600, 602, 604) in a first array. The cell is also placed a plurality of times (606, 608, 610) in a second array. The second array is placed adjacent and offset from the first array by an offset distance (O2).

System and Method for Asymmetric Offsets in a Risk Management System

Abstract: A system and method for using asymmetrical offsets for products in a risk management analysis system are disclosed. Conventional systems assign symmetrical offsets for products, that is, if two products have an 80% correlation they each would be assigned an offset of 80% with respect to each other. However, it is desirable to allow for asymmetrical offsets. In the disclosed system and method, when two products have a correlation of 80%, one may be assigned an offset of 75% and the other may be assigned an offset of 80%. There are many reasons to vary the offset between the products. The varying offset may reflect an asymmetry in the risk in one of the products, such as being traded in an illiquid market or in a less desirable venue. The varying offset may correct for an imbalance in spread credits due to special charges from intra spreading.

System and Method for Efficiently Using Collateral for Risk Offset

Abstract: A system and method for analyzing correlation between the assets given by the trader for collateral and that trader's open positions is disclosed. Thus, if the collateral is correlated to the trader's open positions, then some offset can be given. If there is no correlation than the collateral is valued in the conventional way. For example, if a trader provides t-bills as collateral for an account that has open positions (e.g. short futures) in T-bills, than that trader's account can be credited with some offset since the value of T-bills and T-bill futures are highly correlated.

User controlled graphics object movement based on amount of joystick angular rotation and point of view angle

Abstract: Three-dimensional image display game system and method for use with a display for displaying an object in a three-dimensional space, including an operation controlling device including an operating member having a base end rotatably supported and a free end operable by an operator. The operation controlling device includes an inclination amount data output detector which detects an inclination amount of the operating member to output inclination amount data. The system further includes direction determining circuitry operable to determine a direction that corresponds to an inclination direction of the operating member based on the inclination amount data, and moving object direction determining circuitry which determines a moving direction of the object in three-dimensional space based upon the direction determined by the direction determining circuitry and a point of view angle at which the object is being viewed by the operator in three-dimensional space. A direction in which the operating member must be moved to cause forward movement of the object is offset from a forward direction of the operation controlling device by an angle corresponding to the point of view angle.

Synchronization and automation in an itv environment

Abstract: A synchronization mechanism embeds synchronization triggers into a television signal or stream at regular intervals. The triggers include an accurate representation of the time in which the triggers were embedded. A receiving device decodes the triggers and synchronizes its internal timer based on the triggers. In this regard, the receiving device obtains a reference time from the internal timer and computes an offset between the reference time and the trigger time. The computed offset is then applied to the reference time. With the receipt of each new trigger, the application compares the trigger time to a new reference time with the most recently computed offset value applied. If there is any variance between these two values, the application creates a new smoothed offset.

Method for producing a three-dimensional object with resolution enhancement by means of pixel shift

Abstract: The invention relates to a method and device for producing a three-dimensional object by the layer-by-layer hardening of a material, which can be hardened by the action of electromagnetic radiation, by means of mask exposure The mask is generated over an imaging unit with fixed resolution that is formed from a constant number of discrete imaging elements (pixels) that are arranged in a spatially fixed manner to one another In order to enhance the resolution, on the scale of subpixels, along the outer and inner contours of the cross-sectional areas of the object to be produced in a layer-by-layer manner, a multiple exposure is carried out for each layer This consists of a sequence of a number of images in the image/formation plane, these images being offset from one another on the scale of subpixels A separate mask/bitmap is generated for each offset image

A background comparator calibration technique for flash analog-to-digital converters

Abstract: This paper presents a background calibration technique for trimming the input-referred offsets of the comparators in a flash analog-to-digital converter (ADC) without interrupting the ADC's normal operation. For a random-chopping comparator, the polarity of its offset is detected by observing the code density of its comparison results. Binary feedback is then used to digitally adjust the comparator's offset so that the offset is minimized. All calibration procedures are performed in the digital domain. The calibration performance is characterized by the converging speed of the feedback loop and the offset fluctuation due to the disturbance of the ADC's input. These two performance indexes of a background-calibrated comparator (BCC) are determined by three parameters: the probabilistic distribution of the ADC's input, the BCC's offset quantized step size, and the threshold of an internal bilateral peak detector. The offset fluctuation of a BCC can be drastically reduced by employing a windowing mechanism. The use of windowed BCCs in a flash ADC can introduce nonmonotonic-threshold (NMT) effects which include an increase in calibration settling time and an increase in /spl sigma/(V/sub OS/). The use of uncorrelated random chopping for neighboring BCCs can ensure the validity of offset detection and mitigate the NMT effects.

Differential Semblance Velocity Analysis Via Shot Profile Migration

Abstract: Shot profile migration provides a convenient framework for implementation of a differential semblance algorithm for estimation of complex, strongly refracting velocity fields. The objective function minimized in this algorithm may measure either focussing of the image in offset or flatness of the image in (scattering) angle. The gradient of this objective is a by-product of a depth marching scheme, an requires a few extra computations beyond those necessary to produce the prestack data volume. A strongly refracting 2D synthetic data example illustrates the excellent image quality obtainable from model-consistent data. Offset and angle variants behave differently, with more rapid convergence for the offset variant, underlining the importance of a mathematically well posed formulation: in 2D, the angle variant is much less well-conditioned than the offset variant.

Triangular mesh offset for generalized cutter

Abstract: In 3-axis NC (Numerical Control) machining, various cutters are used and the offset compensation for these cutters is important for a gouge free tool path generation. This paper introduces triangular mesh offset method for a generalized cutter defined based on the APT (Automatically Programmed Tools) definition or parametric curve. An offset vector is computed according to the geometry of a cutter and the normal vector of a part surface. A triangular mesh is offset to the CL (Cutter Location) surface by multiple normal vectors of a vertex and the offset vector computation method. A tool path for a generalized cutter is generated on the CL surface, and the machining test shows that the proposed offset method is useful for the NC machining.

Face image correction

Abstract: Method for offset correction of a picture of an object (A) captured by a camera (17) in a handheld radio communication terminal (10), comprising the steps of aiming the camera at the object at a first angle; capturing a front image of the object; storing the front image as a reference image; aiming the camera at the object at a second angle, offset from said first angle; capturing an offset image of the object; and generating, from said offset image, an adjusted front image as captured from said first angle, by using said reference image. The method is typically used for video conference communication, and makes use of an image processing system for generating the adjusted front image.

High speed multiplier

Abstract: A current summing FIR filter can be implemented with multiple differential input stages and variable tail currents. The variable tail currents can be used to appropriately weight the present and previous digital input signals. The weighted outputs of the differential transistor pairs can be summed to provide a filtered output signal. The tail currents can be advantageously varied with variable current sources or by adjustment of the relative widths of the differential transistor pairs. In other embodiments, additional differential pairs can be added to adjust for systematic offset voltages caused by process-induced variations in the structure of circuit devices or to induce a desired offset.

Magnetic security device for securing doors

Abstract: A lock position detection device includes a door locking mechanism having an actuator operable so as to be in a first position causing the door locking mechanism to lock the door or a second position causing the door locking mechanism to unlock the door The device also has a magnetic field detection unit with a magnetic field sensor adapted to output a first signal when the magnetic field sensor detects a magnetic field and a second signal when the magnetic field sensor does not detect a magnetic field, and a wireless transmitter coupled to the magnetic field sensor for transmitting a radio frequency signal based on signals received from the magnetic field sensor A magnet is coupled to the door locking mechanism such that the magnet enters proximity of the magnetic field sensor when the actuator is operated to one of the first position or the second position and causes the magnetic field sensor to output the first signal, and exits proximity of the magnetic field sensor when the actuator is operated to the other of the first position or the second position and causes the magnetic field sensor to output the second signal The lock position detection device also has a magnetic field shield located with respect to the magnetic field sensor so as to prevent a magnetic field originating from the outside region of the door from being detected by the magnetic field sensor The magnet may be coupled to the door locking mechanism such that the magnet enters proximity of the magnetic field sensor at an angle generally perpendicular to the magnetic field sensor when the actuator is operated to one of the first position or the second position and exits proximity of the magnetic field sensor at an angle generally perpendicular to the magnetic field sensor when the actuator is operated to the other of the first position or the second position In particular, when a reed switch is employed as the magnetic field sensor, the magnet is located so as to enter and exit proximity of the magnetic field sensor substantially along (but offset from) a centerline of the reed switch

Using a Blackbody to Calculate Net Longwave Responsivity of Shortwave Solar Pyranometers to Correct for Their Thermal Offset Error during Outdoor Calibration Using the Component Sum Method

Abstract: Thermopile pyranometers’ thermal offset has been recognized since the pyranometer’s inception. This offset is often overlooked or ignored because its magnitude is small compared to the overall solar signal at higher irradiance. With the demand of smaller uncertainty in measuring solar radiation, recent publications have described a renewed interest in this offset, its magnitude, and its effect on solar measurement networks for atmospheric science and solar energy applications. Recently, it was suggested that the magnitude of the pyranometer thermal offset is the same if the pyranometer is shaded or unshaded. Therefore, calibrating a pyranometer using a method known as the shade/unshade method would result in accurate responsivity calculations because the thermal offset error is canceled. When using the component sum method for the pyranometer calibration, the thermal offset error, which is typically negative when the sky is cloudless, does not cancel, resulting in an underestimated shortwave resp...

Method and apparatus for dynamically adjusting quantization offset values

Abstract: An encoding scheme dynamically adjusts a quantization rounding offset parameter used for encoding pictures according to statistics of previously encoded pictures of similar type. A look-up table can be used to store different relative quantization rounding offset parameters associated with different numbers of bits required to encode the pictures. The dynamically adjusted quantization rounding offset scheme achieves better coding performance at high bit rates. In one example, the dynamic quantization offset values are applied to a Uniform-Reconstruction-Quantizer (URQ) used for Laplacian sources.

Equal distance offset approach to representing and process planning for solid freeform fabrication of functionally graded materials

Abstract: This paper deals with the representation and process planning for solid freeform fabrication (SFF) of 3D functionally graded material (FGM) objects. A novel approach of representation and process planning for SFF of FGM objects, termed as equal distance offset (EDO), is proposed. In EDO, a neutral arbitrary 3D CAD model is adaptively sliced into a series of 2D layers. Within each layer, 2D material gradients are designed and represented via dividing the 2D shape into several sub-regions enclosed by iso-composition contours. If needed, the material composition gradient within each of the sub-regions can be further specified by applying the equal distance offset algorithm to each sub-region. Using this approach, an arbitrary-shaped 3D FGM object with linear or non-linear composition gradients can be represented and fabricated via suitable SFF machines.