Showing papers on "Offset (computer science) published in 1998"

3D scan conversion of CSG models into distance volumes

Abstract: A distance volume is a volume dataset where the value stored at each voxel is the shortest distance to the surface of the object being represented by the volume. Distance volumes are a useful representation in a number of computer graphics applications. We present a technique for generating a distance volume with sub-voxel accuracy from one type of geometric model, a constructive solid geometry (CSG) model consisting of superellipsoid primitives. The distance volume is generated in a two step process. The first step calculates the shortest distance to the CSG model at a set of points within a narrow band around the evaluated surface. Additionally, a second set of points, labeled the zero set, which lies on the CSG model's surface are computed. A point in the zero set is associated with each point in the narrow band. Once the narrow band and zero set are calculated, a fast marching method is employed to propagate the shortest distance and closest point information out to the remaining voxels in the volume. Our technique has been used to scan convert a number of CSG models, producing distance volumes which have been utilized in a variety of computer graphics applications, e.g. CSG surface evaluation, offset surface generation, and 3D model morphing.

System and method for real time measurement of detector offset in rotating-patient CT scanner

Abstract: A rotating-patient computed tomography scanning system in which the detector offset is measured in real time for each scan. At least one x-ray--absorbent reference structure is disposed in the field of view, so that a projection of the reference structure is present in every view of the patient. The position of the reference structure can be expressed in terms of the detector offset for each view of the patient. The detector offset for a given image can therefore be determined at the time the image data is obtained. The offset value is used in the data obtained from the current scan to reconstruct images that are free of artifacts that are caused by errors in the detector offset.

Providing force feedback using an interface device including an indexing function

Abstract: A method and apparatus for providing force feedback including an indexing function. A force feedback interface device is coupled to a host computer system displaying a graphical environment. A position of a user-manipulated physical object in a degree of freedom, such as a planar workspace, is sensed by the device, and a user-controlled graphical object is dislplayed on a display screen at a position corresponding to the physical object position. An indexing indication is provided by the user to activate an indexing mode, during which the user-controlled graphical object is displayed at a fixed position on said display screen, regardless of the position of the physical object. The user is able to redefine an offset between the position of the physical object and the position of tile user-controlled graphical object during the indexing mode. A safety switch can be used to activate the indexing mode.

Offset reduction in Hall devices by continuous spinning current method

Abstract: A novel method for dynamic offset compensation in a Hall plate is presented. The continuous spinning current method is based on minimalsize four-contact Hall devices and, therefore, the lowest possible offset resulting from material inhomogeneities is achieved. A continuous spinning current vector is generated in the device by spatially superimposing two periodic biasing currents. The resulting voltages allow the constant Hall voltage to be separated from the periodic offset voltage. Remaining offsets are below 10 μT, which corresponds to fractions of the earth's magnetic field.

Surgical instrument with offset jaw actuator

Abstract: A tool for grasping or cutting with an offset jaw actuator is shown. The offset provides a consistent width to the actuator discouraging buckling under heavy loading situations. The offset also provides for greater contact area between the actuator and inner tip. The interface of the actuator with the inner tip is machined into the inner tip from the side resulting in an instrument that is easier and cheaper to manufacture and clean while retaining maximum strength for cutting or grasping.

Finger assignment in a CDMA rake receiver

Abstract: A method and apparatus of assigning fingers in a rake receiver for incorporation in a receiver of a CDMA communications system is disclosed herein. The method includes measuring the multipath profile of a received spread-spectrum radio-frequency (RF) signal to obtain a sequence of measurements, identifying the best candidate path of the RF signal to demodulate by determining which measurement within the sequence has the highest signal strength, deriving a timing offset for the best candidate path as a function of the measurement for the best candidate path and its adjacent measurements, and assigning a finger processing element to the best candidate path using the derived timing offset. The measurements are taken using a searcher having a predetermined timing resolution (e.g., ½ chip), and the resolution of the timing offset is higher (e.g., ⅛ chip). The best candidate path to demodulate is identified using the measurement having the highest amplitude or correlation function. The function used to derive the timing offset is a quadratic passing through the measurement for the best candidate path and adjacent measurements. A correction factor can be applied to the estimated timing offset to correct for non-quadratic multipath profiles. The assignment can be made for an available finger, or a finger can be re-assigned where the best candidate path is better than a path currently being demodulated. This approach can also be used to update and instantaneously adjust the timing of fingers to track on-time samples of the received multipaths during operation of the rake receiver.

The equivalent offset method of prestack time migration

Abstract: A prestack time migration is presented that is simple, efficient, and provides detailed velocity information. It is based on Kirchhoff prestack time migration and can be applied to both 2-D and 3-D data. The method is divided into two steps: the first is a gathering process that forms common scatterpoint (CSP) gathers; the second is a focusing process that applies a simplified Kirchhoff migration on the CSP gathers, and consists of scaling, filtering, normal moveout (NMO) correction, and stacking. A key concept of the method is a reformulation of the double square‐root equation (of source‐scatterpoint‐receiver traveltimes) into a single square root. The single square root uses an equivalent offset that is the surface distance from the scatterpoint to a colocated source and receiver. Input samples are mapped into offset bins of a CSP gather, without time shifting, to an offset defined by the equivalent offset. The single square‐root reformulation gathers scattered energy to hyperbolic paths on the appropri...

View offset estimation for steroscopic video coding

Abstract: In a stereoscopic video transmission system, where an enhancement layer image is disparity predicted using a lower layer images, the lower layer image is made to more closely match the enhancement layer image by shifting the lower layer image to the right to compensate for inter-ocular camera lens separation. The motion vector search range for disparity prediction is reduced to improve coding efficiency. At an encoder, the optimal offset, x, between the enhancement layer image and the lower layer image is determined according to either a minimum mean error or a minimum mean squared error between the enhancement and lower layer images. The offset x is bounded by an offset search range X. The x rightmost pixel columns of the lower layer image are deleted, and the x leftmost columns of the lower layer image are padded to effectively shift the lower layer image to the right by x pixels to obtain the reference image for use in disparity predicting the enhancement layer image. For arbitrarily shaped images such as VOPs within a frame, the leftmost portion is deleted and the rightmost portion is padded. At a decoder, the offset value x is recovered if available and used to reconstruct the reference frame.

Method and apparatus for calibrating azimuth boresight in a radar system

Abstract: A method and apparatus for calibrating azimuth boresight in a radar system. Antenna boresight misalignment can cause radar systems to inaccurately determine the position of targets relative to a platform vehicle. These errors can be corrected by detecting and accurately measuring a boresight offset angle defined as the angle between the radar antenna boresight and the direction of travel of the host platform vehicle. Several antenna boresight calibration techniques are described. A first technique calculates the boresight offset angle by obtaining target range and azimuth angle measurements at two instants in time. The boresight offset angle is determined by the geometric relationship of the offset angle, target range and azimuth values obtained at two successive time instants. A refined approach obtains target range and azimuth values at several successive time instants, calculating interim boresight offset angles at each time instant. The boresight offset angle is computed by averaging the interim boresight offset angles. In second and third calibration techniques, the boresight offset angle is estimated from the azimuth of qualified calibration targets that are substantially aligned with the host vehicle's heading. Several restrictions are imposed upon the potential calibration targets to suppress the erroneous qualification of adjacent vehicle traffic. In accordance with one embodiment of the present invention, the calibration techniques are implemented by software instructions executed by a microprocessor within the radar system. Once the boresight offset angle is detected and calculated, it can be used to calibrate the antenna boresight using either a mathematical or physical calibration approach.

A uniform optimization technique for offset assignment problems

Abstract: A number of different algorithms for optimized offset assignment in DSP code generation have been developed recently. These algorithms aim at constructing a layout of local variables in memory, such that the addresses of variables can be computed efficiently in most cases. This is achieved by maximizing the use of auto-increment operations on address registers. However, the algorithms published in previous work only consider special cases of offset assignment problems, characterized by fixed parameters such as register file sizes and auto-increment ranges. In contrast, this paper presents a genetic optimization technique capable of simultaneously handling arbitrary register file sizes and auto-increment ranges. Moreover, this technique is the first that integrates the allocation of modify registers into offset assignment. Experimental evaluation indicates a significant improvement in the quality of constructed offset assignments, as compared to previous work.

Equalizer for use in multi-carrier modulation systems

Abstract: The present invention provides an optimal procedure for determining in the time domain equalizer coefficients for an equalizer, where the equalizer compensates for the effects of the communications channel on the transmitted signal. A unit pulse is transmitted over the communications channel, and a channel impulse response is estimated from the received signal. A cost function establishes a mean-square error associated with the estimated channel impulse response as compared to a desired impulse response signal. The value of the cost function varies based upon an offset value between the estimated channel impulse response and an equalized channel impulse response. Values of the cost function are determined for different offsets, and the offset that produces the smallest cost function value (corresponding to the minimum mean-square error) is selected. The optimal equalizer coefficients are then calculated using the selected offset and the established cost function. In a preferred embodiment, the invention is applied to multicarrier modulation systems. Moreover, the cost function is defined as a krakovian function that depends on the offset value. That krakovian function includes a first krakovian which uses the channel impulse response and a second krakovian which uses the autocorrelation of the channel impulse response. Using the first and second krakovians and the selected offset corresponding to the minimal value of the established cost function, the optimal equalizer coefficients are determined in a straightforward, one step calculation.

Method and apparatus for generating an alignment control vector

Abstract: The data processing system loads three input operands, including two input vectors and a control vector, into vector registers and performs a permutation of the two input vectors as specified by the control vector, and further stores the result of the operation as the output operand in an output register. The control vector consists of sixteen indices, each uniquely identifying a single byte of input data in either of the input registers, and can be specified in the operational code or be the result of a computation previously performed within the vector registers. The control vector is specified by calculating the offset of a selected vector element of the input vector relative to a base address of the input vector and loading each element with an index equal to the relative offset. Alternatively, the generation of the alignment vector is made by performing a look-up within a look-up table. For additional loads from the same vector, the control vector does not change, since the alignment shift amount of the vector from an address boundary does not change. A permutation instruction can then be executed to load and shift the data to realign it in the output register at the vector boundary.

Multiple link robot arm system implemented with offset end effectors to provide extended reach and enhanced throughput

Abstract: Two multiple link robot arms (10) are mounted to a torso link (11), and each of them includes an offset hand (30) and two motors (50, 52) capable of independent operation that provides movement of the offset hand along along combinations of angular, radial, linear, and curvilinear paths. The first motor rotates a forearm (22) about an elbow axis (24), and the second motor rotates an upper arm (14) about a shoulder axis (16). A motor controller (54) controls the first and second motors in two operational states that respectively enable linear extension or retraction of the robot arm radial to the shoulder axis and enable angular displacement of the hand about the shoulder axis. A distal end (34) of each offset hand is offset such that during first operational state motion, the distal end follows paths parallel to lines radial to the shoulder axis. The offset distance (240) is set so that when properly rotated in the second operational state, both offset hands can follow a common hand extension line (44) that is a perpendicular bisector between the shoulder axes of the robot arms. This allows specimens (206) retrieved by either offset hand to be placed on a processing station (208) located along the hand extension line.

Method and system for cost computation of spelling suggestions and automatic replacement

Abstract: Suggestions may be ordered by their associated costs so that the best suggestions may be displayed to the user and so that, in certain instances, a misspelled word entered by the user may be automatically replaced with a suggestion. To begin generating suggestions and costs, the user input and dictionary word (path of a trie) are considered in parallel. State variables are maintained such as the current cost of the dictionary word and the number of letter positions that have gone unmatched up to the current pointer position, also referred to as the offset. If the offset is zero and the next letters match, the cost associated with the dictionary word is maintained equal to zero. However, if the offset is zero and the next letters of the user input and the dictionary word do not match, then a cost for the dictionary word may not yet be determined. Otherwise, if the offset is greater than zero, possible paths in the trie and associated costs for the paths are determined. If a cost or multiple costs are determined, then the cost(s) is applied to the dictionary word, the offset is set to zero, and the matching process continues. If a cost can not be determined, then the offset is incremented by one and the matching process continues. Dictionary words (paths) are eliminated from consideration when their associated costs become too high. At the end of the matching method, the dictionary word (path) with the lowest cost is typically the best suggestion to replace the misspelled word.

Pilot PN offset assigning method for digital mobile telecommunications system

Abstract: There is provided a method for assigning a pilot PN(PseudoNoise) offset to a base station in a digital mobile telecommunications system. In the pilot PN offset assigning method, a single cluster is divided into a plurality of subclusters, and a plurality of general base stations and reserved base stations, each having a plurality of sectors, are arranged in each of the subclusters. Then, a pilot PN offset is assigned to each sector, such that the PN offset difference between a sector and a next sector in the same base station is equal to a pilot increment times the number of subclusters in the cluster according to sector numbers, the PN offset difference between the same sectors in corresponding base stations under different subclusters is equal to the pilot increment, and the PN offset difference between the same sectors in a current base station and the next base station under an identical subcluster is equal to the number of subclusters in the cluster times the number of sectors in a base station×the pilot increment.

Method and apparatus for handoff within a communication system

Abstract: In a communication system (100) where a remote unit is given a time offset for a base station (102) and hands off to the base station (102) if the remote unit (113) can acquire the base station within a time window surrounding the time offset, a remote unit (113) utilizes the time offset of each base station (supplied by a serving base station (101) via downlink communication signal (116)) and searches for neighboring base stations within the time window surrounding its PN offset. The time window surrounding an individual base station's PN offset is allowed to vary depending upon whether the communication system (100) is time synchronized. In particular, a base station (101) supplies the remote unit (113) with an indication that the communication system (100) is operating in a synchronized or an unsynchronized mode, and the remote unit (113) varies the time window (search window) accordingly.

A method and system for accessing carrier data

Abstract: The invention is a method and system of loading a data object representative of carrier data and possible command structures, which can be identified by both name and date fields characteristics, into a Data Access System of a carrier management system. The method begins with receiving a request for an object and then determining whether or not the object resides in a first data table which is indicative of a plurality of characteristics of the object. If the object is not resident in the first data table, then the system assigns an initial time stamp and a permanence value to the object. Additionally, the method and system must determine the memory space, in the Data Access System, required for storing the object. De-referenced objects are removed from the memory until space is available that is greater than or equal to the memory requirement of the object. After memory is allocated to the object, the object is then loaded into the memory for use within the carrier management system. A directory table is then established for the object. The directory table includes: an object name; a set of associated data; and, an object table data pointer. The associated data includes an effective date; an expiration date; and, the modification status of the file.

Synchronizer and method therefor and communications system incorporating same

Abstract: Users or subscribers (36) of a spread spectrum synchronous communications system provide signals to the central station or base unit (30) of that system, and receive signals therefrom. Proper synchronization among those users (and their signals) is needed to ensure proper operation of the system. To ensure proper synchronization among those users, the signal produced by each user is checked for presence and amount of any offset error. This is accomplished by using three despreaders (42, 44 and 46) for the signal for each user. For one such user (36), each such despreader for that user receives the spreading code (50) for that user. However, the spreading code as received by any one such despreader is time delayed (52 and 54) with respect to the spreading code (50) as received by the other two despreaders. Each such despreader receives the spreading code with different amount of delay imposed on that spreading code. The outputs of the three despreaders (42, 44 and 46) are digitally combined (66), or compared, to produce the offset estimate for that user (70). To reduce noise effects, the offset estimate is averaged over a predetermined time duration; alternatively, such averaging can be performed on the outputs of the despreaders, or at some intermediate processing step. The offset estimate is sent to the user, to be used to correct synchronization of that user. Offset estimates that are too small to be useful are squelched and are not so sent to the user, to reduce channel usage and thereby save bandwidth.

Magnetoresistive type position detecting device

Abstract: In a position detecting device for a moving object, such as a camshaft gear, having ridges and valleys, magnetoresistive elements are disposed in positions offset in the rotation direction of the moving object from the magnetic center of a bias magnetic field projected by a bias magnet. The direction of the bias magnetic field is different when the moving object is in a ridge position from when it is in a valley position. A mid-point potential of the MREs is taken as the output of an MRE bridge to obtain an output value which is different when the moving object is in the ridge position from when it is in the valley position. It is thus possible to distinguish between the ridge position and the valley position of the moving object.

Polygon offsetting using a Voronoi diagram and two stacks

Abstract: The generation of the trimmed offset of a simple polygon is a conceptually simple but important and computationally non-trivial geometric problem for many applications. This article presents a linear time algorithm to compute a trimmed offset of a simple polygon consisting of arcs as well as line segments in a plane. Assuming that a Voronoi diagram of the polygon is available, the algorithm uses two stacks: T-stack and C-stack. The T-stack contains intersections between an offset and Voronoi edges, and the C-stack contains an offset chain which is a part of the trimmed offset. The contents of both stacks are pushed into and popped from the stacks in a synchronized fashion depending on the events that occur during the offsetting process.

Compensation algorithm for initializing yaw rate sensor's zero point offset

Abstract: When a motor vehicle is not in motion, an algorithm for establishing the initial zero point offset values for a yaw rate sensor as may be used in motor vehicle software control systems. The initial values are the manufactured values and are downloaded into the vehicle ECU at the time of the manufacture of the ECU. When the vehicle is waken at the vehicle assembly and the ignition is first turned on, the initial actual value of the zero point offset is stored both as a maximum and minimum value. At subsequent adjusting times when the vehicle is not moving, but the ignition is on, the spread between the maximum and minimum values are checked. If the spread becomes greater than a desired predetermined spread, the value, be it the maximum or minimum value reflects the measured value and the other value is adjusted to be within the desired spread. When the ignition is turned off and the vehicle is not moving, the zero point offset maximum and minimum values are stored in memory. The mean value is calculated to provide the new zero point offset value of the yaw rate sensor when the vehicle ignition is then turned on and the vehicle is not moving.

Method and apparatus for joint timing synchronization and frequency offset estimation

Abstract: A burst analyzer is useful in a digital communication system in which a signal burst has a plurality of reference segments distributed within the signal burst for transmission of a plurality of reference signals. The burst analyzer includes a filter that compares the received signal, for each reference segment thereof, with each reference signal offset by one of a plurality of time offsets to generate correlation data. The burst analyzer then determines, for each reference segment of the signal burst, a maximum correlation value from the correlation data for each time offset. Then the burst analyzer determines the time offset at which a sum of the maximum correlation values, over the plurality of reference segments, is a maximum. The burst analyzer jointly generates a frequency domain representation of the correlation data associated with the time offset at which the maximum correlation sum is a maximum, and then determines a frequency at which the frequency domain representation is a maximum.

Data sharing between system using different data storage formats

Abstract: Disclosed is a system, typically implemented in a storage controller, for extracting data from a device storing data in a first format, such as the count-key-data (CKD) format. The first format is comprised of a plurality of tracks. Each track has at least one data area and each data area is comprised of at least one addressable block of data. A request from a host system for an address of a block of data in a second data format, such as the Fixed Block Architecture (FBA) format, is received. The system calculates a byte displacement value for the requested address. A data area in a track in the device having a byte displacement value less than the byte displacement value for the requested address is located. A byte location offset is then determined by subtracting the byte displacement value for the located data area from the byte displacement value for the requested address. The system then determines a location in the located data area of a block of data at the byte location offset. The system then provides the host system with the located block of data.

Computer input device with inclination sensors

Abstract: A computer input device includes a user manipulable portion having a first primary axis of motion. An inclination sensor has a first sensing axis. The inclination sensor is coupled to the user manipulable portion such that the first sensing axis is disposed at a first offset angle relative to the first primary access of motion. An output component is coupled to the inclination sensor and provides output information indicative of sensed inclination.

Method and apparatus to compensate for dark current in an imaging device

Abstract: An imaging device includes a compensation circuit for reducing an effect of dark current generated during operation. The compensation circuit calculates an initial dark current offset value using optically dark regions of a photo sensitive array. The compensation circuit also automatically adjusts the initial dark current offset value as output signals from successive rows of the photo sensitive array are transferred. The compensation circuit can calculate the initial dark current offset value each time an image is captured, thereby compensating for variables such as temperature.

High offset bits with super-abrasive cutters

Abstract: A roller bit is provided having super-abrasive inserts on cutting portions to assure that the bit will maintain cutting efficiency. In the described exemplary bits, the axes of the roller cones are also offset by a significant or “high offset” amount from the central longitudinal axis of the bit, thereby providing for increased shearing and grinding action by the bit. The use of high offset in combination with super-abrasive inserts provides for optimal bit cutting designs which provide increases in ROP while preserving the bit's ability to hold gage and remain durable to achieve acceptable footage. Minimum high offsets and preferred high offsets are described for various bit sizes, designs and nomenclatures, including milled tooth bits and insert-type bits designed for use in soft-through-medium formation hardnesses as well as formations with greater hardnesses.

Determining the actual class of an object at run time

Abstract: A dynamic down cast or cross cast is performed at run time within an object-oriented programming language such as C++. The compiler generates data structures during a compile; at run time a routine in the language support library accesses the generated data structures in order to perform the dynamic cast. Class structure information is provided in a size that varies linearly as the total number of classes in the class hierarchy. Cryptographic hashing of class names is used to provide uniqueness. The dynamic cast addresses complications in C++ due to "virtual" and "nonvirtual" inheritance. A run time type identification (RTTI) data structure is created at compile time. An offset within an object description is calculated for each sub-object of the object. Those virtual base classes that are duplicates are skipped producing a data structure that may be searched linearly as the number of classes in the hierarchy. An identifier for each sub-object is stored in the data structure along with its offset. Each virtual table also stores the offset of its corresponding sub-object. A cast operation is performed at run time using the RTTI data structure. The static type object pointer is used to access the object through a particular sub-object. The virtual table associated with the sub-object is used to access the RTTI data structure. The data structure is searched for the target type, and the offset associated with the target type is combined with the offset from the virtual table to adjust the object pointer to cast it to the target type.

Advertising step systems

Abstract: An advertising system for displaying images on a series of offset stationary vertical surfaces is disclosed. The advertising system includes a plurality of substrates, each having a layer of printed indicia on a surface thereof in combination with the series of offset stationary vertical surfaces to provide a desired overall visual image.

An automatic offset compensation technique applicable to existing operational amplifier core cell

Abstract: An automatic offset compensation scheme for two-stage operational amplifiers is described. The presented technique can be applied to an existing OA core cell without modifying its design. Offset voltage is reduced by digitally adjusting the resulting offset current at the node between the first and second OA stages. A background calibration is achieved by using a ping-pong structure that improves the temperature stability and an on-demand calibration is also provided. The proposed circuit has been fabricated in a 0.7 /spl mu/m digital CMOS technology. The measured input offset voltage of the test circuits are less than /spl plusmn/200 /spl mu/V.