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792 results about "Time error" patented technology

System and method for autonomously generating heterogeneous data source interoperability bridges based on semantic modeling derived from self adapting ontology

A system, including software components, that efficiently and dynamically analyzes changes to data sources, including application programs, within an integration environment and simultaneously re-codes dynamic adapters between the data sources is disclosed. The system also monitors at least two of said data sources to detect similarities within the data structures of said data sources and generates new dynamic adapters to integrate said at least two of said data sources. The system also provides real time error validation of dynamic adapters as well as performance optimization of newly created dynamic adapters that have been generated under changing environmental conditions.
Owner:COMPASS AL INC +1

Transmitting and receiving apparatus and method in adaptive array antenna system capable of real-time error calibration

Disclosed are a transmitting and receiving apparatus and method in an adaptive array antenna system capable of real-time calibration. Transfer functions in the transmitting and receiving apparatus are estimated by injecting a calibration signal to each of transmit and receive channels and analyzing the signals that has passed through the transmit and receive channels. An RF CW sinusoidal signal of a single frequency can be used as the calibration signal to simplify a process of signal processing in a baseband. In addition, in the calibration of the receiving apparatus, gains of all receive channels are controlled using an identical signal. Thus, a relative transfer function characteristic of the receive channels is constant irrespective of the gains of the receivers.
Owner:ELECTRONICS & TELECOMM RES INST

Method for realizing accurate time synchronization by utilizing IEEE1588 protocol

The invention discloses a method for realizing accurate time synchronization by utilizing an IEEE1588 protocol, comprising the following steps: a) a Sync message is transmitted to a slave clock by a master clock, a transmission timestamp TM1 and a receiving timestamp TS1 of the message are acquired by the slave clock; b) a Delay_Req message is transmitted to the master clock by the slave clock, and a transmission timestamp TM2 and a receiving timestamp TS2 of the message are acquired by the slave clock; c) transmission delay and time offset are calculated by the slave clock according to the timestamp; and d) the calculated Offset is corrected in a fixed adjustment frequency in the correction time by the slave clock. The invention realizes accurate time synchronization, calculates time offset and self-compensate through the slave time clock in a packet based network, and leads the slave clock to lock the master clock whether in clock frequency or on the clock time in a shorter time, and occupies little hardware resources.
Owner:ZHEJIANG UNIV

Synchronization of seismic data acquisition systems

A network distributed seismic data acquisition system comprises seismic receivers connected to remote acquisition modules, receiver lines, line tap units, base lines, a central recording system and a seismic source event generation unit synchronized to a master clock. One or more high precision clocks is added to the network to correct for timing uncertainty associated with propagation of commands through the network. Seismic receivers and seismic sources are thereby synchronized with greater accuracy than otherwise possible. Timing errors that interfere with the processing of the seismic recordings are greatly reduced, thus enabling an improvement in subsurface geologic imaging.
Owner:INOVA SYST CORP

High reliability memory module with a fault tolerant address and command bus

A high reliability dual inline memory module with a fault tolerant address and command bus for use in a server. The memory module is a card approximately 151.35 mm or 5.97 inches long provided with about a plurality of contacts of which some are redundant, a plurality of DRAMs, a phase lock loop, a 2 or 32K bit serial EE PROM and a 28 bit and a 1 to 2 register having error correction code (ECC), parity checking, a multi-byte fault reporting circuitry for reading via an independent bus, and real time error lines for determining and reporting both correctable errors and uncorrectable error conditions coupled to the server's memory interface chip and memory controller or processor such that the memory controller sends address and command information to the register via address / command lines together with check bits for error correction purposes to the ECC / Parity register. By providing the module with a fault tolerant address and command bus fault-tolerance and self-healing aspects necessary for autonomic computing systems compatible with industry-standards is realized. The memory module corrects single bit errors on the command or address bus and permits continuous memory operation independent of the existence of these errors and can determine any double bit error condition. The redundant contacts on the module prevents what would otherwise be single points of failure.
Owner:IBM CORP

Time error estimation for data symbols

The invention relates to a method and a system for estimating a symbol time error in a broadband transmission system, comprising: determination a timing error signal of an input-signal of a discrete Fourier-transformation block (5) in a data symbol stream on the basis of intersymbol correlation using a predetermined period in each received symbol, selecting as a predetermined period a number of samples of different useful data parts of a symbol, determining the time error value (ε) based on the intersymbol interference of the selected samples of the different parts of said symbol.
Owner:ENTROPIC COMM INC

System and method for GPS navigation before signal bit synchronization

InactiveUS7064709B1Not substantially improve time-to-first-fixTime-to-first-fix is substantially reducedPosition fixationRadio transmissionTime errorTime to first fix
A system and method are provided for determining a position of a Global Positioning System (GPS) receiver prior to bit and frame synchronization. As such, the time-to-first-fix is substantially reduced. More specifically, pseudoranges to five GPS satellites are measured by correlating locally generated Pseudo-Random Number (PRN) codes with signals received from the GPS satellites. After correlation, the pseudorange measurements are correct with an unknown integer number of milliseconds error, which is different for each of the pseudorange measurements. Using the measurements of the pseudoranges and a mathematical model where each of the pseudorange measurements is forced to have a common channel time error, the user position and the common channel time error are determined prior to bit and frame synchronization.
Owner:QUALCOMM INC

Drive control unit, drive circuit and drive control method of display substrate

ActiveCN103198803AEnsure consistencyCompensate for charging time errorStatic indicating devicesTime errorTime schedule
The invention discloses a drive control unit, a drive circuit and a drive control method of a display substrate. The drive control unit comprises a time schedule controller and a delay controller, wherein time schedule controller sends sequential control signals to the delay controller, the delay controller is used for regulating the sequential control signals according to impedance of a drive signal wire connected with pixel points of the display substrate, and real charge duration of the pixel points is within a preset duration range. According to the drive control unit, the drive circuit and the drive control method, the sequential control signals of the pixel points are changed according to positions of the pixel points on a liquid crystal panel, the sequential control signals of pixel points in different positions are different, charge time errors caused by signal wire delay are compensated by the different sequential control signals, and consistency of charge effects of the pixel points in the different positions of the liquid crystal panel is guaranteed.
Owner:BOE TECH GRP CO LTD +1

System and method for compensating timing error using pilot symbol in OFDM/CDMA communication system

A timing error compensation system in an OFMD / CDMA communication system includes an analog-to-digital converter for converting an OFDM signal, comprised of a data symbol stream in which a pilot symbol is inserted at intervals of a prescribed number of data symbols, received from a transmitter, to a digital OFDM symbol stream by prescribed sampling synchronization, a guard interval remover for removing a guard interval inserted in the OFDM symbol by prescribed frame synchronization, and a fast Fourier transform (FFT) device for performing fast Fourier transform on the guard interval-removed OFDM symbol and outputting a data symbol stream. In the time error compensation system, a pilot symbol detector receives the data symbol stream and detects the pilot symbols inserted in the data symbol stream at prescribed intervals. A timing compensator determines a linear phase difference line for the detected pilot symbol, generates a timing error estimation signal according to the determined linear phase difference line, and provides the timing error estimation signal to the analog-to-digital converter and the guard interval remover so as to determine the sampling synchronization and the frame synchronization.
Owner:SAMSUNG ELECTRONICS CO LTD

Digit controlled machine tool real time error compensator for off centering machine tool exterior coordinate system

InactiveCN1631614AEasy to useCompensation implementation is convenient and simpleAutomatic control devicesFeeding apparatusTime errorNumerical control
The invention is a digital lathe error real-time compensator based on lathe external coordinate system offset. It includes calculating and processing module, CNC port and motion control module, sensor and transmitting module. The sensor and transmitting module is linked with calculating and processing module by data cables. The calculating and processing module is linked with CNC port and motion control module by data cables and communication protocol and acquires the input and output, saving, calculating of the signals. The CNC port and motion control module offsets the lathe external coordinate system to extra move the lathe by service system according to compensating value received as signals outputted from the calculating and processing module. The sensor and transmitting module gathers the temperature and heat error signals of the lathe and transmits to processing module after processed. The calculating and processing module may links with the computer so to acquire the command and data transferring and saving between the superior and inferior machine. The invention is of simple structure, handily use, low cost, highly real-time, more efficient compensation with a bright industrializing foreground.
Owner:SHANGHAI JIAO TONG UNIV

Self-adoptive correcting device of mismatch error of time-interleaved analog-digital converter

InactiveCN101888247AAvoid problems that are difficult to convert to hardware circuitsThere is no problem of implementation deviationAnalogue-digital convertersAnalogue/digital conversion calibration/testingTime errorDigital down converter
The invention discloses a self-adoptive correcting device of mismatch error of time-interleaved analog-digital converter, comprising an M channel TIADC, a signal recombination, a digital reference signal memorizer, a simulated reference signal generator, a self-adaptive reconstruction filter bank, a clock generation circuit and a subtraction device. Signals after passages are reconstructed are used to correct each passage instead of single correction on each passage, thereby solving the problem that when an input signal bandwidth is larger than the Nyquist frequency of each passage ADC, the time error can not be corrected due to aliasing. Each self-adoptive reconstruction filter is divided into a plurality of sub-filters for concurrent working, thereby not improving the requirement of thetreatment speed for a self-adoptive correcting filter while realizing the effect of signal recombination and ensuring the practicability of the hardware of the structure of the invention. A digital reference signal is internally installed in the device and is taken as a target to carry out the self-adoptive correction, pre-measuring or calculating a passage mismatch error is not needed, and the source of the error is not needed to be discriminated so that various mismatch errors can be corrected.
Owner:BEIJING UNIV OF TECH

Audio synchronization output method and system

The invention discloses an audio synchronization output method and a system. The system comprises a control terminal, a media server and a plurality of play terminals which are accessed to a local area network. The method comprises the steps that S1, the control terminal selects one play terminal from the local area network to serve as a reference terminal, and sends a synchronization instruction to the reference terminal; S2, the reference terminal downloads specified audio information from the media server, decodes the audio information for generating digital audio information, and sends a clock synchronization coordination instruction to the specified play terminals, and the clock synchronization coordination instruction enables the play terminals to send clock synchronization coordination instruction return values to the reference terminal, and synchronizes a clock to the reference time; and S3, the reference terminal sends the digital audio information to the play terminals feeding back the clock synchronization coordination instruction return values within the required time for synchronously playing the digital audio information on the play terminals. Play time errors among the play terminals are reduced, and the quality of an audio is guaranteed.
Owner:SHENZHEN AIRSMART TECH CO LTD

System and method for testing satellite-ground time delay and onboard time errors

The invention discloses a system and method for testing satellite-ground time delay and onboard time errors. The method comprises the steps of: firstly, acquiring format pulses generated based on onboard telemetering, and recording GPS (Global Position System) time generated by the format pulses; and then, demodulating to generate telemetering format pulses by using a special testing device and recording the GPS time for demodulating the format pulses. The satellite-ground time delay can be calculated by means of two telemetering format pulses read by an oscilloscope, and can also be acquired by calculating a difference between two GPS time through a program. A 1553B bus monitoring module is used for monitoring air time codes of a center computer of a satellite on a bus, a GPS data receiving processing module is used for acquiring ground GPS time, and a master control module is used for calculating difference values between the air time codes and the ground GPS time so as to acquire the onboard time errors. The satellite-ground time delay measurement precision is not less than 200us, and the onboard time measurement precision is not less than 100us.
Owner:CHINA ACADEMY OF SPACE TECHNOLOGY

Hold time error correction method and correction program for integrated circuits

A hold time error list, having for each hold time error path a hold time error value satisfying plural timing constraints, and more specifically a maximum hold time error value for each of timing constraints, as well as a setup time margin map allocating to path a setup time margin satisfying plural timing constraints for each setup time error path, and more specifically minimum value of setup time margins for the same path for each timing constraint, are generated. Also, referring to this setup time margin map, delay buffers, which reduces or eliminates hold time error of hold error list, and a delay of which is within the range of delay amounts and positions equal to or lower than the setup time margin, are inserted. Referring to the setup time margin map, it is possible to insert delay buffer to correct hold time error without causing new setup time errors.
Owner:SOCIONEXT INC

System and method for detecting power system conditions

Provided is a system and method for detecting a power system condition of a power system. The system includes at least a first and second intelligent electronic device (IED) operatively coupled to the power system at respective first and second power system locations. Each IED is configured to calculate a measured time value based on a frequency dependant parameter such as a secondary voltage signal at their respective locations, to compare the measured time value to a reference time value to form a time error, and to transmit the time error. The system further includes a third IED configured to compare respective time errors received from the first and second IEDs to form a time differential error, to map the time differential error back to their power system locations, and compare the time differential error to a predetermined threshold to determine the power system condition.
Owner:SCHWEITZER ENGINEERING LABORATORIES

Direct-current power distribution network protection method based on voltage characteristic traveling wave similarity measurement

ActiveCN108923398APreserve timing featuresCompensate for transmission delayEmergency protective circuit arrangementsTime errorFault tolerance
The invention discloses a direct-current power distribution network protection method based on voltage characteristic traveling wave similarity measurement. According to the method, the transient voltage currents at the two ends of a line after a direct-current fault occurs are subjected to high-frequency sampling, and are converted into line mode voltage forward traveling wave of one side of a protection area and line mode voltage inversion traveling wave of the opposite side; and based on traveling wave refraction reflection and polarity difference of intra-region and extra-region faults offorward inversion traveling wave at the two ends caused by mismatching of impedance of fault points, the similarity between the two waveforms is reflected by utilizing a globally optimal neighborhooddiffusion compatible dynamic matching similarity measure algorithm, so that the intra-region and extra-region faults can be reliably identified. According to the method, the traveling wave transmission delay and the time-to-time error can be compensated, influence from the sampling frequency deviation at the two ends, data missing and damage and the like is not caused easily, the fault tolerance is relatively high, the detection speed is high, and the power supply operation of the direct-current power distribution network is more reliable.
Owner:ELECTRIC POWER RES INST OF STATE GRID ZHEJIANG ELECTRIC POWER COMAPNY +1

Multi-sensor combined navigation time synchronizing system based on field programmable gate array (FPGA)

The invention relates to a multi-sensor combined navigation time synchronizing system based on a field programmable gate array (FPGA). The multi-sensor combined navigation time synchronizing system comprises a global navigation satellite system (GNSS) receiver, a navigation sensor group, an FPGA module and a combined navigation computer, wherein the GNSS receiver and the navigation sensor group are connected with the FPGA module respectively; the GNSS receiver and the FPGA module are connected with the combined navigation computer respectively; the FPGA module is used for decoding output data of the GNSS receiver to obtain receiver time, adding the receiver time, as a time tag, into measurement data of the navigation sensor group, and performing coding to obtain synchronous measurement data; the combined navigation computer is used for processing the received synchronous measurement data and the output data of the GNSS receiver, and outputting a final navigation positioning result. Compared with the prior art, the multi-sensor combined navigation time synchronizing system has the advantages that time errors of measurement data of navigation sensors can be effectively eliminated, and high-accuracy combined navigation in a high-speed environment is realized.
Owner:靳文瑞 +1

Honing Feed System Having Full Control of Feed Force, Rate, and Position and Method of Operation of the Same

The feed system (30) for a honing machine (10) provides a capability to dynamically correct in real time errors in bore size inferred arising from variations in feed force, and a method of operation of the same. The system (10) allows a user to select between rate and force controlled honing modes, which provides one or more of the advantages of both modes. The system provides capabilities for automatic rapid automatic bore wall detection, compensation for elasticity of elements of the feed system (30) and honing tool (14), and automatic tool protection. The system is automatically operable using feed force, feed rate and positional information for honing a work piece (20) to one or more target parameters, such as one or more in-process sizes and a final size.
Owner:SUNNEN PROD

Method for real-time correcting error of multi-channel high-speed parallel alternative acquisition system

The invention discloses a method for real-time correcting error of a multi-channel high-speed parallel alternative acquisition system, which comprises the following steps: in correction, inputting direct current correction signals of different voltages, acquiring a quantization value of each ADC and performing correction point by point to obtain errors point by point and form an error matrix; in measurement, inputting a signal to be measured and performing sampling at time alternating, acquiring quantization values and searching a table in the error matrix, deducting corresponding error value from the quantization values respectively to obtain corrected actual quantization values; and then, rearranging the corrected quantization values according a time phase relationship; converting the rearranged and corrected quantization values into acquisition data for output; and performing low-pass filter; and filtering time-base deviation error spectral line so as to finish the correction of a time error. Compared with the prior art, the method has the advantages that: the deviation and a gain error can be corrected at the same time; and a table searching operation is a corresponding relationship operation of which the process is simple and the calculation amount is small. A low-pass digital filter is very easy to be implemented in a DSP processor and the operation rate is fast so that the efficiency of the time error correction is improved greatly.
Owner:UNIV OF ELECTRONICS SCI & TECH OF CHINA

Joint estimation and real-time correction method for channel error of TIADC system

The invention discloses a joint estimation and real-time correction method for channel error of a time-interleaved ADC (TIADC) system. The method for implementing joint estimation comprises the steps of: sampling a single-tone signal with input frequency of f0 to obtain a sampling sequence xk(n) of various channels of the system, wherein k=0, 1, L M-1; performing fast Fourier transform (FFT) on sampling data x(n) which is reduced into a single-tone signal after the split joint; and in an FFT result, selecting a value FAk at the position where the frequency is 1fs / M+ / -f0,1=0, 1L M-1 and selecting a value FBk at the position where the frequency is 1fs / M,1=0, 1L M-1 to perform inverse fast Fourier transform (IFFT) to obtain M complex numbers, namely IAk and IBk, and finally, obtaining the joint estimation on time error delta tk, gain error gk, and offset error ok, k=0, 1, L M-1 through phase angle extraction and a modulus operation algorithm module. The method for implementing real-time correction comprises the step of: utilizing a comprehensive correction mechanism formed by a subtractor, a divider and a fractional delay filter to correct the offset error, the gain error and the time error existing in the sampling data of the channels respectively. By the method, joint estimation is performed on the three errors, SFDR of the sampling sequence is improved through the real-time correction, and a filter coefficient is not required to be updated or a correction module is not required to be redesigned even if channel errors are changed, so the aim of the real-time correction is fulfilled.
Owner:UNIV OF ELECTRONICS SCI & TECH OF CHINA

Partial discharge detecting system for all-fiber power transformer and detecting method thereof

The invention relates to a partial discharge detecting system for all-fiber power transformer and a detecting method thereof. The system comprises a controller, a transmission device and a detecting device. The detecting device comprises four groups of fiber bragg grating F-P ultrasonic sensors, optical fiber delayers are arranged between every two fiber bragg gratings, and the four groups of fiber bragg grating F-P ultrasonic sensors and a fluorescent probe are in serial connection on an optical fiber. The transmission device is connected with the detecting device through a through part. The controller is connected with the transmission device. In the calculation processing end, the partial discharge position can be calculated and determined through the time difference for the four groups of sensors to receive sound wave and by taking time division multiplexing time error into consideration. According to the strength of stimulated emission light signals of the fluorescent probe, the apparent discharge magnitude of the partial discharge is calculated. Through the comparison between the ultrasonic sensors and the signals of the fluorescent probe, whether the system is interfered by external environment to cause error judgment is judged. Furthermore, false alarm of the system is avoided. The partial discharge detecting system has the advantages of being simple in structure, facilitating networking, resisting to electromagnetic interference and the like.
Owner:STATE GRID CORP OF CHINA +1

Electric energy metering and monitoring system of intelligent gateway

The invention relates to an electric energy metering and monitoring system of an intelligent gateway, which mainly comprises a three-phase standard ammeter and a built-in computer thereof, a remote switching control device, contactless intelligent open-loop current pincers, a detected meter switching control unit, an error verification unit and the like, wherein the remote switching control device comprises an MPU (Micro Processor Unit) chip control circuit and a relay switching circuit which are arranged in a switching box; 8 paths of input ends for connecting a detected meter are arranged on the switching box; the current signals of the detected meter, which are taken out by the current pincers, and the voltage signals and pulse signals of the detected meter, which are taken out by a voltage and pulse sampling circuit of the detected meter, are accessed to the standard ammeter through the switching box; and the error verification of the detected meter is realized through a software platform. The electric energy metering and monitoring system provided by the invention has the characteristics of simple integral design, real-time error verification and high safety, and is convenient to install.
Owner:STATE GRID SICHUAN ELECTRIC POWER CORP ELECTRIC POWER RES INST

Method and system for transferring protection time in synchronous network

The invention discloses a method and a system for protecting time transfer in synchronization network; a corresponding module is added to the prior art to use time synchronization frequency of the synchronization network as the basis of time synchronization protocol, so the network is ensured to synchronously lock clock signal; a synchronization network clock source which participates in selection is configured, and the clock source selection mode is configured; current clock source is selected according to the selection mode, and the frequency state of the current clock source is synchronously locked; the current clock source state is used as state basis of accurate time protocol port to sequentially lock time of element location nodes in the synchronization network. The corresponding module is added to the prior art to use time synchronization frequency of the synchronization network as the basis of time synchronization protocol, so the time transfer error in element location nodes is greatly reduced, and the time error in large scale networking is reduced, and the stability of synchronization network is improved in the switching process of clock sources.
Owner:ZTE CORP

Integrated navigation system of strapdown inertial navigation system (SINS)/central nervous system (CNS)/global navigation satellite system (GNSS) of geostationary earth orbit (GEO) transfer vehicle

The invention provides an integrated navigation system of a strapdown inertial navigation system (SINS) / a central nervous system (CNS) / a global navigation satellite system (GNSS) of a geostationary earth orbit (GEO) transfer vehicle. The SINS serves as a core of the integrated navigation system. Navigation information of the GEO transfer vehicle is calculated and output by the SINS in real time, fault detection and isolation are conducted to data output by a GNSS receiver, a globe sensor and a star sensor by utilizing a residual error chi 2 detecting method improved by a kalman filter. Information fusion is conducted to output information of the globe sensor and the star sensor in a celestial navigation system, pseudorange measuring information output by the GNSS receiver and the navigation information output by the SINS. Navigation errors, inertial device errors, globe sensor errors and GNSS receiver time errors of the GEO transfer vehicle are evaluated in real time, and the navigation errors of the GEO transfer vehicle are corrected through a manner of closed loop feedback correction in real time so that in-orbit self navigation with high precision and high reliability of the GEO transfer vehicle is achieved, and therefore meaningful effects of good subjectivity, high precision, good robustness and high reliability are obtained.
Owner:SHANGHAI AEROSPACE SYST ENG INST

Cell switching method and device

InactiveCN103220740ALow switching synchronization time errorIncrease success rateSynchronisation arrangementTime errorTelecommunications
The invention discloses a cell switching method and device. The cell switching method and device is used in a satellite communication system and enables switching of a user to be low in synchronization time error and high in success rate. Meanwhile, according to the cell switching method and device, in a switching process, excessive occupancy of resources is avoided, and the using rate of the resources is improved. The cell switching method comprises the following steps: network-side equipment sends a synchronization parameter of a target spot beam to user equipment (UE) to instruct the UE to stay synchronous with the target spot beam, the network-side equipment then acquires position information of the UE and power information of the spot beam, and then the network-side equipment judges whether to carry out cell switching on the UE or not according to the position information of the UE and the power information of the spot beam, wherein the position information of the UE and the power information of the spot beam are reported by the UE.
Owner:CHINA ACAD OF TELECOMM TECH

Turbo decoder

Detection of errors in the results of turbo decoding is performed while decoding is being repeated. If absence of errors is detected, the results of decoding are output, even though repetition of the decoding operation is in progress, and further decoding is discontinued. Further, the number of times errors are detected in decoded results when decoding has been performed a set number of times is monitored and the decoding operation is executed again if the number of times errors are detected is equal to or less than a set value. Further, one of first and second decoded results output from first and second elementary decoders that construct a turbo decoder is selected as appropriate and is then output.
Owner:FUJITSU LTD

Range migration correction method for pulse Doppler (PD) radar in feeble signal detection process

InactiveCN102323575ALow impact on detection performanceEasy to detectWave based measurement systemsTime errorRadar systems
The invention discloses a range migration correction method for a pulse Doppler (PD) radar in a feeble signal detection process, which mainly solves the problems that the discrete time sampling error is not considered, and the detection performance is low in the prior art, and is realized by the steps as follows: transmitting a set of linear frequency-modulation pulse signals of which the bandwidth does not exceed 1 percent of a centre carrier frequency by the radar; carrying out mixing on echo data to obtain a base band radar echo signal; carrying out Fourier transformation on the base band radar echo signal in a fast time domain; carrying out digital pulse compression on a signal obtained by carrying out the Fourier transformation through the fast time domain in the fast time domain, and finding out a corresponding pulse signal when the discrete time error is minimum; by taking the pulse signal as an alignment reference, realizing Keystone transformation by using an SINC interpolation method, and carrying out Doppler fuzzy compensation; and carrying out the Fourier transformation in the fast time domain, and carrying out coherent accumulation to work out a range cell in which the target is located and a Doppler channel. Compared with similar methods, the range migration correction method for PD radar in the feeble signal detection process is capable of reducing the influenceof the discrete time sampling error to minimum, and is capable of improving the detection performance of a radar system.
Owner:XIDIAN UNIV

Method and apparatus for providing wireless communication system synchronization

When insufficient traffic is present in the network to maintain synchronization in this manner, other methods must be used. One approach involves making direct measurements of the timing between base stations. This is accomplished in one of two ways. The base may interrupt its transmissions on all sectors for a short interval during which it determines the time of arrival of signals from other base stations. Given knowledge of the other base station locations, time errors relative to all other base stations may be derived. Alternatively, the base may send a short signal at high power in the mobile transmit band. This time-of-arrival of this signal is measured by the surrounding base stations and the time errors between pairs of base stations are computed. In some cases, a base station may be isolated sufficiently from all other base stations in the network such that direct base-to-base measurement is not viable. In this case, a fixed mobile is placed at a location in the handoff region between the isolated cell and another cell in the network. The fixed mobile either performs measurements of base station pilots on command of the base and reports the timing information, or sends a burst transmission at a specified time and power level to be measured by the base stations.
Owner:QUALCOMM INC

Seismic data analysis using ocean bottom node data collection

The present invention permits RMS traveltime error in a seismic data acquisition to be minimized. Field measurements of source and receiver coordinates, speed of sound in water as a function of depth and time, receiver timing, and clock drift are first collected. The seismic data is then examined to measure travel time from each source to each reciever. A model travel time can then be computed based on the field measurements. By iteratively perturbing at least one of the field measured data using a look-up table and calculating the travel time after each perturbation until an acceptable RMS error has been achieved, conditioned seismic data that takes into account the dynamic nature of the water column will provide the basis for creating an accurate seismic map that is unaffected by the changing water conditions.
Owner:FAIRFIELD INDUSTRIES INC
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