180 results about "Doppler measurements" patented technology

Position determination accuracy of a wireless communication device may be negatively affected by a large unaccounted GPS doppler bias, which in turn may affect GPS doppler estimations and GPS doppler measurements conducted by the wireless communication device. The quality of GPS doppler measurements is very important for position location, because poor quality GPS doppler measurements may prevent the wireless communication device from acquiring satellites in the most sensitive modes with narrow frequency ranges, which results in reduced GPS pseudorange measurement yield. Large unaccounted GPS doppler bias also adversely affects position accuracy because of the adverse effect on the GPS code phase measurements time propagation to common time prior to their use in position location calculation. The same is true in the case of unaccounted CDMA code doppler, through the adverse effect on the AFLT code phase measurements time propagation to common time prior to their use in a position location engine. This effect is the biggest concern in the case of large search windows. Therefore, the present disclosure provides a method of optimizing GPS based position location in the presence of time-varying frequency error, including the steps of continuously measuring and / or calculating resulting GPS doppler bias and CDMA code doppler bias and then minimizing their adverse effects with regard to position location determination by re-centering GPS doppler search windows based on the GPS doppler bias value, as well as using GPS doppler bias and CDMA code doppler bias value to properly propagate GPS pseudorange and AFLT pilot phase measurements, respectively, to common time prior to their use in a position location engine.

Method and apparatus for computing position using instantaneous Doppler measurements from satellites is described. In one example, instantaneous Doppler measurements are measured for a plurality of satellite signals relative to a satellite signal receiver. The instantaneous Doppler measurements are transmitted to a server. Position of the satellite signal receiver is computed at the server using the instantaneous Doppler measurements. In another example, at least one fractional pseudorange is measured between the satellite signal receiver and a respective at least one satellite. At least one instantaneous Doppler measurement is measured for a respective at least one satellite signal relative to the satellite signal receiver. The at least one pseudorange and the at least one instantaneous Doppler measurement are sent to a server. Position of the satellite signal receiver is computed at the server using the at least one pseudorange and the at least one instantaneous Doppler measurement.

A measurement system and method for permitting multiple independent measurements of several physical parameters of multiphase fluids flowing through pipes are described. Multiple acoustic transducers are placed in acoustic communication with or attached to the outside surface of a section of existing spool (metal pipe), typically less than 3 feet in length, for noninvasive measurements. Sound speed, sound attenuation, fluid density, fluid flow, container wall resonance characteristics, and Doppler measurements for gas volume fraction may be measured simultaneously by the system. Temperature measurements are made using a temperature sensor for oil-cut correction.

A method of detecting and tracking objects using multiple radar sensors. Objects relative to a host vehicle are detected from radar data generated by a sensing device. The radar data includes Doppler measurement data. Clusters are formed, by a processor, as a function of the radar data. Each cluster represents a respective object. Each respective object is classified, by the processor, as stationary or non-stationary based on the Doppler measurement data of each object and a vehicle speed of the host vehicle. Target tracking is applied, by the processor, on an object using Doppler measurement data over time in response to the object classified as a non-stationary object; otherwise, updating an occupancy grid in response to classifying the object as a stationary object.

Systems, methods and computer-readable media are provided for tracking a moving sports object. In one example, a method of tracking a moving sports object includes calibrating a perspective of an image of a camera to a perspective of a Doppler radar for simultaneous tracking of the moving sports object, and tracking the moving sports object simultaneously with the camera and Doppler radar. The method may further comprise removing offsets or minimizing differences between simultaneous camera measurements and Doppler radar measurements of the moving sports object. The method may also include combining a camera measurement of an angular position of the moving sports object with a simultaneous Doppler measurement of a radial distance, speed or other measurement of the moving sports object.

A method of detecting and tracking objects using multiple radar sensors. Objects relative to a host vehicle are detected from radar data generated by a sensing device. The radar data includes Doppler measurement data. Clusters are formed, by a processor, as a function of the radar data. Each cluster represents a respective object. Each respective object is classified, by the processor, as stationary or non-stationary based on the Doppler measurement data of each object and a vehicle speed of the host vehicle. Target tracking is applied, by the processor, on an object using Doppler measurement data over time in response to the object classified as a non-stationary object; otherwise, updating an occupancy grid in response to classifying the object as a stationary object.

A method is implemented by computer for the management of a convoy comprising at least two vehicles, each of the at least two vehicles comprising satellite positioning means and vehicle-to-vehicle communication means, the method comprising the determination of the relative positioning of the vehicles, the determination comprising the measurement of the propagation time of a signal between vehicles by the communication means, the clocks associated with the communication means being synchronized via satellite positioning means at a reference clock time. Developments comprise the communication between the vehicles of various data (e.g. measurement uncertainties, signal-to-noise ratios, residual values), the determination of absolute locations, the use of an SBAS-type system, the use of differential GPS, the use of Doppler measurements for the turns or even the exclusion of a failing satellite. A computer program product and associated systems are described.

Vector Doppler Imaging (VDI) improves on conventional Color Doppler Imaging (CDI) by giving speed and direction of blood flow at each pixel of a display generated by a computing system. Multiple angles of Plane wave transmissions (PWT) via an ultrasound transducer conveniently give projected Doppler measurements over a wide field of view, providing enough angular diversity to identify velocity vectors in a short time window while capturing transitory flow dynamics. A fast, aliasing-resistant velocity vector estimator for PWT is presented, and VDI imaging of a carotid artery with a 5 MHz linear array is shown using a novel synthetic particle flow visualization method.

A system uses range and Doppler velocity measurements from a lidar system and images from a video system to estimate a six degree-of-freedom trajectory of a target. The system estimates this trajectory in two stages: a first stage in which the range and Doppler measurements from the lidar system along with various feature measurements obtained from the images from the video system are used to estimate first stage motion aspects of the target (i.e., the trajectory of the target); and a second stage in which the images from the video system and the first stage motion aspects of the target are used to estimate second stage motion aspects of the target. Once the second stage motion aspects of the target are estimated, a three-dimensional image of the target may be generated.

A method and apparatus for locating position of a satellite signal receiver is described. In one example, a Doppler offset for each of a plurality of satellite signals relative to the satellite signal receiver is determined at a first time. A position of the satellite signal receiver is then computed using the Doppler offset for each of the plurality of satellite signals. In another example, at least one pseudorange between the satellite signal receiver and a respective at least one satellite is determined. At least one Doppler offset for a respective at least one satellite signal relative to the satellite signal receiver is also determined. A position of the satellite signal receiver is computed using the at least one pseudorange and the at least one Doppler offset.

An ultrasound method and medical devices using same provide for various techniques of sampling blood flow velocity, e.g., at several sampling rates. To minimize the energy required for ultrasound monitoring, pulsed Doppler signal packages provided by a pulsed ultrasound circuit are switched in such a way that the repetition rate is the lowest possible and yet sufficiently high to be able to record the blood flow velocity within the heart. For example, an ultrasound circuit may be activated only within a part of the cardiac cycle designated as the Doppler Measurement Interval (DMI); the ultrasound circuit may be switched between an on state and an off state during the DMI; and / or the ultrasound circuit may also be switched on and off in different sampling modes: detection mode and measurement mode (e.g., using different sampling rates).

A method and apparatus for channel estimation in a rake receiver of a CDMA communication system operates with a finite-impulse-response channel estimation filter with L taps and having a fixed delay. A pilot sequence of a received sequence of data from a channel of the communication system on the rake receiver is input. A quality of the channel of the communication system is determined using noise or Doppler measurements. These measurements are used in adjusting a bandwidth of the filter to accommodate the channel quality while keeping the fixed delay, which minimizes the delay buffer size. The filter is then used to operate on the received sequence of data to provide coherent modulation.

The invention discloses a target tracking method based on measurement conversion Kalman filtering state fusion, which belongs to the field of radar target tracking, and particularly relates to a statistical property calculation method utilizing Doppler radar measurement conversion errors. The state fusion target tracking method comprises the steps of: calculating statistical properties of converted measurement errors based on a predicted value measurement conversion method, regarding a position predicted value in a rectangular coordinate system as a condition to obtain a mean value and a covariance of the converted measurement errors, and eliminating correlation between the covariance of the converted measurement errors and measurement errors; and then performing state estimation on a position and Doppler measurement, and finally using a least mean square error criterion to fuse estimation results of the position and Doppler measurement, so as to obtain a final state estimation. The tracking method can be further extended to CV and CA motion models of a 3D radar.

A fluid flow measurement instrument is provided. The measurement instrument includes a sensor producing a time domain signal representative of reflections of an emitted signal; and a meter being coupled to the sensor and configured to: receive the time domain signal; create two or more spectral estimates for the time domain signal, wherein said two or more spectral estimates have different frequency ranges and resolutions; determine a frequency offset value using one or more of the two or more spectral estimates; and convert the frequency offset value into a fluid velocity. Other aspects are described and claimed.

A method and apparatus for channel estimation in a rake receiver of a CDMA communication system operates with a finite-impulse-response channel estimation s filter with L taps and having a fixed delay. A pilot sequence of a received sequence of data from a channel of the communication system on the rake receiver is input. A quality of the channel of the communication system is determined using noise or Doppler measurements. These measurements are used in adjusting a bandwidth of the filter to accommodate the channel quality while keeping the fixed delay, which minimizes the delay buffer size. The filter is then used to operate on the received sequence of data to provide coherent modulation.

The invention relates to a symbol synchronization and Doppler compensation method for a mobile orthogonal frequency division multiplexing (OFDM) underwater sound communication signal. The method comprises the following steps of: obtaining rough estimation of a first OFMD symbol start position according to a frame header signal, extracting a symbol, then obtaining Doppler expansion rough estimation of the symbol according to a frequency measurement simple-frequency signal in the symbol, converting the symbol to a frequency domain according to Chirp-z conversion, searching a precise start moment and a Doppler expansion amount of the symbol by taking a pilot of the frequency domain and a relevant value of a local pilot as cost functions, presuming the start position of the next symbol according to the start position of the current symbol, extracting the next symbol, and repeating the operations till the end of a frame of signal. According to the Doppler measurement and compensation method, based on the Chirp-z conversion, the measurement and compensation precision is high; the Chirp-z conversion is implemented according to fast Fourier transformation (FFT); the practicability is high; according to the Doppler expansion search method which is in a manner that large step length is superior to small step length, so that the search efficiency is high; a Doppler measurement range is not limited; and the method can be used for constant-speed motion and variable-speed motion.

An ultrasound method and medical devices using same provide for various techniques of sampling blood flow velocity, e.g., at several sampling rates. To minimize the energy required for ultrasound monitoring, pulsed Doppler signal packages provided by a pulsed ultrasound circuit are switched in such a way that the repetition rate is the lowest possible and yet sufficiently high to be able to record the blood flow velocity within the heart. For example, an ultrasound circuit may be activated only within a part of the cardiac cycle designated as the Doppler Measurement Interval (DMI); the ultrasound circuit may be switched between an on state and an off state during the DMI; and / or the ultrasound circuit may also be switched on and off in different sampling modes: detection mode and measurement mode (e.g., using different sampling rates).

The invention discloses a satellite navigation positioning resolving method based on Doppler smoothing pseudorange under a high-sensitivity environment. In the invention, a pseudorange measuring value is smoothened through a Doppler measuring value reproduced by a receiver, the problem of serious distortion of a carrier phase during the smoothing pseudorange of the carrier phase under a condition of weak signals is solved. The method comprises the following steps of: correcting the pseudorange at every new epoch moment according to Doppler frequency offset reproduced by the receiver from the moment to the initial moment to acquire an initial moment pseudorange corrected value; averaging the initial moment pseudorange corrected value to obtain the initial moment pseudorange corrected average value when the quantity of the initial moment pseudorange corrected value reaches to the requirement of window width; and finally carrying out Doppler frequency offset correction from any moment to the initial moment based on the initial moment pseudorange corrected value to finally acquire high-accuracy pseudorange at any moment. The invention is suitable for various satellite navigation positioning resolving systems, such as a GPS (Global Position System), a GLONASS (Global Navigation Satellite System) and the like.

A flow meter and method for measuring flow in liquids which may have entrained bubbles or foreign matter. The meter performs alternate transit time and Doppler measurements. The transit time measurements are used to calculate flow so long as they are successful. If the transit time measurements are not successful, the Doppler measurements are used.

The invention discloses a position and speed combined estimation method for satellite navigation, which solves the problem of real-time estimation of the position and speed of a receiver when an accurate carrier phase measured value cannot be acquired by modeling a recurrent Doppler measured value of the receiver and performing coupled solution with a pseudo-range measurement model based on the correlation between the Doppler measured value and the position of the receiver. The method comprises the following steps of: performing combined estimation on positioning and speed measurement at each new epoch moment according to the current pseudo-range measured value and Doppler measured value; and weighting least square based on a nonlinear equation system to solve an estimated position in an iterative process to replace a pseudo-range positioning result to serve as a reference position for the speed estimation of the receiver, so that the speed estimated value is gradually converged along with the position estimation. Meanwhile, estimation error comprises speed error to ensure that the algorithm convergence judgment is stricter, and the search step of an algorithm around the actual position is reduced so as to acquire higher estimation accuracy. By the method, real-time positioning and speed measurement can be reliably realized, and the method is suitable for various satellite navigation systems such as a global positioning system (GPS), a global orbit navigation satellite system (GLONASS) and the like.

The invention discloses a doppler differential velocity model and a method for combined navigation by using a doppler differential velocity model and an X-ray pulsar. The doppler differential velocity model is Y<s>(t)=h<s>(X, t)+omegav, wherein omegav is doppler measurement noise; Y<s> and h<s> respectively represent a measurement value and a measurement equation; Y<s>=vD2-vD1; the equation is as shown in the specification. The method for combined navigation by using the doppler differential velocity model and the X-ray pulsar comprises the following steps: 1, building an orbital dynamics model of a deep space probe; 2, building an X-ray pulsar navigation ranging model; 3, building the doppler differential velocity model; 4, filtering by using an extended kalman filter. Compared with the prior art, the doppler differential velocity model has the advantages that (1) compared with the existing pulsar / doppler combined navigation methods, the doppler differential velocity model still can normally and stably work under an unstable solar spectrum; (2) compared with the pulsar navigation method and the doppler navigation method, a plurality of navigation messages are fully utilized by the method, the method has complete observability, and the locating information with higher precision can be provided.

A measurement system and method for permitting multiple independent measurements of several physical parameters of multiphase fluids flowing through pipes are described. Multiple acoustic transducers are placed in acoustic communication with or attached to the outside surface of a section of existing spool (metal pipe), typically less than 3 feet in length, for noninvasive measurements. Sound speed, sound attenuation, fluid density, fluid flow, container wall resonance characteristics, and Doppler measurements for gas volume fraction may be measured simultaneously by the system. Temperature measurements are made using a temperature sensor for oil-cut correction.

A method of detecting and tracking objects using multiple radar sensors. Objects relative to a host vehicle are detected from radar data generated by a sensing device. The radar data includes Doppler measurement data. Clusters are formed, by a processor, as a function of the radar data. Each cluster represents a respective object. Each respective object is classified, by the processor, as stationary or non-stationary based on the Doppler measurement data of each object and a vehicle speed of the host vehicle. Target tracking is applied, by the processor, on an object using Doppler measurement data over time in response to the object classified as a non-stationary object; otherwise, updating an occupancy grid in response to classifying the object as a stationary object.

The invention relates to the field of acoustic and signal processing, and mainly discloses a Doppler measurement and correction method for MFSK underwater acoustic communication. At a transmitting end, a frequency point falls on a sideband of an encoded signal by mapping two Doppler measurement spectrum lines; a receiving end can obtain a Doppler measurement value with higher resolution by performing Zoom-FFT processing on a compound fundamental frequency signal of the encoded signal; and finally the measurement value is used for performing Doppler correction and the compensation of time synchronization on the compound fundamental frequency signal. A DSP realizes the setting of two-stage ping-pong buffers which store a radiofrequency signal acquired by an AD and a compound fundamental frequency signal of a digital down converter respectively, improve the real-time and reduce the storage capacity. The method has the advantages that: the method overcomes the disadvantages of measuring Doppler by a single-frequency signal in the prior art; the measurement value can be reflected as a true value for each encoded signal; the measurement spectrum lines can be mapped at a frequency band of response difference and do not occupy an actual communication frequency band; and Zoom-FFT technology can improve the resolution of Doppler measurement, has small operation amount, also occupies less storage resources, and is easy to realize the engineering.

The invention discloses a predicted value based measurement conversion and sequential filtering maneuvering target tracking method, relates to the field of radar target tracking, and mainly aims at the field of Doppler radar tracking under maneuvering target tracking. A predicted value based sequential filtering method is combined under the framework of an interactive multi-model algorithm to realize target tracking. The model probability is decided by both a position model probability and a Doppler model probability, and the model probability is estimated more accurately; and measurement conversion based on the predicted value can be used to eliminate the correlation between an error statistical characteristic and a measuring value of the measurement conversion error. The method can be used for maneuvering target tracking of Doppler measurement effectively at the same time.

The invention provides a two-phase flow phase-splitting flow velocity acoustic-electric bimodal measuring method. A used bimodal sensor comprises an electric sensor and an ultrasonic Doppler probe. The measuring method comprises: acquiring a signal and acquiring water phase volume fraction, oil phase volume fraction, and two-phase flow mixed density by using the electric sensor; determining the measuring space of the ultrasonic Doppler probe and computing the equivalent height of the measuring space; computing a difference between ultrasonic signal frequency acquired by a ultrasonic receiving probe and exciting ultrasonic signal frequency emitted from a ultrasonic emitting probe and computing average flow velocity in the measuring space; establishing a fluid flow velocity distribution relation of a position in a pipeline and a certain distance to the wall of the pipeline; establishing a relation between Doppler measurement flow velocity and boundary layer flow velocity in the measuring space; solving the boundary layer flow velocity; and computing total flow velocity and acquiring the water phase flow velocity and oil phase flow velocity. The two-phase flow phase-splitting flow velocity acoustic-electric bimodal measuring method may accurately acquire two-phase flow phase volume fraction by a noninvasive mode.

The invention discloses a vehicular fatigue driving monitoring system; a Doppler radar detection unit for detecting physiological signal changes of a driver is mounted in a cab and comprises a Doppler radar sensor, a power module, a signal preprocessing module, a differential amplifier, an active bandpass filter, a respiratory and heartbeat signal separation module and a MCU (microcontroller unit) module, wherein the Doppler radar sensor is used for transmitting continuous wave radar signals to a human chest and outputting low-frequency signals, the low-frequency signals are sequentially subjected to multistage signal treatment, and the MCU module acquires human a body respiratory signal and a heartbeat signal and judges whether the driver is in fatigue driving state or not according to the changes in the body respiratory signal and heartbeat signal. Compared with the prior art, it is proposed for the first time that fatigue level of a driver is monitored by means of Doppler measurement technology, detection of steering wheel angle information is added to the system, and fatigue driving measurement precision is improved through multi-source information processing.

Systems, devices, and methods for synthetic aperture acoustic imaging, range-Doppler measurements, and therapies are disclosed. One synthetic aperture acoustic system includes a waveform generation and processing device and an acoustic probe device that are designed to enable generation, transmission, reception, and processing of coherent, spread-spectrum, instantaneous-wideband, coded waveforms in synthetic aperture ultrasound (SAU) applications.