Magellan Systems Japan, Inc.

Other

Advanced Telesensors, Inc.

United States of America As Represented by the Secretary of the Air Force

Invisitrack, Inc.

Zonaar Corporation

Comm Sciences Corporation

Lawrence Randolph Weill

Benjamin D Fisher

Ronald C Gamble

Steve Perry Monacos

Felix Markhovsky

Truman Prevatt

Gary Edwin Sutton

Jon L Vavrus

James R Gaskill, Jr

Andrey Yushkov

Stig M Pedersen

Vladimir Zhulanov

A method for remotely sensing cardiac-related data of an animal subject includes transmitting a RF signal to impinge on tissue of the subject, receiving a reflected portion of the RF signal, generating baseband data, filtering baseband data (e.g., including high pass filtering), performing waveform phase position determination, performing at least one auto-correlation of the waveform phase position determined data, determining periodicity of the auto-correlated data, and (i) computing heart rate using a maximum periodicity of the periodicity, or (ii) identifying abnormalities in cardiac function, such as may be indicated by temporal variations in heart rate and/or signal amplitude corresponding to cardiac activity. Multiple bandpass filtering schemes may be employed.

System and method for facilitating reflectometric detection of physiologic activity

A system for monitoring and directing athletic or other physical activities is disclosed. In one embodiment of the invention, a headset worn by an athlete includes one or more sensors, a microprocessor, a non-volatile memory and a communication link. The athlete's headset receives and transmits signals to a coach while the athlete is performing an activity. In this embodiment, the present invention provides coordinated audio streams to the athlete during his/her activity and training.

Activity monitoring and directing system

Sub-microsecond time transfer in a GPS/GNSS receiver using a weak GPS/GNSS signal is provided. The digitized complex baseband signal and the generated PN code are cross-correlated for each code period so as to output a complex correlation value at each code epoch of the generated PN code, where a sequence of the output correlation values form a data stream representing the navigation message. Bit synchronization generates bit sync pulses at bit boundaries. The location of a target segment having a known sequence at a known bit location in the navigation message is detected by searching through a plurality of subframes and accumulating search results for the plurality of subframes. Transmission time of the target segment is determined from the detected location of the target segment, with a certain time ambiguity. Accurate local time is determined by solving the time ambiguity using approximate time obtained from an external source.

Process for sub-microsecond time transfer using weak GPS/GNSS signals

A method and apparatus provide high-sensitivity GPS/GNSS signal acquisition in a stationary GPS/GNSS receiver. The uncertainty in frequency due to apparent Doppler shift is partitioned into a plurality of contiguous frequency bins, and the uncertainty in location of navigation data bit boundaries is partitioned into equally spaced trial bit boundary locations. For each combination of the trial bit boundary location and the frequency bin, a signal block of captured complex baseband signal is Doppler-compensated using a phase rotator, and then synchronously summed with a periodicity of one period of C/A code so as to produce a compressed sample block having N samples. Each compressed sample block is cross-correlated with one period of reference C/A code to produce an N-value correlation function. A predetermined number of magnitudes of the N-value correlation functions are stack-accumulated into an array with precession compensation so as to find a correlation peak having the largest value.

Method and apparatus for acquisition, tracking, and sub-microsecond time transfer using weak GPS/GNSS signals

A low-cost GPS/GNSS receiver receives a satellite signal at an RF frequency (fRF). The GPS/GNSS receiver includes a front end section for receiving the satellite signal and generating a digital complex signal having a first bandwidth, the received satellite signal being converted into a complex signal before digitizing, a signal capturing section for searching for and acquiring the satellite signal, the signal capturing section including a capture memory, a baseband processor for tracking the acquired satellite signal, and a signal splitter coupled to the front end section. The signal splitter splits the digital complex signal into two bandwidths, by generating a narrowband digital complex signal having a second bandwidth substantially smaller than the first bandwidth. The signal splitter provides the narrowband digital signal to the capture memory and the wider first bandwidth digital complex signal to the baseband processor.

Low cost, high performance GPS/GNSS receiver architecture

Sub-microsecond time transfer in a GPS/GNSS receiver using a weak GPS/GNSS signal is provided. The digitized complex baseband signal and the generated PN code are cross-correlated for each code period so as to output a complex correlation value at each code epoch of the generated PN code, where a sequence of the output correlation values form a data stream representing the navigation message. Bit synchronization generates bit sync pulses at bit boundaries. The location of a target segment having a known sequence at a known bit location in the navigation message is detected by searching through a plurality of sub-frames and accumulating search results for the plurality of subframes. Transmission time of the target segment is determined from the detected location of the target segment, with a certain time ambiguity. Accurate local time is determined by solving the time ambiguity using approximate time obtained from an external source.

Method and apparatus for acquisition, tracking, and transfer using sub-microsecond time transfer using weak GPS/GNSS signals

A method and system for a long range Radio Frequency (RF)-based identification, tracking and locating of objects. The method and system use a narrow bandwidth ranging signal(s), including VHF of lower frequency bands, which minimizes propagation loss and loss of accuracy of the RF locating signals. The method and system includes narrow bandwidth ranging signal multi-path mitigations processor, which further improves the track-locate accuracy. The signal is sent from a Master Unit(s) to a Tag. The signal traveling time is recorded and the distance between the Master(s) and the Tag is calculated. The method and system allow achieving a longer distance of the RF narrow bandwidth ranging signal penetration and an increased accuracy by using VHF bands in conjunction with the narrow bandwidth ranging signal multi-path mitigations processor. The techniques of Digital Signal Processing and Software-Defined Radio are used. The actual waveforms transmitted and received by the radios are defined by the software. The roles of the Master Unit(s) and the Tag can be reversed.

Methods and system for multi-path mitigation in tracking objects using reduced attenuation RF technology

In ranging systems such as GPS, radar, and the like, accuracy of the ranging information recovered depends on the phase linearity of the ranging receiver, generally implemented as a superheterodyne radio. Superheterodyne radios use bandpass filters in their Intermediate Frequency (IF) amplifiers to accomplish suppression of adjacent channel signal interference. Depending on the ratio of IF center-frequency to signal-bandwidth, such filters evidence phase non-linearity affecting the signal group delay response. This generally manifests in coupling of the in-phase and quadrature detected signals during signal modulation changes in state. If this effect is ignored, reduced accuracy in the recovery of ranging information can be expected. One solution is to incorporate in the ranging receiver a phase non-linearity compensation structure, but this has an adverse economic impact. On study, it has been determined that real-time Maximum Likelihood estimates of signal parameters in a multipath environment is both tractable and efficacious. The subject of this invention is means to obtain Maximum Likelihood estimates of the amplitude, carrier phase, and delay parameters of the direct and secondary path signals arising in a multipath environment when the receiver signal modulation is complex-valued, an appropriate signal model when phase non-linearity is operating. An algorithmic solution to the problem of ranging receiver induced phase non-linearity is a preferred solution, since there is little to no economic impact.

Complex maximum likelihood range estimator in a multipath environment

A process is disclosed for discriminating between received ranging signals, such as GPS, GNSS, and radar signals, which arrive via a single path and those which arrive via multiple paths. The number of paths is also estimated. This is accomplished by comparing the residual for an iorder ML estimator of signal time of arrival, where order refers to the number of signal paths for which the estimator is optimal, to a discriminant determined either analytically or empirically and deciding that i distinct signal path components are present in the observation of the signal if for all korder estimators where k&#x3c;i, the residual is greater than the discriminant for that order estimator and the residual of the iorder estimator is not greater than the discriminant for that order estimator. The invention is particularly useful in obtaining an appropriate signal model for model-based estimation methods.

Method for improving multipath mitigator low path separation error behavior

A method of forming a cross-correlation function mathematically as an inner product of the samples of a received signal r(t) and a replica of the signal modulation function m(t), with a computational burden reduced by many orders of magnitude in pseudonoise (PN) coded ranging applications is accomplished by a two step process. First, a single weighted sum of the signal samples forms a small dimension vector, of the order of tens of elements. Second, the inner product of this vector and vectors of the same dimension of samples of the signal modulation generating function, delayed by arbitrarily many values of the delay parameter &#x3c4;, result in fine delay resolution correlation function values. The process comparatively entails a relatively small computational burden, does not compromise fidelity, and makes real-time optimal range estimation practical.

Binary-valued signal modulation compression for high speed cross-correlation

A base station (server) transmits assisting information to the user's receiver (rover). Signals from at least 5 satellites are used for 3-dimensional positioning. Pseudorange measurements are made in a system of equations having a minimum set of unknowns X,Y,Z, and T. (X,Y,Z) is the 3D rover position in a predefined coordinate system, and T is the time at which simultaneous measurements are made to determine pseudoranges to all satellites. The position of each satellite is a vector-valued function &#x192;(T) of said time T, where fis determined from satellite ephemeris data or its equivalent, sent to the rover over a communication link, as well as from knowledge of the approximate position of the rover.

Process for accurate location determination in GPS positioning system

A method for mitigating multipath effects in radio systems which is based on searching for and finding a maximum likelihood estimate of range for a received signal is provided. In determining the maximum likelihood estimate, the correlation process uses a high resolution step method in processing the received signal sample values to develop an estimation statistic. The estimation statistic using the correlations of the received signal is based on a new derived representative set of coefficients formed from a nonlinear combination of parameters of the received signal transformed into a linearly solvable invertible parameter set allowing solution of the maximization process of the estimation statistic over a reduced dimension search space. Additionally there is a method of constraining the relative amplitude of received secondary signals to obtain a refinement of the optimal solution of range. The method includes a process to reduce the magnitude of the processing required by the receiver by reducing the size of the overall sample of the signal that must be managed by the receiver. The method may be used in a signal environment where multiple secondary path signals are received by the signal ranging system.

Method for mitigating multipath effects in radio systems

The location of a mobile unit is determined by evaluating the instantaneous distances between an apparatus traveling above the surface of the earth and the mobile unit. The instantaneous distances are determined by measuring the travel time of a plurality of signals and calculating the distance based on the speed of the signal. One of two possible location regions is identified as the region including the location of the mobile unit by observing the motion of the mobile unit resulting from the rotation of the Earth.

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Seal Beach, CA, United States of America

Lawrence Randolph Weill