Patent application number | Description | Published |
20080297407 | GNSS RECEIVER AND ANTENNA SYSTEM INCLUDING A DIGITAL COMMUNICATION SUBSYSTEM - A GNSS receiver and antenna system transmits signals from an antenna structure to a remote GNSS receiver and includes a digital communications subsystem that utilizes a high speed digital communications conductor. The transmissions are digital signals that preserve GNSS satellite signal frequency and/or carrier and code phase information. The system may transmit digital signals corresponding to GNSS signals such as GPS, GLONAS, Galileo and Compass satellite signals. In addition, the system may transmit, over the same digital communications conductor in appropriately formatted digital signals, ranging signals from ground-based transmitters or other satellites, differential GNSS correction signals from beacons or base GPS receivers, and/or signals from transmitting or co-located sensors, such as inertial sensors, temperature sensors and so forth. The digital signals include in headers or payload relative timing and carrier and code phase information and, as appropriate, information that identifies the signals by source or type, such as information that identifies the frequencies or the antennas or antenna elements providing the respective signals. | 12-04-2008 |
20090012712 | Assisted Seismic Measuring System Including GPS Receivers - A system for analyzing three-dimensional seismic data includes a plurality of digitizer units, each with a configuration of geophones, a data recording and control center, a base GPS receiver with an associated antenna with a substantially unrestricted view of the sky and at the respective digitizer units low-power slave GPS receivers that acquire and track GPS satellite signals using tracking assistance information provided by the base GPS receiver. The slave GPS receivers use the tracking assistance information to acquire and track GPS satellite signals that may be relatively weak at the receivers, due to conditions at the site, such as foliage canopies and so forth. The system processes range information provided by the slave GPS receivers over an extended period of time. In this way, the precise positions of the respective slave GPS receivers, and thus, the digitizer units, can be calculated, even if the slave GPS receivers are able to observe and collect data from sets of two or more satellites for only three or four relatively short time intervals at various sky positions during the extended period. The slave GPS receivers then locally produce for the digitizer units timing signals that are based on the GPS codes and synchronized across the system. If a given slave GPS receiver cannot, at a given time, track any GPS satellite signals, a nearby slave GPS receiver supplies the timing information required for the geophone data gathering operations. | 01-08-2009 |
20090117928 | SYSTEM AND METHOD FOR DISTRIBUTING TIME AND FREQUENCY OVER A NETWORK - A system to distribute accurate time and/or frequency over a network utilizing signals of opportunity transmitted by one or more local transmitters with known locations, the system includes a base receiver with a clock synchronized to a reference time scale such as GNSS or UTC time that saves a series of samples of the signals of opportunity and time tags the series with a calculated time of broadcast. A remote receiver saves samples of the signals of opportunity and correlates the series with the saved samples. The remote receiver calculates a time of transmission of saved samples that correspond to the series, determines a time offset as a difference in the time of broadcast calculated at the remote receiver and the time of broadcast calculated at the base receiver, and determines the time offset with respect to the base receiver. The base receiver further or instead phase locks to the signal opportunity and at predetermined intervals determines phase measurements of the integrated carrier frequency of the signal of opportunity and provides the phase information to the remote receiver. The remote receiver, which is also phase locked to the same signal of opportunity, uses the phase measurement information to frequency lock its clock to the base receiver clock by determining a frequency error based on the rate of change of phase measurements made at the base receiver and the remote receiver. | 05-07-2009 |
20090121940 | SYSTEM FOR DETERMINING POSITION OVER A NETWORK - A system to determine position, frequency and clock offsets over a network utilizing signals of opportunity transmitted by one or more transmitters with known locations, the system includes a base receiver with a clock and a known position that determines ranges to the transmitters, takes a series of samples of the signals of opportunity and time tags the series with times of receipt, calculated times of transmission based on the calculated ranges, or both. The base receiver transmits the time tagged series and, as appropriate, computed ranges to the remote receivers. A given remote receiver saves and time tags samples of the signals of opportunity, correlates the time-tagged series with the saved samples, and calculates a time offset as a time difference of the times of receipt at the remote receiver and either the time of receipt at the base receiver or the time of transmission calculated at the base receiver. The remote receiver calculates position based on the time offsets, and as appropriate, the ranges provided by the base receiver. The elevations of the remote receivers may be calculated as part of the position calculations, determined iteratively based on constraining the Z coordinate to an average elevation, or determined from differences in air pressure sensor readings at the base and remoter receivers. | 05-14-2009 |
20090175319 | APPARATUS FOR AND METHOD OF MAKING PULSE-SHAPE MEASUREMENTS - A receiver includes a pre-correlation filter that forms an image of the average chip shape of a received signal over a specified period of time. The filter includes an array of complex accumulation registers that accumulate measurements that are associated with signal samples from specific ranges of locations, or code chip phase angles, along a spread-spectrum chip. Using the accumulated measurements, the receiver estimates the location of the chip transitions in a direct path signal component. The receiver may thereafter change the starting point, size and number of ranges, such that the accumulation registers accumulate more detail from the chip edges. The receiver in addition may compare the accumulated measurements with a reference pulse shape to determine if any interference is present in the received transmission that will distort ranging information calculated from the received signal. | 07-09-2009 |
20090322601 | GNSS RECEIVER USING SIGNALS OF OPPORTUNITY AND ASSISTANCE INFORMATION TO REDUCE THE TIME TO FIRST FIX - A GNSS receiver reduces the time to first fix by utilizing the properties of existing radiated signals of opportunity, such as AM or FM radio signals, television signals and so forth, to reduce the uncertainties associated with oscillator frequency and phase , and further utilizing an Almanac and battery backed-up date and time to determine the satellites in view and reduce the uncertainties associated with Doppler. The receiver may use multiple signals of opportunity to determine the city or local area in which the receiver is located based on the set of frequencies of the signals, and also to reduce search uncertainties for oscillator frequency by estimating an offset based on the differences between the frequencies of the respective signals of opportunity at the receiver and the nominal broadcast frequencies of the signals. | 12-31-2009 |
20100103030 | SEISMIC MEASUREMENT SYSTEM INCLUDING GPS RECEIVERS - A system for determining positions of fixed-position satellite signal receivers that have restricted views of the sky includes a data recording control center, and one or more base satellite signal receivers with associated antennas that together have substantially unrestricted views of the sky. The system batch processes range information provided by the fixed-position receivers over an extended period of time, determining the three dimensional position of a given fixed-position receiver using range data from at least three relatively short time intervals associated with different sky positions in which the receiver is tracking any two or more satellite signals simultaneously. | 04-29-2010 |
20100149032 | SYSTEM FOR DETERMINING POSITION USING TWO WAY TIME TRANSFER SIGNALS - A system for enhancing location estimates by movable rovers including one or more base stations that engage in two way time transfer (TWTT) with the rovers. Each TWTT operation between a given base station and a given rover provides range measurements and clock differences between the base station and rover. The range measurements are based on the travel time of return TWTT signals and the clock differences are based on a phase offset of a code in the return TWTT signal and/or timing information included in the return TWTT signals. | 06-17-2010 |
20100246645 | APPARATUS FOR AND METHOD OF MAKING PULSE-SHAPE MEASUREMENTS - A receiver includes a pre-correlation filter that forms an image of the average chip shape of a received signal over a specified period of time. The filter includes an array of complex accumulation registers that accumulate measurements that are associated with signal samples from specific ranges of locations, or code chip phase angles, along a spread-spectrum chip. Using the accumulated measurements, the receiver estimates the location of the chip transitions in a direct path signal component. The receiver may thereafter change the starting points, sizes and numbers of ranges, such that the accumulation registers accumulate more detail from the chip edges. The receiver in addition may use the accumulated measurements from selected registers and/or selected groups of registers, to produce the correlation values that are needed to perform one or more correlation techniques and/or one or more multipath mitigation techniques. As appropriate, the sizes and/or starting points of the bins, and/or the selections of the bins for the various groupings may be altered, to change the spacings, locations, and so forth to which correlation values correspond. | 09-30-2010 |
20110090113 | SHORT AND ULTRA-SHORT BASELINE PHASE MAPS - A system for generating and utilizing a look-up mechanism consisting of one or more phase difference error maps, tables and/or mathematical models calculates the respective maps, tables and/or models by placing a short baseline or ultra-short baseline antenna array in a known location and known orientation, determining angles of incidence of incoming GNSS satellite signals with respect the antenna array and calculating expected carrier phase differences between respective pairs of antennas, calculating measured carrier phase differences between the respective pairs of antennas, and determining carrier phase difference errors using the expected and measured carrier phase differences. The carrier phase difference errors are then recorded in the look-up mechanism, with the maps and, as appropriate, look-up tables for the respective pairs of antennas being indexed by angles of incidence. Thereafter, the system utilizes the look-up mechanism when determining the unknown orientation of the antenna structure. For respective pairs of antennas, the system enters the look-up mechanism based on angles of incidence determined from a calculated orientation, and uses the retrieved values in the calculation of a corrected orientation, to compensate for phase distortion. | 04-21-2011 |
20110090114 | ULTRA SHORT BASELINE GNSS RECEIVER - A GNSS receiver utilizes an antenna structure that two or more antennas that are spaced apart from their neighboring antennas by less than 1 wavelength of a GNSS satellite carrier signal of interest. The receiver calculates the orientation of the antennas directly from differences in the carrier phase angles measured at the two antennas, without resolving integer carrier cycle ambiguity. | 04-21-2011 |
20110102254 | CENTIMETER POSITIONING USING LOW COST SINGLE FREQUENCY GNSS RECEIVERS - A global positioning system includes a base GNSS receiver that determines position and carrier phase measurements for GNSS satellites in view and a rover GNSS receiver, which is a single frequency receiver that captures GNSS satellite signals transmitted in the single frequency band during a capture window from a plurality of GNSS satellites, the plurality being large enough to provide a carrier phase data set from which a solution to associated integer carrier phase ambiguities is over determined. The system determining from the captured signals, a search space associated with the satellites in view, the code phase delays and associated position uncertainty. The system resolving the integer carrier cycle ambiguities using double difference carrier phase measurements associated with signal power values that are over a predetermined threshold value. The system resolving the carrier cycle ambiguities over the capture window to a single solution set and determining the position of the rover GNSS receiver to an accuracy within centimeters using the resolved carrier phase measurements. | 05-05-2011 |
20130328711 | ANTI-JAMMING SUBSYSTEM EMPLOYING AN ANTENNA ARRAY WITH A HORIZONTAL CIRCULAR RECEPTION PATTERN - An anti-jamming subsystem for jamming signals originating along the horizon includes a two-dimensional horizontal array of antennas that effectively has a horizontal circular reception pattern for receiving signals originating along the horizon and a antenna that has a half hemispherical reception pattern and an upward looking view of the sky. The subsystem utilizes associated phase information to actively combine the signals received by the respective antennas in the array, to produce one or more anti jamming signals with narrow beams in the directions of the jammers. The subsystem combines the anti jamming signals with the signals received by the reference antenna, to produce signals for further processing in which the interference from the jamming signals originating along the horizon is minimized without adversely affecting the signals received by the reference antenna from at least higher elevation satellites. | 12-12-2013 |
20140125520 | ANTI-JAMMING SUBSYSTEM EMPLOYING AN ANTENNA WITH A HORIZONTAL RECEPTION PATTERN - An anti-jamming subsystem for a jamming signal originating along the horizon includes an anti-jamming antenna with a horizontal reception pattern constrained to receive signals originating along the horizon. The subsystem receives the signals from the anti-jamming antenna and a reference antenna, which has a half hemispherical reception pattern looking skyward. The subsystem utilizes associated phase information to phase shift the signals received by the anti jamming antenna and produce an anti-jamming signal, and combines the anti jamming signal with the signals received by the reference antenna to produce signals in which the interference from the jamming signal originating along the horizon is actively cancelled and the phase and timing information of signals received by the reference antenna from at least higher elevation satellites is preserved. The horizontal reception pattern of the anti-jamming antenna may be circular or directional toward a known jammer positioned along the horizon. | 05-08-2014 |