Navcom Technology, Inc.

Deere + Company

Magnavox Electronic Systems Company

Leica Geosystems Ag

Hughes Electronics Corporation

The Directv Group, Inc.

Jerry Eugene Knight

Richard Gerald Keegan

Charles Robert Cahn

Thomas A Stansell, Jr

David Man Kui Li

Ronald R Hatch

Thomas Atlee Stansell

Richard G Keegan

David Man Li

A signal receiver receives a time-domain signal that includes a plurality of pilot tones at a plurality of corresponding frequencies. The time-domain signal is transmitted from a transmit location. The signal receiver extracts from the received time-domain signal pilot phase values corresponding to the pilot tones. The signal receiver computes a signal propagation time of the received time-domain signal by fitting an interpolation function to residual pilot phase values, corresponding to the extracted pilot phase values, and determines a slope of the interpolation function. The signal receiver computes a range between the transmit location and the signal receiver by multiplying the computed signal propagation time with the speed of light.

Navigation using range measurements to OFDM transmitters

A signal receiver includes an antenna interface for receiving signals from an antenna, analog signal processing circuitry coupled to the antenna interface for processing the received signals to produce filtered signals, sampling circuitry to sample the filtered signals so as to produce digitized received signals, a digital compensator to receive the digitized received signals and compensate for non-uniform group delay introduced by the analog signal processing circuitry to produce compensated digitized received signals, and a digital processor to process the compensated digitized received signals so as to produce a result.

High frequency signal receiver with self-calibrated group delay compensation

A signal receiver includes an antenna interface for receiving signals from an antenna, analog signal processing circuitry coupled to the antenna interface for processing the received signals to produce filtered signals, sampling circuitry to sample the filtered signals so as to produce digitized received signals, a digital compensator to receive the digitized received signals and compensate for non-uniform group delay and amplitude distortion introduced by the analog signal processing circuitry to produce compensated digitized received signals, and a digital processor to process the compensated digitized received signals so as to produce a result.

Signal receiver with group delay and amplitude distortion compensation

An adjustable code generator is configurable to generate any of a plurality of spread-spectrum code signals. The adjustable code generator includes a feedback polynomial mask table to contain a set of feedback polynomial masks. Respective feedback polynomial masks of the set correspond to respective spread-spectrum code signals of the plurality of spread-spectrum code signals. The adjustable code generator also includes control logic to select any of the feedback polynomial masks of the set contained in the feedback polynomial mask table, and further includes a shift register to provide, at an output, a respective spread-spectrum code signal that corresponds to a feedback polynomial mask selected by the control logic and to receive feedback generated using the feedback polynomial mask selected by the control logic.

Adaptive code generator for satellite navigation receivers

A satellite navigation device including a flexible radio frequency (RF) receiver is described. The receiver receives a signal that includes at least a first spread-spectrum signal from a first satellite. The receiver has a first channel that includes an analog-to-digital (A/D) converter to sample and quantize the signal and an automatic gain control (AGC) to adjust an amplification of the signal. The A/D converter has a first non-zero quantization threshold magnitude and a second non-zero quantization threshold magnitude. The AGC may adjust a gain in accordance with the first non-zero quantization threshold magnitude. The gain may correspond to a first pre-determined probability of a non-zero sample and the second non-zero quantization threshold magnitude may correspond to a second pre-determined probability of a non-zero sample.

Sampling threshold and gain for satellite navigation receiver

A satellite navigation device including a receiver having an adjustable code generator is described. The adjustable code generator is configurable to generate a set of spread-spectrum code signals. Each spread-spectrum code signal has a respective length corresponding to a repetition period. The set of spread-spectrum code signals includes first and second spread-spectrum code signals having distinct first and second lengths.

A satellite navigation device including a flexible RF receiver is described. The receiver receives a signal that includes at least one spread-spectrum signal from a first satellite. The receiver has at least a first channel that includes at least two sub-channel circuits. Each sub-channel circuit has at least a first signal generator and a first mixer to receive a respective frequency band in at least the one spread-spectrum signal from the first satellite. The first signal generator provides a respective first signal, having a respective first carrier frequency, to down convert at least a portion of the signal, using the first mixer, to an intermediate frequency that is common to the two sub-channel circuits.

Satellite navigation receiver signal processing architecture

A technique for minimizing or eliminating the effect of multipath signals in a receiver processing pseudorandom (PRN) code signals, such as in a global positioning system (GPS) receiver. The presence of multipath signals adversely affects both code measurements and carrier phase measurements of received PRN signals. One aspect of the invention provides for improved code tracking in the presence of multipath signals, by sampling the received code with a multipath mitigation window (MMW) (FIG. 25D) that results in a code error function (FIG. 25F) that reduces or eliminates the multipath effects. The MMW, which may be any of a number of preferred waveforms (FIGS. 35B-35E), provides a code error function that varies in opposite directions from zero at a desired tracking point (402), but assumes a nearly zero value when the MMW is advanced from the tracking or synchronization point by more than a small fraction of a code chip. Because of this nearly zero code error value on the early side of the desired tracking point, delayed multipath signals will have a corresponding code error function that is nearly zero (FIG. 25F) at the desired tracking point of the directly received signals, and the multipath signals will, therefore, have little or no effect on the desired tracking point and on code synchronization. The effects of multipath signals on carrier phase measurements are minimized by sampling the received signals, together with their possible multipath components, before and immediately after code transitions (vectors A and B, respectively). The vector relationship of the directly received (D) and multipath (M) signals is such that performing a vector average of the two types of samples (A and B) produces the directly received signal (D) and its correct phase, with many, if not all, of the multipath components (M) eliminated.

Mitigation of multipath effects in global positioning system receivers

Method and apparatus for improving the speed and accuracy of processing signals from global positioning system (GPS) receivers by ensuring access to GPS carrier signals that have been modulated with an encrypted P-code sequence. In one disclosed embodiment of the invention, GPS L1 and L2 signals are correlated with a locally generated P-code signal, bandpass filtered to enhance signal-to-noise ratio performance, and then cross-correlated to obtain a signal with an L1-L2 frequency component that facilitates the resolution of carrier cycle ambiguity. In another embodiment, received GPS signals are immediately converted to digital form, then digitally correlated with in-phase and quadrature components of a locally generated P-code signal. Signals resulting from the correlation are then integrated over timing intervals corresponding to a previously determined encryption period to provide in-phase (I) and quadrature (Q) samples. In one variant of this embodiment, the I and Q samples derived from the L2 GPS signal are digitally squared to obtain an L2 carrier. In another variant, I and Q samples derived from both L1 and L2 signals are cross-correlated to obtain a digital carrier with an L 1-L2 component. Tracking errors for the L1 and L2 P-code signals are computed using a similar digital technique.

Global positioning system (GPS) receiver for recovery and tracking of

A technique for smoothing pseudorange code measurements made in a global positioning system (GPS) receiver, with carrier phase measurements, over an extended time interval but without distortion that usually results from a divergence between code-derived pseudorange measurements and carrier-derived measurements. The basic principle of the invention is to remove ionospheric effects and Doppler effects from the pseudorange code measurements prior to filtering over an extended time interval. Removal of ionospheric effects may be effected by applying corrections received from a reference receiver, or may be accomplished using measured or modeled ionospheric data available to the receiver. The invention is applicable to differential GPS position finding using remote receivers having only a single-frequency capability, but is also applicable to stand-alone GPS receivers of any type.

Growing community of inventors

Long Beach, CA, United States of America

Jerry Eugene Knight