Raytheon Company

Lee M Savage

William Hale Wellman

Eric J Gudim

David Brent Wilson

John T Broad

Steven L Kaufman

Jack E White

William H Wellman

James E Henry

Ronak D Shah

Daniel A Hanevich

Loyra G Dirzo

Douglas E Fullmer

Jeffrey J Becker

A receiver operable to determine a geolocation of a radio emitter is disclosed. The receiver can identify a set of observations derived from signals emitted by the radio emitter. The signals can be detected via an antenna associated with the receiver. The receiver can identify an estimated location of the radio emitter. The receiver can calculate a cone angle complement for each observation in the set of observations. The cone angle complement can correspond to an ambiguity level of each observation. The receiver can sort the observations based on corresponding ambiguity levels to produce a set of sorted observations. The receiver can process, using a Kalman filter in the receiver, the set of sorted observations to iteratively refine the estimated location for determination of the geolocation of the radio emitter.

Emitter geolocation using sorted observations

A method for improving geolocation accuracy in a passive radar warning receiver, using synchronized data curve-fit and interpolation to asynchronous and noisy receiver and navigation measurements over observation periods that are extended to reduce inaccuracies caused by noise. The present disclosure yields synchronized data samples at intervals short enough that constant-rate equations are valid, even though the actual motions over the observation interval may be more complex and have higher-order dynamics. It reduces noise, synchronizes data samples, and is readily adapted to motions with variable acceleration. The method generates rate samples short enough to satisfy constant rate assumptions, yet fit data over intervals long enough to enhances measurement accuracy by reducing measurement noise.

Geolocating a remote emitter

A method for determining a FDOA of a pulsed waveform received by two sensors includes obtaining a respective plurality of in-phase and quadrature-phase (IQ) samples indicative of a pulse envelope of the received pulsed waveform. The method includes determining a TDOA responsive to a leading edge of a pulse of the pulsed waveform and obtaining a first cross correlation of IQ samples at a delay (d) closest to the TDOA, and respective second and third cross correlations at least one additional delay (d+1 and d&#x2212;1) on either side of the closest delay. The method includes refining the approximation of the TDOA according to an interpolation of amplitudes of the cross-correlation and determining a respective rate of change of cross-correlation phase (&#x394;&#x3c6;). The method includes approximating a straight line fit to the rates of change of cross-correlation phase (d&#x394;&#x3c6;/dt), the slope of the straight line representative of the FDOA.

Frequency difference of arrival (FDOA) for geolocation

Several types of noise limit the performance of remote sensing systems, e.g., systems that determine the location, color, or shape of remote objects. When noise detected by sensors of the remote sensing systems is known and well estimated, a Kalman filter can converge on an accurate value without noise. However, non-Gaussian noise bursts can cause the Kalman filter to diverge from an accurate value. Current approaches arbitrarily boost noise with fixed additive or multiplicative factors, which slows filter response and often fails to give timely results. Such noise boosts prevent divergence due to badly corrupted measurements. Disclosed embodiments eliminate a subset of noise measurements having the largest errors from a data set of noise measurements and process the remaining data through the Kalman filter. Advantageously, disclosed embodiments enable a Kalman filter to converge on an accurate value without the introduction of noise boost estimates.

Iterative Kalman filtering

A method and system for detecting and characterizing an input signal receive a signal having an in-phase (I) component and a quadrature-phase (Q) component. A first IQ sample of the signal is acquired at a first point in time, and a second IQ sample of the signal is acquired at a second point in time, Using one or more processors, a delayed complex conjugate multiply (DCM) is applied to the first IQ sample of the signal and the second IQ sample of the signal to produce a constant product having an in-phase (I) component and a quadrature-phase (Q) component. A signal magnitude and a signal frequency are determined from the Icomponent of the constant and the Qcomponent of the constant, using the one or more processors.

Signal detection and characterization

Accurate remote tracking of fixed objects from a moving platform requires overcoming platform noise. Such tracking becomes difficult when the only inertial reference (such as a central aircraft inertial navigation system) is remote from the sensor, which experiences non-measured angular movements due to airframe vibrations and flexing. In such a scenario, Kalman filtering cannot converge on a true value because all noise sources are not known. Current na&#xef;ve approaches arbitrarily boost noise with fixed additive or multiplicative factors. However, such approaches slow filter response and; thus, often fail to give timely results. Embodiments of the present disclosure derive inertial reference parameters to quantify noise of the sensor that is remote from the inertial reference. Advantageously, disclosed embodiments enable use of remote sensors with an existing inertial reference, rather than consolidating sensors and the inertial reference at a single location or providing inertial references at each sensor.

Kalman filtering with indirect noise measurements

A method for minimizing unwanted signal harmonics from at least one signal in a channel received through a monobit receiver, comprising: conditioning () the channel, determining () relative strength between two frequency components of a signal within the channel, and using that relative strength () to control () how the channel is conditioned. In other embodiments, a system for receiving signals in a channel and minimizing unwanted harmonics from those signals has a monobit receiver (), a channel conditioner (), and a feedback driver () determining relative strength () between two frequency components of a received signal and using that determination to control the channel conditioner in a way that urges the relative strength toward a desired value.

Monobit receiver spurious harmonics control method and system

An electronic circuit combines two or more individual wideband RF receivers or transceiver band circuits to produce a usable instantaneous bandwidth that is wider than the bandwidth of the individual band circuits. The electronic circuit overcomes the difficulties of combining bands to provide low signal distortion across the band edges and throughout the combined instantaneous bandwidth of the two or more individual band circuits. This electronic circuit utilizes an amplitude, time delay, and phase adjustment procedure that uses associated adjustable circuitry to eliminate misalignments between the two or more individual band circuits.

Band stitching electronic circuits and techniques

A signal repeater () includes a signal processing part () and a signal repeating part (). The signal processing part includes a converter () configured to receive an input signal and to convert the input signal into quadrature signals, and a processor () configured to process the quadrature signals to determine one or more characteristics of the input signal, and to compare the one or more characteristics of the input signal and a plurality of predetermined characteristics to generate a comparison result. The signal repeating part () is configured to selectively repeat the input signal as a repeated signal in accordance with the comparison result.

Growing community of inventors

Santa Barbara, CA, United States of America

Lee M Savage