Abstract: A feature tracker for tracking a target includes an imaging sensor for imaging the target and a Kalman filter for generating predicted position, velocity and acceleration of the imaging sensor with respect to the target. The Kalman filter includes a state vector estimate of the position, velocity and acceleration of the imaging sensor, and a model for characterizing the target. The model characterizes the target by using at least one bivariate Gaussian function for the target. The Kalman filter includes a Jacobian matrix defined as a partial derivative of the model with respect to the state vector estimate. The Kalman filter includes a gain matrix generated from the Jacobian matrix.

Abstract: An integrity monitoring system (IMS) monitors data upload errors, internal data processing errors, clock faults, and transmit signal distortions in a transmitter system. The IMS includes a receiver with an A/D converter that under-samples a multi-band RF signal to produce a composite, aliased IF digital signal. Individual signals are extracted from the composite signal via correlation with the appropriate spreading code. The resulting signals are evaluated to determine whether any signal distortion is present in the RF signals being transmitted, and data is extracted from the signals to perform checks of data uploaded to the transmitter system and data present in the transmitted RF signals that was generated within the transmitter system. The IMS also checks for clock faults in the transmitter system without requiring an independent timing reference by using clock phase information provided by the transmitter system's time keeping system.

Abstract: A communication system generates a constant-envelope composite signal containing at least two signals whose power levels, bandwidths, and/or data rates are independently controllable. Binary offset carrier (BOC) modulation is applied to the signals to be combined in the composite signal. The BOC modulated signals are then combined via interplex modulation to form a constant-envelope composite signal in which the constituent signals modulate different offset carriers. For example, real BOC modulation can be used to generate a ranging signal in edge portions of the transmission band of the composite signal, while complex BOC modulation can be used to generate a frequency agile data signal in a center portion of the transmission band. Such a signal can be used for full duplex communications in satellite crosslinks. The interplex modulation allows independent control of the power levels of the two signals while maintaining a constant envelope, permitting use of saturated RF amplifiers.

Abstract: A technique for combining a plurality of signals to form a multi-carrier constant-envelope composite signal includes generating a constant-amplitude inphase (I) composite signal based on a majority vote of a first set of signals and generating a constant-amplitude quadrature (Q) composite signal based on a separate majority vote of a second set of signals. The I and Q components of a carrier signal are respectively modulated with the I and Q composite signals and combined to form the constant-envelope composite signal. In the case where a single offset carrier code is a constituent of the constant-envelope composite signal, a scale factor is applied to one of the I and Q composite signals to equalize the power of the I and Q components of the offset carrier code.

Abstract: A transmitter employing a cryptographic algorithm and key generates and transmits a staggered pulse signal that includes a plurality of high-power pulses that are part of a pseudonoise (PN) code. The high-power pulses are separated by a group of low-power chips and the time interval between the high-power pulses is varied according to the cryptographic algorithm and key. A receiver, employing a corresponding cryptographic algorithm and key receives the signal and correlates it with a locally generated code that is modified according to the cryptographic algorithm and key to detect the phase of the received PN code. The receiver also can include a matched filter configured according to the cryptographic algorithm and key to detect the sequence of high-power pulses in the received signal.

Abstract: An intervote modulator (10) includes a majority voting logic unit (12) and an interplex modulator (14). The majority voting logic unit receives plural signal codes (e.g., five codes x1, x2, x3, x4, x5) together with their respective target gains G1, G2, G3, G4, G5 representing the desired transmit power for the individual signal codes. The majority voting logic unit combines three of these five signal codes to form a majority vote composite signal while keeping the other two signal codes uncombined. The majority vote composite signal and the two uncombined signals are then supplied to the interplex modulator as signals s1, s2 and s3. The interplex modulator applies interplex modulation to signals s1, s2 and s3 to form the in-phase and quadrature components of the final composite signal. The majority voting logic unit employs a generalized majority vote involving an interlace of sub-majority votes determined on a chip-by-chip basis.

Abstract: A method of forming an antenna beam with a phased array antenna having an array of antenna elements includes selecting angular directions at which nulls are to be located in an antenna radiation pattern of the phased array antenna, computing a radiation shaping transformation as a function of the selected angular directions, and determining from the radiation shaping transformation an amplitude and phase distribution over the array of antenna elements that forms the antenna beam with nulls of the antenna radiation pattern at the selected angular directions. Computing of the radiation shaping transformation involves constructing a set of vectors corresponding to the selected antenna radiation pattern nulls, and computing a matrix whose product with each of the vectors is zero. The amplitude and phase distribution is determined from the matrix.

Abstract: A method and apparatus for simultaneously transmitting, at a common frequency, a plurality of signals on a plurality of beams from a phased array antenna involves forming composite signals that contain the plurality of signals. The composite signals correspond to respective antenna elements in the antenna array and include at least a first signal for transmission via a first transmit beam and a second signal for transmission via a second transmit beam. The phases of the composite signals are a function of signal modulations of the first and second signals and phases of the respective antenna elements required to form the first and second transmit beams. By digitally forming the composite signals, taking into account the modulation phase and beam-forming phase of each signal at each antenna element, hardware requirements are reduced and efficient, saturated amplifier can be employed.

Abstract: A new signal format that allows sharing of spectrum with CDMA signals with a minimum amount of mutual interference and a maximum amount of processing gain. The method including the step of coherently frequency hopping a narrow band signal adapted to minimize interference with a main lobe of the CDMA code over the allocated bandwidth. A particular application of this provides a method for enabling a global positioning device adapted to receive an allocated bandwidth to directly acquire a to P(Y) code when an associated C/A signal is effectively jammed.

Abstract: A transmitter employing a cryptographic algorithm and key generates and transmits a staggered pulse signal that includes a plurality of high-power pulses that are part of a pseudonoise (PN) code. The high-power pulses are separated by a group of low-power chips and the time interval between the high-power pulses is varied according to the cryptographic algorithm and key. A receiver, employing a corresponding cryptographic algorithm and key receives the signal and correlates it with a locally generated code that is modified according to the cryptographic algorithm and key to detect the phase of the received PN code. The receiver also can include a matched filter configured according to the cryptographic algorithm and key to detect the sequence of high-power pulses in the received signal.

Abstract: An intervote modulator (10) includes a majority voting logic unit (12) and an interplex modulator (14). The majority voting logic unit receives plural signal codes (e.g., five codes x1, x2, x3, x4, x5) together with their respective target gains G1, G2, G3, G4, G5 representing the desired transmit power for the individual signal codes. The majority voting logic unit combines three of these five signal codes to form a majority vote composite signal while keeping the other two signal codes uncombined. The majority vote composite signal and the two uncombined signals are then supplied to the interplex modulator as signals S1, S2 and S3. The interplex modulator applies interplex modulation to signals S1, S2 and S3 to form the in-phase and quadrature components of the final composite signal. The majority voting logic unit employs a generalized majority vote involving an interlace of sub-majority votes determined on a chip-by-chip basis.

Abstract: A method for generating a global positioning signal from a space based craft including the steps of generating a plurality of binary modulating signals using a waveform generator; separately modulating an in-phase component of a desired carrier of the global positioning signal to be generated with at least a first binary, modulating signal selected from the plurality to generate at least one corresponding in-phase modulated signal component; separately modulating a quadrature component of the carrier with at least a second binary modulating signal selected from the plurality to generate at least one corresponding quadrature modulated signal component; and, combining the at least one in-phase modulated signal component and the at least one quadrature modulated signal component to generate the global positioning signal; wherein the global positioning signal has a constant envelope.

Abstract: Improved performance in an electro-optical tracker is achieved by incorporating range measurements. Further, the tracker uses a Kalman filter in which the target is modeled as the superposition of two Gaussian ellipsoids in space and projected onto an image plane.

Abstract: Improved automated fire control apparatus includes servomotor positioned weapon(s), range-determining radar, optical sight and controller, and a data processor. Multiple, improved feedback network organizations are provided to control the optical sighting path vis-a-vis gun mount for automated lead angle implementation under overall gunner supervision. Thus, for example, optical line of sight deflection is controlled, inter alia, by radar antenna positioning, target flight projection computations as well as manual gunner signal entry.