Abstract: Systems and methods are provided for differentiating weapon fire from targets on the ground to an aircraft such that appropriate countermeasures can be taken. A plurality of shots from a target on the ground is detected from a sensor in the aircraft. Shots belonging to a single burst are correlated. A firing characteristic of the plurality of shots in the burst is computed. A weapon type is determined for the plurality of shots based on the firing characteristic.

Abstract: In a system for locating the position of a transmitter, a platform containing an antenna is moved through a measurement path. The frequency received by the antenna is measured at measurement points distributed along a measurement path. The frequency is measured by cross correlating coherent pulses of the received frequency signal. An inertial navigation system on the platform indicates the position of the measurement path. A computer determines estimated locations by non-linear least squares convergence starting from trial locations. The non-linear least squares convergence is based on the frequency equation for the received frequency ##EQU1## in which f.sub.0, is the transmitter frequency, V is the antenna velocity and r is the range of the transmitter. The computer evaluates a cost function derived from the frequency equation, for each location estimated by the non-linear least squares convergence and selects the estimated location with the lowest cost function as the best solution.

Abstract: In a system for locating the position of a transmitter, a platform containing an antenna is moved through a measurement path. The frequency received by the antenna is measured at measurement points distributed along a measurement path. The frequency is measured by cross correlating coherent pulses of the received frequency signal. An inertial navigation system on the platform indicates the position of the measurement path. A computer determines estimated locations by non-linear least squares convergence starting from trial locations. The non-linear least squares convergence is based on the frequency equation for the received frequency ##EQU1## in which f.sub.0 is the transmitter frequency, V is the antenna velocity and r is the range of the transmitter. The computer evaluates a cost function derived from the frequency equation, for each location estimated by the non-linear least squares convergence and selects the estimated location with the lowest cost function as the best solution.

Abstract: In a long base line interferometer system for determining the position of a transmitter, the phase differences between the signal received by the antennas at each end of the base line are monitored as the interferometer moves through a measurement path to obtain phase difference measurements distributed along the measurement path. A cost function involving measuring the sum of the squares of the differences between measured values and predicted values is determined for each of a set of trial location grid points and the grid point with the lowest cost function is selected as a starting point for determining the transmitter location by least squares convergence. In evaluating the cost function, the predicted values are obtained from the equation: ##EQU1## in which .o slashed..sub.0 is unknown phase offset and the X and Y coordinates of the transmitter are unknown. The least squares convergence is carried out by iteratively adding corrections to predicted values for the unknowns until convergence occurs.

Abstract: A multipath signal preprocessor which permits coherent bistatic radar detection with a single omnidirectional antenna is provided. The multipath signal preprocessor separates multipath signals received at an antenna into a strong path signal and a weak path signal. The received multipath signal after filtering, amplifying, and heterodyning is separated into in-phase and quadrature signal components. A constant magnitude signal estimate having approximately the frequency and phase of the strong path signal from the multipath signal is generated. An estimate of the amplitude of the strong path signal is generated from the received multipath signal amplitude. The estimate of the amplitude of the strong path signal is multiplied by the constant magnitude signal estimate having approximately the frequency and phase of the strong path signal to obtain an estimate of the strong path signal.