Abstract: A radar target velocity estimator apparatus and method for computing a radial velocity of radar targets from differences in Doppler frequency shift between pulse-returns of multi-pulse waveforms. The velocity estimator uses Doppler frequency shift which is obtained from a finite impulse response (FIR) filter in combination with logarithm tables stored in read-only-memory (ROMs) to calculate the target's velocity. The estimation process requires the calculation of each complex FIR filter value twice during a pulse repetition interval; once for returns of a leading set of radar pulses and then for a trailing set. The estimated velocity is proportional to the phase difference between each corresponding pair of filter values. The estimate is a function of the arctangent of the quotient of the in-phase component of the complex value divided by the quadrature component.

Abstract: A cartesian to polar coordinate converter using a cordic magnitude circuit for estimating the magnitude and angle of a vector from its known orthogonal components. The vector is described in cartesian coordinates by the complex number I+jQ. The magnitude of the vector and its angle are approximated by an iterative process of successively rotating the vector toward one of the orthogonal axes and the cordic magnitude circuit is implemented in one very large scale integrated (VLSI) complementary metal-oxide semiconductor (CMOS) chip. In systems using a typical cordic magnitude circuit, accuracy increases in direct proportion to the number of rotations. The increase is accompanied by a need for an increased word size which results in a slower operating speed. The improved cordic magnitude circuit achieves higher precision without the need for a larger word size.

Abstract: A signal processing system, which operates in parallel with the outputs of sensors of an adaptive array, for quickly nulling multiple jammers. The processing system includes a set of parallel combiners and an apparatus for updating a signal weight which is applied to the sensor outputs. The parallel combiners mix a weighing function with each sensor output and provide a resultant output signal which has been cleared of interference from jamming. Part of the resultant signal is fed to the apparatus for updating the signal weighing function for further mixing with sensor outputs. The parallel operation of the combiners with each sensor output provides fast nulling effects.

Abstract: An optical encoder device for use with a variable range mark display. An operator rotatable cylindrically shaped encoder wheel with longitudinal slits is panel mounted. Two light-emitting diodes are positioned outside the wheel opposite two phototransistors located inside the wheel. The light-emitting diode-phototransistor pairs are spaced at a forty-five degree angle from one another from the center of the wheel. Rotation of the wheel interrupts the light path between the light-emitting diodes and phototransistors producing two output signals. For one direction of rotation the first signal leads the second while for the other direction of rotation the first lags the second. A circuit is disclosed which determines from the output signals the direction of rotation and produces a count indicative of the amount of rotation.

Abstract: A variable range marker device for use with a PPI radar with digitized video displayed in non-real time. The position of the range marker is initially operator determined by rotation of a knob mechanically linked to an optically encoded disc. Optical sensors produce a digital output indicative of the disc rotation angle and range mark position as a distance from the center of the radar display screen. A counter is preset with the digital ouput at the start of each sweep and decremented once each range cell until a count of zero is reached at which time an unblanking pulse is produced. A numeric display of range is produced by dividing the number of range cells to the range mark by the range setting, scaling according to chosen units of measure, and displaying the result with a LED display, the computations being performed by a processor controlled by a permanently programmed memory. The range mark stays on target as the range scale is changed.