Abstract: The present invention relates to a target location method, and more particularly to such a system using passive listening devices to determine the range, course and speed of one or more targets simultaneously. The invention may be used effectively against targets which emit either continuous or pulsed electromagnetic energy signals.

Abstract: A near-range personnel beacon locator apparatus utilizing a tuned tank circuit to receive the emitted signal from an activated personnel beacon. The detected signal is applied to a D.C. amplifier to provide a D.C. level which drives a controlled variable duty cycle timer for driving a light emitting diode indicator.

Abstract: A sidelobe canceller in which the undesired signals in the main antenna channel are cancelled at RF using signals from multiple auxiliary antennas, where each auxiliary antenna signal has been weighted in a vector modulator while at RF. The weighting is determined in a single wideband IF loop by multiplexing the multiple auxiliary antenna signals through the same auxiliary receiver, correlator and demodulator. The demodulated output signal from each auxiliary antenna is sampled and retained as a weighting to adjust the vector modulator for the corresponding auxiliary antenna. A timing and control circuit coordinates the multiplexing and sampling functions.

Abstract: An antenna for the short-range reception of an emitted signal comprises at least two independent sectors for the coarse location of an emission-beam source in two predetermined directions. Each sector is constituted by a waveguide having a single open face oriented in the intended direction of surveillance. A microwave diode is placed within each sector at right angles to, and at the geometrical center of, the supporting wall of the waveguide which is associated with the diode. The frequencies detected by the antenna are within the range of 10.sup.9 Hz to 30.times.10.sup.9 Hz.

Abstract: A system is disclosed for locating missing vehicles. Each vehicle broadcasts a locator signal when queried from a central station by an encoded call signal having a code characteristic of the vehicle. Indicators responsive to the locator signal are provided to determine the location of the missing vehicle.

Abstract: The present invention provides a method and apparatus for effecting, in a ssive manner, the acquisitioning of a broadband barrage jammer type radar target, by detecting the differential delay between the barrage signal as received at a predetermined location over direct and indirect paths and producing a signal distinctly identifying the location of the jammer target relative to the receiving station. More specifically, the present invention includes means for generating reference pulses of varying frequency which are utilized in determining the phase relationship which exists between each of these reference pulses and the corresponding frequency component of the jammer signal as received over the direct path to the target.

Abstract: A circuit for speed measurement of vehicles according to the Doppler-radar principle wherein a Doppler-useful signal is evaluated in a computer to which such signal is infed by means of a threshold value switch. A single sideband modulator is provided, at the input side of which there is supplied the Doppler-useful signal and also a high-frequency signal produced by a high-frequency oscillator. The output side of the single-sideband modulator is connected with the input of a phase-locked loop, the output signal of which is converted into the original frequency band of the Doppler signal by means of a demodulator connected at its output side with the input of the threshold value switch.

Abstract: Multiple interference signals in an electromagnetic wave communication system are individually discriminated against by a beamport sidelobe canceller comprising a multichannel auxiliary system in which spatial filtering of the angular sectors of interest is performed prior to sidelobe cancellation. Each spatial filter of the auxiliary system has its own adaptive control and only those interfering signals appearing in its assigned sector are operated on by that loop. The output of the main communication system receiver is summed with the outputs of the auxiliary system channels to produce a system output and an adaptive control loop feedback signal. The feedback signal initiates the generation of a cancellation signal in any adaptive control loop in which correlation of interference signals occur in both the main communication system received signal and the signal received by the auxiliary system channel to which that loop is connected.

Abstract: Precise azimuthal alignment of troposcatter system antennas is achieved by centering on the great circle, the combined pattern of intercepting beams from two troposcatter antennas. The combined antenna pattern is determined to be centered on and symmetric about the great circle when the Doppler spectrum on a received signal is symmetric about zero Doppler shift. The alignment procedure comprehends antenna manipulation, initially with both beams focussed and subsequently with one beam defocussed, until the desired Doppler spectrum condition is obtained. The requisite Doppler information is derived and processed by novel cross correlation techniques and data processing procedures.

Abstract: 4. A radar disabling means, including:A plurality of individual pieces of radar reflective chaff, each having a tear-drop shape.

Abstract: In a Loran Receiver that receives radio frequency (RF) signals from a master beacon and at least two slave beacons (also called secondary transmitters) and converts the received signals into hyperbolic coordinates that locate the position of the receiver with respect to the beacons and a programmed computer controls modes and sequences of operation of the system, these modes being generally the beacon pulse search mode, front edge/zero crossing location mode and the zero crossing track mode, received beacon pulses are searched and identified by the following technique: all received signals are repeatedly sampled at the beacon group repetition interval (GRI) in a regular sampling pattern in which the sampling rate is greater than the beacon pulse rate, each sample interval being only a small portion of a beacon pulse RF excursion; the samples are hard limited and assigned a value of plus or minus, depending upon whether they exceed a threshold, and these plus-minus patterns are accumulated over many GRIs and s

Abstract: The present invention relates to a method of cophasing the feed elements of a transmitting or a receiving phased array antenna. To cophase a transmitting antenna, the method entails transmitting a lower sideband and an upper sideband signal from a first and a second one of the feed elements, respectively, while transmitting a carrier signal used to generate the sideband signals on all other feed elements of the array. At each receiver the reference phase angle between the received sideband signals is measured and stored. The above step is sequentially repeated for the first and a third, the first and a fourth, etc., one of the feed elements, and the phase angle measured, subtracted from the reference phase angle, and stored. With the above method, the phase angle between each feed element and the second one of the feed elements is determined and stored and subsequently transmitted back to the transmitter for use in transmitting signals to each receiver.

Abstract: This invention relates to a focused synthetic array wherein a different signal from a crossed beam antenna is converted to a bipolar video signal and applied as the input to a synthetic array processor. In another embodiment of the invention there is a separate reduction of each beam output from a crossed beam antenna to bipolar video signals with a separate application of asymmetrical amplitude weights to the two bipolar video records and a subsequent subtraction in the course of synthetic array processing.

Abstract: A double loop receiver used in conjunction with a transmitter broadcasting at low frequencies as a vertical magnetic dipole. The two loops are connected with their planes parallel in a resonant circuit, thereby cancelling atmospherics generated by distant thunderstorms and allowing the receiver to receive only the signal produced by the near transmitter. The loops are rotated around a horizontal axis perpendicular to the connecting line between the loops until a maximum signal is obtained. The direction of the connecting line is varied until the maximum signal shows the gradient and the direction to the transmitter. By noting the position of the loops and the loop angles with respect to the horizontal, the position of a transmitter buried in the ground can be determined. This system has particular utility in locating lost miners buried in a cave-in. Additionally, the double loop receiver concept can be used to detect subsurface ore deposits.

Abstract: An antenna for radio frequency signals including a two flat faced phased arrays and ground plane system therebetween where transmission lines join the antenna planes to electronic control packages such that there is provided proper phase shift, final amplification and timing for retransmission by one of the antenna planes in a preselected direction, and where the signals are space fed to the other antenna plane by a feed system.

Abstract: In a multiple antenna array including null steering apparatus of the type utilizing a reference signal generator for preventing a null on a desired signal, weight oscillation eliminating apparatus for shifting the phase of the reference signal to make it generally equal and opposite to the desired signal so that weight oscillation of the system is eliminated.

Abstract: In a radar system employing an array antenna and microwave circuitry coupled thereto for developing sum and difference signals, a correction circuit utilizes the sum and difference signals for providing increased accuracy to elevation and azimuthal angle measurements of wide bandwidth radar signals. A correction is applied to the difference signal by subtracting therefrom a weighted time derivative of the sum channel, the weighting being proportional to the boresight error slope and the sines of the elevation and azimuth angles.

Abstract: The position of the electron beam axis of the central gun of an in-line tube is determined by moving the tube relative to a dynamic, multipole magnetic field produced by an electro-magnet mounted about the tube neck until a dot is displayed on the display screen. The line passing through the center of the field and the dot on the display screen defines the position of the beam axis and reference points related to that line are then provided on the tube envelope which locate the deflection unit so that its axis coincides with the beam axis.

Abstract: A power divider and modulator is disclosed comprising a HF signal source which supplies a carrier signal to a pair of 1/4.lambda. transformers each terminated with a variable impedance, whose impedance value is controlled by a modulating signal from a signal source. The amplitude of the carrier signal is modulated by a signal proportional to the sum of the two modulating signals to obtain a reflection free termination at the output of the HF signal source.

Abstract: Method of determining the direction of a radio source, wherein, using a circular array of aerials, a sinusoidal phase graph is determined and the direction of the radio source relative to a reference direction is determined from one or more zero crossings of the phase graph.