Abstract: Apparatus and method for sonar or radar target tracking. Digital apparatus nd techniques are employed. A variable delay is used for beam steering.

Abstract: A radar detection system with four transducers accurately determines the azimuth angle of a radar emitting object. The three strongest signals from the four transducers are combined to generate two differential signal values. A table is provided which contains angle of arrival values associated with all possible combinations of the two differential signal values. To determine the angle or arrival of a particular object, an index value is derived from the corresponding pair of differential signal values, and that index value is used to select the record in the table with the angle of arrival of the object, relative to the transducer which received the strongest signal. The table also stores a signal measurement correction for each combination of the two difference signal values. The signal measurement correction is to adjust the measured signal strength when calculating the distance of the object from the radar detection system.

Abstract: An antenna beam boundary detector for a sectorized cellular system is disclosed. The difference in signal level received by a main directional antenna and a broad beamwidth antenna is determined by detecting a modulator signal locally impressed on the signal received by the broad beamwidth antenna. The signal level difference factor is the directional antenna beam boundary when the two antennas are correlated. Interferometer effects are cancelled by detecting both amplitude and phase modulation of the locally impressed modulation.

Abstract: A novel radio receiver capable of simultaneously and instantaneously determining the frequency and azimuthal and elevational position of many radio signal sources is disclosed. The invention makes use of an antenna array and associated beamforming networks capable of producing an omnidirectional reference signal, and a directional signal in which amplitude depends upon the relative elevational position of the radio frequency source and complex phase depends upon the relative azimuthal position of a radio frequency source.The use of a two-dimensional compressive receiver in one embodiment provides a way for instantaneously and reliably producing the Fourier transform of these signals, allowing accurate and continuous measurement of phase and amplitude difference. The antenna geometries disclosed additionally provide such signals for a wide input bandwidth.

Abstract: An automatic direction finder antenna array having a plurality of pairs of oppositely positioned antenna elements arranged radially from a common center with each pair forming a cardioid radiation pattern when energized. Switching apparatus energizes successive antenna pairs to produce a rotating cardioid pattern but with the cardioid being switched back and forth 180.degree. at a higher switching frequency when each pair of antennas is energized during the rotating function. The antenna AX whose output bears the lowest ratio R to the output of its oppositely positioned antenna is determined as well as the antenna AZ having the largest output signal VZ. The precise angle of reception of a received signal is then determined from AX, AZ, and R.

Abstract: A radio direction-finding system comprises at least two adjacent, coplanar rectilinear antenna arrays (ARR.sub.1, ARR.sub.2) which face in different directions; phase measurements are performed on pairs of antennae of different spacings (ANT.sub.C /ANT.sub.1 -ANT.sub.N) in each array in order to derive the direction of incidence in the plane of the arrays and/or the direction of incidence with respect to said plane, e.g. bearing (.theta.) and elevation (.beta.) respectively. To reduce the number of channels required for resolving ambiguity in the phase measurement on the widest-spaced antenna pair (ANT.sub.C /ANT.sub.N) in each array, ambiguity is resolved as far as possible with more closely spaced pairs in each array and finally resolved on the two arrays jointly by amplitude comparison of signals received by the two arrays, even though the accuracy of the amplitude comparison may be insufficient to resolve ambiguity in the arrays separately.

Abstract: In a direction finder operating according to the Watson-Watt principle and having two separate receivers (3, 4) of the same type and of simple construction for the signals of the two crossed directional antenna systems (A, B, C, D), the vectorial simulation signals VN in a transmission line for intermediate frequency antenna signals are compared to vectorial rectified signals VV in order to compensate the phase shift caused in both receivers by means of an adjustable phase shifter (21). The vectorial signals VV are selectively derived from the antenna signals as sum signals or difference signals. In one embodiment, a reconstructed phase signal is obtained by reverse pulse control in a direction finding ellipse generator (24, 25) having two outputs on the basis of the difference between the vectorial rectified signal VV and the rectified vectorial simulation signal VN.