Abstract: A radar system including a main antenna and a smaller auxiliary antenna, the main antenna having a radiation pattern with a main lobe and relatively small sidelobes, and the auxiliary antenna having an omnidirectional radiation pattern. A received signal in the sidelobes of the main antenna and the corresponding received signal of the auxiliary antenna are spectrally divided by sets of bandpass filters with the signals of corresponding ones of the bandpass filters being processed to null out a signal such as a jamming signal received via a sidelobe of the main antenna pattern. The processing includes inphase and quadrature detection of a partially cancelled signal with the resulting complex error signal being applied as a modulation of the signal of the auxiliary antenna to be subtracted from the signal of the main antenna to produce the cancelled sidelobe signal.

Abstract: A sundial is described using a mirror to reflect an indexing spot of sunlight onto the back of a translucent dial face that is marked with time and date indicia. Adjustments are provided so that a sundial designed for any location can be used in another location and still provide accurate zone time and date.

Abstract: A sensitivity velocity control program in a surveillance radar for distinguishing wanted moving targets from unwanted moving targets by processing radar target return data and having prestored evaluation criteria for accepting/rejecting the moving targets. The radar target return signals are processed to determine their true radial velocity and apparent radar cross section. The program evaluates these measurements based on a look-up table of preselected acceptable levels of minimum true radial velocity for each apparent radar cross section. The program declares a target acceptable when its radial velocity matches or exceeds the preselected minimum radial velocity for that radar cross section stored in a computer memory. The acceptance criteria relates to the type of target (aircraft, missile, bird, etc.) being accepted or rejected. In general, the criteria accepts large targets having low to high radial velocities.

Abstract: A radar system adapted to operate with a selected one of a plurality of pulse repetition intervals to produce a corresponding train of transmitted pulses of radio frequency energy in response to a train of trigger pulses and to receive returns from objects in response thereto, with returns from stationary objects producing signals with the same phase shift relative to the phase of a reference signal. The system includes a switching circuit responsive to a signal representative of the selected one of the pulse repetition intervals, for producing charge controlling signals with time intervals between the charge controlling signals and the trigger pulses being selected in accordance with the selected one of the pulse repetition intervals. A pulse forming network, is provided for storing energy in response to the charge controlling signals and for providing output pulses in response to the trigger pulses.

Abstract: A radar system including an azimuthally scanned radar wherein the radar receives echo signals during each of a succession of azimuthally scanned directions of the radar receiving beam. Sequences of samples of data of received echo signals are stored with sets of samples relating to a common range being utilized for developing weighting factors for weighting received echo signals as a function of range. Thereby, dynamic fluctuations in signals strength because of clutter are reduced.