Abstract: A circulator for duplexing microwave signals is shown to consist of a pair of folded magic-T hybrid junctions with a nonreciprocal phase shift section disposed between the parallel ports of such junctions, the nonreciprocal phase shift section being made up of U-shaped ferrites supported between the insides of H-plane walls in a rectangular waveguide and U-shaped permanent magnets adjustably supported on the outsides of the H-plane walls so that the magnetic flux in the U-shaped ferrites may be changed as required.

Abstract: A method of operating a pulse Doppler radar to increase the probability of detection of an airborne target is shown to consist of transmitting interrogating pulses with a high pulse repetition frequency and processing received signals using any conventional pulse Doppler technique for echo signals having a Doppler shift frequency outside the spectrum of Doppler shift frequencies of clutter and using a DPCA technique at a submultiple of the pulse repetition frequency for echo signals having a Doppler shift frequency within the spectrum of Doppler shift frequencies of clutter.

Abstract: An angle encoder for determining the pitch (or yaw) angle of a gyroscopic mass with respect to the pitch (or yaw) axis of a missile in flight is shown to be the combination of: (a) an optical encoder pattern disposed on the periphery of the gyroscopic mass, such pattern preferably being divided into a substantially equal reflective portion and a nonreflective portion; (b) an optical sensor arrangement having a limited field of view, such arrangement being mounted on the body of the missile to provide a first signal whose level is indicative of the reflective or nonreflective portion in the limited field of view; and (c) circuitry for converting the first signal into a signal indicative of the pitch (or yaw) angle of the missile.

Abstract: An integrated circuit memory having a plurality of row lines; a plurality of select lines; a plurality of output lines; a plurality of memory cells; each pair of memory cells having common outputs coupled to a select one of the plurality of output lines and common address inputs coupled to a select one of the plurality of row lines, wherein ambiguity of which memory cell of the pair of memory cells to be selected, being coupled to a select one of the plurality of row lines and a select one of the plurality of output lines, is determined by two selected ones of the plurality of select lines coupled thereto. Also provided is a first decoder, responsive to an input address, for enabling a select one of the plurality of row lines, and a second decoder, responsive to the row lines and to the input address, for enabling a select one of the select lines which corresponds to pairs of memory cells with an enabled row line.

Abstract: A control system for a cannon-launched projectile carrying explosive squibs is shown to comprise: (a) a first control computer, responsive to the range and bearing of a selected ground target, to compute an ideal ballistic trajectory between an artillery piece and such target and to calculate the line of sight between the artillery piece and points on such trajectory; (b) an infrared beam generator and scanner for scanning, under the control of a first clock, such beam in a predetermined pattern centered on the calculated line of sight; (c) a sensor carried on the cannon-launched projectile for detecting when the infrared beam irradiates such projectile; a second clock on the cannon-launched projectile operating synchronously with the first clock to indicate the position of the infrared beam when the cannon-launched projectile is irradiated; and (d), a firing controller for selecting and firing one, or more, explosive squibs to force the cannon-launched projectile toward the ideal ballistic trajectory.

Abstract: A low cost electronic navigation system including a Loran receiver and a marine radar unit adapted to receive vessel position information from the Loran. A computer within the radar unit uses successive Loran outputs to display vessel heading and the bearing of objects of interest such as other vessels or waypoints in graphic and numeric form. The navigator may accurately determine the bearing of such objects of interest in magnetic or true form. Other modes are of particular use when the navigator is interested in using the system to maintain a desired course, to avoid obstacles, or to determine if and by how much he must change his present course to return to the desired course.

Abstract: An electronic switching arrangement is shown to consist of an effective balanced pi configuration using series and shunt FETs and transformer coupling so that the impedances seen by such FETs are optimized.

Abstract: An improved microwave frequency signal source using a single frequency offset technique which increases the frequency range of an indirect frequency synthesizer to twice the highest operating frequency of the programmable digital frequency divider in the loop includes a voltage-controlled oscillator (VCO) operating within a predetermined microwave frequency band and phase-locked to a reference oscillator operating at a reference frequency below microwave frequencies. The offset loop signal is developed by heterodyning the voltage-controlled oscillator (VCO) output signal with a microwave signal whose frequency is located at the center of the predetermined microwave frequency band of the VCO to form a signal at an intermediate frequency (I.F.) within the frequency range of a programmable digital frequency divider.

Abstract: A high speed full adder circuit is shown to include logic circuitry responsive to the levels of the two digital signals to be added for: (a) immediately producing an appropriate carry signal when the levels of the digital signals are the same; and (b) inverting the carry signal into such adder when the levels of the digital signals differ.

Abstract: An array antenna is shown, the disclosed antenna having an effective cross-sectional area which is lower than its physical cross-sectional area. The reduction in effective cross-sectional area is effected by: (a) fabricating the reflector for the array antenna from spaced wires; and, (b) curving the entire array and its reflector.

Abstract: A method of maintaining the operational characteristics of an IMPATT diode is shown to consist of the steps of sensing the peak diode voltage and using such voltage to control the current through the IMPATT diode so that the peak diode voltage is kept constant.

Abstract: Apparatus and method for dynamically testing logic circuits transparent to their normal operation without placing restrictions on the logic circuit design. The apparatus is a swap scan register including an operational register for storing operational data and a test register for storing test data. The operational and test registers operate independently of each other. A swap circuit enables exchanging the operational and test register contents. According to the method disclosed after test data is stored in the test register, the operational register is interrupted and its contents swapped with the test register for one clock cycle. The test and operational registers are then swapped again to restore the original operational data to its pre-interrupt state and to provide test results in the test register.

Abstract: An arrangement to couple at least one I/O device to the main bus between a CPU and a main memory in a digital computer system is shown to include a random access memory made up of a dedicated part of the main memory and control circuitry to allow access between addresses in the random access memory and either the CPU or the at least one I/O device, such circuitry being arranged to give priority of access to the CPU except when data is actually being transferred from the I/O device and the random access memory.

Abstract: A receiver including two optimizers for demodulation, sampling and quantization of received QPSK digital data. One optimizer adjusts the phase of a reference signal used for demodulating the QPSK data into baseband in-phase and quadrature channels and another optimizer adjusts a sampling clock used to sample and quantize the baseband channels. The reference signal and the sampling clock are dithered in quadrature. Variations in the amplitude of the quantized data extracted by an eye quality monitor. Each optimizer multiplies the eye quality monitor output by a corresponding dither clock and integrates to form an error signal. Phase shifters, responsive to corresponding error signals and dithered clocks, adjust the phase of the demodulation reference signal and sampling clock. The data quality signal monitor translates the magnitude of the quantized data signals to a common set of signals for each state of the data signal.

Abstract: A gimbal arrangement for supporting an antenna element steerable in pitch and yaw is shown to include a generally spherical bearing supporting such element, such bearing having a slot formed therein and aligned with the pitch axis to engage a pin affixed to the antenna element and a pitch and a yaw cam assembly independently actuable to steer the antenna element in pitch and yaw.

Abstract: A method of compensating for the difference between static and sliding friction in an inertially stabilized platform is shown to comprise the steps of first detecting when static friction exists and then changing the torque applied to the inertially stabilized platform to eliminate the effect of static friction.

Abstract: A cryogenic refrigerator operating on the Split-Sterling cycle principle is disclosed. The refrigerator has a seal-less expander and achieves efficient operation without the use of external control apparatus. This is accomplished by sizing the expander so that two pressure differential forces developed across a displacer in the expander are approximately equal in magnitude. For efficient operation, the expander's gas flow rate is selected to provide the proper time delay between the two pressure differential forces.

Abstract: A subtractor for an N-bit digital number comprising N cascaded cells, each cell being adapted to effect subtraction by two's complement arithmetic and to provide a carry-out signal in accordance with the level of two bits being processed and a carry-in signal.

Abstract: An adder/subtractor wherein N/2 two bit adders are connected to allow the addition of numbers having N bits, each one of the two bit adders having associated control circuitry adapted: (a) to cause each two bit adder either to add applied bits directly or to add one applied bit and the "two's complement" of the other bit; and (b) to electrically separate any selected ones of the two bit adders from the others.

Abstract: A multibit digital adder wherein a proper carry-out signal is generated simultaneously in different parts of such adder.