Abstract: A system for performing real time quantization and analog/digital conversion of an analog waveform operating with analog input signals over one gigahertz bandwidth is realized by utilizing a CRT type device in which the electron beam is deflected by the analog input waveform. The deflected electron beam strikes a fast phosphor screen and an externally positioned target consisting of light sensitive elements arranged in a discrete pattern detects and quantizes the signal. The output of the detectors feed an encoder resulting in a binary digital output waveform. The device accepts both unipolar and bipolar video waveform and has parallel output channels such that further circuitry to be employed can operate with reduced bandwidths.

Abstract: Uniform detection sensitivity along the periphery of an r.f. loop intruder detector system is realized by periodically electronically interchanging the input and termination ends of the system's leaky transmission line transmitting element. The intruder detector system comprises a length of leaky transmission line that encompasses the region to be protected, a receiving antenna within the protected region, an r.f. transmitter and a remotely located receiver and detector. R.F. energy is transmitted through the leaky transmission line and received by the receiving antenna and detector means to establish a normally quiescent field. Violation of the protected region by crossing the leaky transmission line disturbs the quiescent field condition and the intrusion event and the location is signaled by the detector. The effects of attenuation along the leaky transmission line are obviated by periodically switching the transmitter to alternate leaky transmission line ends.

Abstract: The intrusion detection capability of a guided wave radar intrusion detection system is selectively disabled in certain areas, such as gates or portals to permit ingress and egress of personnel and vehicles without affecting overall system performance and without requiring an independent detection system. This is realized by means of an integral system portal enable-disable device. Guided wave radar intrusion detection systems employ two parallel leaky transmission lines, one transmitting and the other receiving radar signals. Violation of the area between the leaky transmission lines by an intruder results in a signal that indicates the occurrence and its location. Gate areas are remotely enabled or disabled by a switching circuit that switches a segment of non-radiating transmission line into or out of the transmitting leaky transmission line in each selected gate region.

Abstract: A two stage transmission notch filter characteristic is achieved with one stage of microwave circuitry. Elimination of the second stage is accomplished by reflecting the microwave power back through a single stage device. Structurally, the adjacent ports of two 3 dB directional couplers are directly connected by delay lines of unequal delay times. The opposite adjacent ports of one coupler comprise the device input and output while the opposite adjacent ports of the other coupler are terminated in a manner that reflects microwave power back through the device. A phase shifter is inserted into one delay line for tuning and a non-reciprocal phase element is used to prevent reflected signals from emerging from the input port.

Abstract: Crossed field amplifier collector efficiency is improved by decreasing the ratio of electron velocities to r.f. signal wave velocity at the output end of the amplifier slow wave circuit. In a preferred embodiment of the invention this is accomplished by tapering the sole emitting cathode so as to increase the cathode-slow wave circuit spacing in the output end of the interaction region prior to the collector. Alternatively, an increasing r.f. signal phase velocity taper can be used to provide the required decreased electron velocities to r.f. signal wave velocity ratio.

Abstract: The passive receiver protector, AGC attenuator and sensitivity time control functions of a radar are combined in a single device which performs the functions in front of the radar low noise amplifier with relatively low loss. The receiver protector utilizes semiconductor diodes which operate as a power limiter during transmit and as precision attenuators during receive.

Abstract: Noise induced hunting is eliminated in successive ranged digital/analog converter bias correction circuits by means of a digital hysteresis circuit. The digital hysteresis circuit comprehends a first up/down counter that counts to its extremums from a pre-set intermediate state in response to enable and up/down input signals. For each extremum count an enable output pulse and a reset pulse is generated at the counter output. The enable output pulses are counted by a second up/down counter the output of which drives a digital/analog converter. Each reset pulse resets the first up/down counter to its pre-set state.

Abstract: Increased bandwidth in a waveguide lens antenna is achieved by altering the geometry of the stepped antenna guide plates in a manner that causes the net contribution of the antenna phase dispersion sources to result in zero average aperture phase error. Design equations are included for the fabrication of waveguide lens antenna having any desired degree of phase compensation. In principle, the plate geometry is configured to effect a given relationship between the components of phase error due to guide plate dispersion and the component of phase error due to the guide plate steps. When these components are equal and opposite zero average aperture phase error (maximum bandwidth operation) is achieved.

Abstract: The RF power and video modulation monitoring circuit of the invention provides the unique capability of monitoring the performance of a repeater/noise jammer countermeasures system when the system is operating in either the repeater or the noise jamming mode. In the repeater mode the systems noise level is measured in an unused portion of the countermeasures system frequency band to provide a monitor of system gain and antenna VSWR. In the noise mode crystal detection and threshold comparison provides an indication of RF power output. In either jamming mode the measurement of AC in the detected output provides a monitor of modulation.

Abstract: An automatic bias adjustment circuit for a successive ranged analog/digital converter (SRADC) that eliminates the need for manual bias adjustments and calibration inputs. The bias correction circuit comprehends dual flip flops that are triggered by selected comparators of the SRADC n bit parallel analog/digital converter. The flip flop output signals control up/down counters whose output bits drive digital/analog converter. The digital/analog converted signals are introduced back into the SRADC analog chain to zero bias errors in a particular sub-range. A disabling circuit prevents operation of the bias adjustment circuits for the first sub-range.

Abstract: High levels of R.F. power are controlled and switched by means of a hybrid switching network that employs an intermediate power level switch matrix in conjunction with a pair of 8.34 (nominal) directional couplers and a phasing network. The two directional couplers are connected in tandem by two equal length transmission lines to form a broadband quadrature 3dB hybrid. Switching is accomplished by selectively inserting a 180.degree. phase shift means into the lower power carrying transmission line. The phase shifting means can be a length of transmission line, a solid state device, or a Schiffman type phase shifter.

Abstract: A single blade proximity probe uses fiber optics to direct a laser output at turbine engine blades and to return the reflected light to an image intensifier probe which provides an output indicative of blade clearance. To enable the system to measure the clearance of a single blade tip on an operating turbine, a second light beam having a different wavelength from the laser output is directed over the laser light path to count the blades and to strobe the laser on the desired blade.

Abstract: Index of refraction measurements are made by means of an optical device in which a coherent light beam is divided into an object beam and a reference beam, each of which is directed through a separate path in a common light transmitting medium. The object beam is also transmitted en route through a test volume that accommodates a substance to be tested. It is subsequently recombined with the reference beam to form a single output beam. The output beam is received by a photo detector and its intensity is measured. The intensity of the detected output beam is related to any phase shift between the object and reference beams. The phase shift in turn is a measure of the index of refraction of the test substance. Information relating to density, temperature and pressure of the test substance can be derived from measured index of refraction values by using conventional conversion formulas.

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: Increased bandwidth, reduced axial ratios and improved beam shape and sidelobe characteristics are achieved with non-uniform diameter helical antennas. The antenna structures are configured to various combinations of tapered diameter and uniform sections. By varying the number of turns, diameters of the helix sections and lengths of the various helix sections, antennas are synthesized to yield specific gain-frequency response characteristics.

Abstract: Sidelobe suppression and other beam transmission property manipulations in directional beam forming antennas is accomplished by means of a spatial filter. The filter geometry consists of a plurality of metallic gratings separated by air or other low dielectric constant dielectric substance. The filter is placed directly over the antenna radiating aperture and is encompassed by a tunnel structure of electromagnetic wave energy absorbing material. The shunt susceptance characteristics of the metallic gratings together with the integrating spacing distances are synthesized in a manner that effects full transmission of beam power in a selected beam direction while offering substantial rejection of it in other directions.

Abstract: A tracking radar error signal that is independent of pulse to pulse variations of amplitude of the received signal is derived by combining separately detected sum signal energy and difference signal energy in a manner that provides composite error signal pulses that are one-half sum signal energy and one-half sum plus difference signal energy. The pulse composition is realized by means of an RF switch that interrupts the difference signal during approximately one-half of each pulse period. The composite error signal is detected by an IF logarithmic detector and subsequently processed by two parallel box car generators. One box car generator is gated to process sum signal energy and the other is gated to process sum plus difference signal energy. The tracking error signal is obtained from a single pulse by feeding the outputs of the two box car generators to a differential amplifier and obtaining the difference voltage at its output.

Abstract: A waveguide lens having improved efficiency and bandwidth characteristics is realized by appropriately combining the waveguide element array configuration of a conventional zoned waveguide lens with the phase shifting means of a constant thickness variable phase shift type waveguide lens. The length of each waveguide element and the phase shift required of its phase shifting means are functions of the waveguide elements radial distance from the lens axis. Design equations for determining waveguide element length and phase shift values are developed using both single and double frequency design procedures.

Abstract: Passband distortion due to mass loading in withdrawal weighted surface acoustic wave transducers is substantially reduced by a thinning technique in which interdigital transducer electrodes are selectively withdrawn to synthesize a response function H.sub.o '(N). H.sub.o '(N) is a modified response function that has been scaled from a desired response function H.sub.o (N) by a thinning factor THIN. THIN is a positive, non-zero constant with a maximum value of unity. Thinned withdrawal weighted transducers fabricated in accordance with the technique have electrode weights that are normalized to less than unity and achieve mass loading reduction with a minimum amount of degradation of the desired response function.