Abstract: A dual I.L.S. glide slope system for allowing a normal 3.degree. descent path plus an additional 6.degree. descent path which can be used for noise abatement procedures etc. In accordance with the present invention these glide slopes are provided on a single assigned R.F. channel with no inverted courses interposed. The first signal null will occur at 9.degree. elevation when all signals will be zero, producing a "flag" alarm.

Abstract: The improved radiometric target seeking system incorporates automatic gain control features including phase tracking automatic gain and automatic gain scan amplitude controls in a system which is basically a dual-axis, gimballed, conical-scan radiometric sensor designed to operate in either active or passive modes and to provide angular line-of-sight rate steering signals to guidance control apparatus. Target-derived automatic gain control signals permit separation of desired stationary target signals from significant background clutter, and a unique adaptive processor minimizes degradation of tracking response and accuracy.

Abstract: The position of a receiver responsive to C/A signals derived from multiple, orbiting space crafts is determined to an accuracy of greater than 300 meters. Each of the C/A signals has the same carrier frequency and a different, predetermined Gold code sequence that normally prevents position determination to be more accurate than to within 300 meters. C/A signals transmitted to the receiver are separately detected by cross correlating received Gold code sequences with plural locally derived Gold code sequences. Four of the detected C/A signals are combined to compute receiver position to an accuracy of 300 meters. To determine receiver position to greater accuracy than 300 meters, the relative phase of internally derived Gold code sequences is varied over the interval of one chip of each sequence, to derive second cross correlation values indicative of received and locally derived Gold code sequences; the second cross correlation values represent different positions within the computed 300 meter position.

Abstract: 2. A doppler shift rate detector system comprising: a first mixer; input ns for simultaneously applying a carrier signal and a doppler shifted sideband signal to said first mixer; first and second intermediate frequency amplifiers coupled to said first mixer; a mixer and an intermediate frequency amplifier stage coupled to said first and second intermediate frequency amplifiers; a mixer and oscillator stage coupled to said mixer and intermediate frequency amplifier stage; a frequency multiplier coupled to said mixer and oscillator stage; a second mixer coupled to said frequency multiplier; a delay line having an input coupled to said frequency multiplier and an output coupled to said second mixer, a narrow-band active filter coupled to said second mixer; an indicating means coupled to said filter; a low frequency switch coupled to said filter; a R. F. switch coupled to said first and second intermediate amplifiers; a sweep generator coupled to said R. F.

Abstract: A bearing detection system used in an Airborne Collision Avoidance System. The detection end of the system is formed as a directional antenna having 3 directional antenna elements extending radially at a 120.degree. angle with each other. The antenna element has an actual length corresponding to .lambda./8, wherein .lambda. is the wavelength of the receiving wave, but the element has an effective length corresponding to .lambda./4 by the provision of an impedance matching plate and a back lobe suppression plate. Bearings of the incoming wave can be detected by means of relative strength of the receiving signal levels of the three antenna elements obtained by amplitude comparison and by forming 3 bit truth table for six directions including the 3 directions of the antenna and 3 boundary directions thereof by the strength of the receiving signal received by the three antenna elements.

Abstract: A beamformer for wideband signals wherein the elemental signals available the sensors of a receiving array are subjected to Fast Fourier Transformations which decompose them into a plurality of narrowband signals. The narrowband signals, which consist of signals having the same Fourier coefficients, are subjected to appropriate phase shifts to form a plurality of narrowband beams having the directional characteristics desired. Reconstruction of the wideband signal is accomplished by subjecting the narrowband beams to an inverse Fast Fourier Transform. The beamforming is thus performed with narrowband signals, and only phase shift circuits are required.

Abstract: A circuit for the comparative vector measurement of keyed radio signal pulses, in particular DME pulses which arrive virtually simultaneously in a plurality of receivers and which can exhibit large level differences is utilized where, in each receiver, the pulses are fed to a switching amplifier which has an amplification which is adjustable in discrete stages and the reduction of which is effected automatically with the rise in the leading edge of the relevant signal pulse, and where, when the relevant switching amplifier of the receivers has been traversed, at a specific measuring time which is common to all receivers, the instantaneous amplitudes and instantaneous phases of the measuring signals are measured, the circuit providing that the pulses are fed to the switching amplifier by way of a delay device and, that for the setting of the amplification of the switching amplifier, a control circuit is provided which is directly fed with the radio pulses and which comprises a logarithmic amplifier and a subse

Abstract: A pulse repetition frequency (PRF) detection system is provided for indicating the existence of pulse trains having predetermined repetition frequencies in a composite signal containing pulse trains of different pulse repetition frequencies. The system includes a plurality of independent sorters to which the composite signal is sequentially applied. Each of the sorters is operable to detect a pulse train having a predetermined pulse repetition frequency, to indicate the detection, and to produce pulses for inhibiting or blocking the application of the corresponding pulses of the composite signal on a pulse-by-pulse basis. The sorters may be arranged and interconnected in a decreasing order of frequency detection whereby the signal applied to each successive sorter has all higher frequency detected pulse trains removed therefrom.

Abstract: A radio frequency signal direction finding system wherein radio frequency signals received at output ports of a multibeam array antenna are sequentially sampled, in response to a sampling signal, at a frequency f.sub.s. The sampled signals are fed to a receiver channel which is tuned to the sampling frequency to produce a composite signal having a frequency f.sub.s and a phase angle, relative to a reference phase angle of the sampling signal, which provides an indication of the relative signal levels received at the output ports and hence an indication of the angular direction of a source of the radio frequency signals.

Abstract: A trans-horizon navigation system wherein a predetermined sequence of control pulses is phase-encoded onto an RF carrier for transmission from a first transceiver to a second transceiver, the second transceiver including a correlator which provides an output pulse in response to detecting the sequence of control pulses in a received transmission. An improved AGC circuit configuration is also disclosed.

Abstract: The antenna arrangement for radar or direction finding purposes, respectively, has sum and difference patterns for mono-pulse operation comprising a reflector and at least two linearly polarized exciters located approximately in the center between which perpendicular to their polarization direction a metallic conductive plane partition is disposed which extends to the reflector and stands perpendicularly thereon, wherein the partition does not extend through the entire reflector from edge to edge but is arranged only approximately in the area of the exciters.

Abstract: A VHF radio frequency antenna for a homing receiver suited for airborne aications and comprising a pair of right angled antenna elements of like configuration terminating in a common non-conductive joint of insulator material while their opposite ends terminate in dielectric supports mounted on an electrically conductive ground plane such as an aircraft skin. The ends of the elements terminating in the dielectric supports additionally connect to signal coupling means which feed to a homing receiver or other utilization device through equal length transmission lines.

Abstract: A target seeker circuit contained in a projectile having a trajectory guidance mechanism cross-correlates returns of a cross-polarized antenna pattern to distinguish between target returns reflected by man-made targets and clutter returns reflected by naturally occurring articles to cause the trajectory guidance mechanism to direct the projectile towards the target. One coordinate of diversity in the cross-polarized returns is achieved by changing the RF frequency of the antenna pattern while a second coordinate of diversity is achieved by changing the aspect range of the clutter. The target returns are distinguished from the clutter returns either by comparison to a threshold value which is set in relation to the worst case clutter level or, alternatively, by comparison to an adaptive threshold which is responsive to the dynamic clutter level.

Abstract: Monitor comprises approximately matched means for sampling currents in the radiating elements. The sample currents are divided into three sets of parts. One set is used for monitoring course position, another set for monitoring course width and the third set is used to monitor magnitudes of the currents in the radiating elements. The interference by the samples in the first and second sets with the monitoring of magnitudes is greatly reduced by selecting path lengths used in the course position and course width monitoring systems so that the interfering effect of the samples in the first and second sets nearly cancel each other. The magnitudes of the currents in the third set are compared with preset standards.

Abstract: A system for forming a beam of radiant energy which is incident upon or radiated from an array of radiating elements such as sonar transducers. As a wavefront progresses across the array, samples of signals received by individual ones of the transducers are selected in accordance with specific beams to be formed, the selected samples being summed together through a sequence of partial summations until a complete summation of a sample of a beam is obtained. The sequence of partial summations is initiated successively for each output sampling interval. For a long array, wherein the transit time of a wavefront across the array is longer than the intersample interval, a plurality of the sequences are generated concurrently. All partial sums for all beam samples are generated periodically at the output sampling rate and are stored in a memory.

Abstract: A receiving system for a time-reference, scanning beam radio guidance system in which the scanning beam, an offset frequency reference signal and a time reference signal are provided from the ground beacon location. The receiving system includes a first detector responsive to the scanning beam and offset reference signals to provide a spectrum centered about the offset signal. A bandpass filter with sloping skirts on both sides of the center (offset) frequency provides tapering, with decreasing amplitude response on each side of the center frequency, the width of the spectrum being a function of the aperture of the beam transmitting antenna at the ground beacon. Angular information is determined by thresholding the beam signal to find two points on either side of beam center, averaging these times and comparing with the time-reference signal to air-derive angular navigational data, especially for aircraft landing approach systems.

Abstract: A frequency-modulated continuous wave (FM-CW) ranging system includes apparatus which utilizes a target simulating delay line and scaling device to compensate for undesired changes of the FM modulation waveform.

Abstract: An apparatus or method, for characterizing carrier waves according to the direction in which the carrier waves are transmitted or received, comprises radiating or receiving from a position which is moved repetitively along a line of motion having a predetermined, fixed location in a frame of reference. The radiating or receiving position may be moved so that at least one of the speed and direction of motion is abruptly changed. The radiating or receiving position may be moved back and forth along two non-parallel, straight lines of motion, whereby elevational and aximuthal angles of propagation are determinable solely responsively to the amplitude of the frequency shift induced by the changes in direction of the motion along the lines of motion.

Abstract: A relay system for relaying hyperbolic navigation signal information received at a mobile. The mobile has a simple relay transmitter and receives signals which are radiated from different navigation transmitters in turn on a single frequency f.sub.rf. The received signals are heterodyned to a single audio frequency f by mixing with a locally-generated or transmitted signal f.sub.o. Phase errors are minimized by transmitting the information as phase changes of the single frequency f signal in a single transmission channel.

Abstract: A VOR monitoring system responds to the phase difference between two signals to determine the bearing of an aircraft with reference to a transmitting station. Even harmonic distortion interference in the monitored signals produces a bearing error and when the bearing error exceeds a preset limit the monitor of the present invention energizes an alarm. The two monitored signals are identified as a 30 Hz reference and 30 Hz variable signal, each of which is doubled in frequency to 60 Hz and divided by three to produce two 20 Hz signals. One of the 20 Hz signals is identified as a positive error signal and the second as a negative error signal. The negative error signal is phase delayed through a programmable delay by an amount related to the bearing of an aircraft with respect to a transmitting field station. The two error signals are then phase compared and the difference tested against a preset bearing error limit.