Abstract: The signal processing apparatus described is particularly useful in a graphic arts process simulating system. In a preferred embodiment, the apparatus makes use of a vidicon to generate a video signal in response to light signals. A controlled iris adjusts the intensity of light signals into the vidicon in accordance with the peak value of the video signal, so that the vidicon can operate with a range of light intensities corresponding to its optimum dynamic range. Prior to the iris adjustment, a measurement of the average video signal level is made and the resulting value stored. The stored signal value is used in conjunction with the average video signal level after iris adjustment to generate a pedestal correction voltage, which is used in a clamping circuit to provide an output video signal which is representative of the true characteristics of the image.

Abstract: An antenna system having an array of radiating elements arranged in element modules is provided with coupling networks, one associated with each element module, each network having an input port. Each coupling network provides coupling between its input port and elements in the associated element module, as well as independent coupling between its input port and selected elements associated with other modules in the array.

Abstract: In any array antenna system having a coupling network interconnecting a plurality of element groups, the coupling network is provided with phase adjustments to shift the angular location of the effective element radiation pattern. An effective technique for this phase adjustment in a microstrip coupling network makes use of a field altering structure positioned adjacent the microstrip.

Abstract: In a doppler radionavigation system wherein a transmitted signal has opposite frequency coding during alternating time intervals, a reference antenna is provided which has different radiation modes during the alternating time intervals. In a preferred embodiment, the two reference antenna modes have substantially the same amplitude radiation pattern, but different phase radiation characteristics. The phase between the radiation in a selected direction and the radiation in the remaining directions is different for the two antenna modes. This phase change substantially reduces the position determination error resulting from multipath signals.

Abstract: Disclosed is a multiterminal acoustic surface wave transducer which has a unidirectional response characteristic over a selected operating frequency band and is capable of launching and receiving surface waves in a body of piezoelectric material. In a specific embodiment the transducer includes a plurality of sets of first, second and third parallel electrodes arranged in cascade on a surface of the piezoelectric material with a center-to-center electrode spacing equal to one-third wavelength of a selected frequency within the frequency band. Corresponding electrodes in each set are interconnected, with each group of interconnected electrodes forming a terminal of what is in this case a three terminal transducer. When a three phase electrical signal is supplied to the terminals of the transducer with a 120.degree. phase separation between terminals, the transducer will launch a corresponding surface wave in the piezoelectric material in the direction of phase progression among the electrodes.

Abstract: A processing apparatus for determining the frequency of a supplied signal is usable in a Doppler microwave landing system. The apparatus derives scalar signals representative of signal frequency and amplitude and computes the average value of the scalar signals over a number of time intervals prior to dividing the signals to produce an output signal representative of average supplied signal frequency.

Abstract: Disclosed are array antenna systems wherein the effective element pattern is modified by means of coupling circuits to closely conform to the ideal element pattern required for radiating the antenna beam within a selected angular region of space. Use of the coupling circuits in the embodiment of a scanning beam antenna significantly reduces the number of phase shifters required as compared to prior art array antennas.

Abstract: Disclosed is a method for fabricating an acoustic surface wave device having reduced temperature coefficient of propagation delay within a desired range of operating temperatures. In one embodiment the device includes a piezoelectric substrate comprising X-propagating Y-cut quartz having a cut angle at which point of zero temperature coefficient of propagation delay is at a temperature which is higher than the desired range of operating temperatures. There is included on the substrate in the desired path of the propagating surface wave a deposit of conductive material which has the effect of lowering the temperature at which the point of zero temperature coefficient of propagation delay occurs, thereby reducing the magnitude of the temperature coefficient of propagation delay within the desired range of operating temperatures.

Abstract: Disclosed is an acoustic surface wave device having reduced temperature coefficient of propagation delay within a desired range of operating temperatures. In one embodiment the device includes a piezoelectric substrate comprising X-propagating Y-cut quartz having a cut angle at which point of zero temperature coefficient of propagation delay is at a temperature which is higher than the desired range of operating temperatures. There is included on the substrate in the desired path of the propagating surface wave a deposit of conductive material which has the effect of lowering the temperature at which the point of zero temperature coefficient of propagation delay occurs, thereby reducing the magnitude of the temperature coefficient of propagation delay within the desired range of operating temperatures.

Abstract: Disclosed is an acoustic surface wave device having surface wave transducers coupled to a piezoelectric substrate by harmonic coupling. In one embodiment the device has two transducers, each having a different selected fundamental periodicity and harmonic piezoelectric coupling in a selected range of operating frequencies.

Abstract: Disclosed is a system for receiving a signal from a known direction and rejecting interfering signals arriving from other directions. The system makes use of an antenna unit having multiple output ports, each responsive to signals from a different selected region of space. The output port correspondong to the region of space, which includes the direction of the desired signal, is coupled directly to an output combiner while the antenna ports corresponding to the remaining regions of space are combined to form a reference signal. Means are provided to form a correction signal in response to the reference signal and output signal for suppressing interfering signals arriving from other than the selected region of space.

Abstract: Disclosed is a system for receiving a signal from a known direction and rejecting interfering signals arriving from other directions. The system makes use of a multibeam antenna having multiple ports corresponding to the multiple beams. The port corresponding to the beam in the direction of the desired signal is connected directly to a receiver while the outputs of the remaining antenna ports are used to cancel interfering signals arriving on their corresponding beams.

Abstract: Disclosed is an adaptive filter for suppressing interfering narrow-band signals in a composite signal containing a desired broad-band signal. The adaptive filter is useful in a system which uses a broad-band signal and signal processing apparatus to derive information from the broad-band signal. In one embodiment the system makes use of a delay line to provide a delayed replica of the composite signal which is used to provide a correction signal to cancel the interfering narrow-band signal. The desired broad-band signal is not canceled by the adaptive filter.