Abstract: A method for determining a filter that is very selective and having linear phase is described. The method starts with choosing a pole constellation in the complex frequency plane in a unique manner so that a desired passband phase of the filter is linear while preserving the desired magnitude. The method seeks to design filters that have ideal responses in both gain and phase or gain and time. This process is done methodically by finding locations of poles that yield sensible compromises between the extremes. It also makes full use of well-known traditional characteristics of the filters at the extremes.

Abstract: A crystal oscillator having a crystal filter with multiple crystals in a ladder configuration, resonant at a desired operating frequency. An oscillatory signal loop feedback path includes a voltage controlled phase shifter operable to shift the phase of the signal in the feedback loop in response to an applied control voltage. The feedback loop also includes a loop phase shift circuit to ensure that the feedback signal is a multiple of 360°, and a band pass mode selection circuit for eliminating unwanted frequencies.

Abstract: A liquid cooling system contained completely on a circuit board assembly. The liquid cooling system uses microchannels etched within the circuit board, those microchannels being filled with electrically conductive fluid that is pumped by a non-mechanical, magnetic pump. The pump can be separate from the device on the circuit board which is to be cooled or it can be integrated with the device that is to be cooled. In the latter circumstance, the same current which flows through the electronic device is the current which generates the Lorentz force that pumps the electrically conductive fluid through the microchannel.

Abstract: An acoustic resonator filter having at least one of electronically variable center frequency and bandwidth has a shunt coupling consisting of an inductor and voltage variable capacitor matrix. A pair of acoustic resonators each having a parallel inductor are connected to each other and to the shunt coupling network. One of a pair of voltage variable capacitor matrixes each having a center frequency command input voltage is connected to each acoustic resonator and an associated inductor. This circuit can be extended to provide more selectivity and attenuation.

Abstract: A miniature thin film microwave frequency acoustic filter device comprising acoustic resonators formed on the same dielectric membrane so that their frequency responses are identical. Because the filters are miniature, they can be manifolded without manifolding circuitry that normally causes significant filter losses.

Abstract: A unitary surface acoustic wave device for continuous quadraphase coding of a high amplitude video impulse with provisions for controlling the rise and fall times of such impulse.

Abstract: An ultra low noise oscillator circuit including a crystal and having two outputs. At the two outputs, the signal is correlated and the noise outside of the crystal bandwidth is decorrelated. Summing the two outputs in a hybrid circuit significantly reduces oscillator phase noise by almost 3 dB. In addition, these outputs can be used to perform a single oscillator noise test on the oscillator or crystal.

Abstract: A jamming analysis and transmission selection system for a radar wherein the frequencies present in the environment are sampled during a discrete time interval following each radar transmission; and utilizes a surface acoustic wave device having a plurality of spaced groups of interdigitated fingers on a substrate wherein each of said groups has a finger width and spacing to be resonant at each of a plurality of anticipated different interfering frequencies. The output of the device is sampled following each discrete time interval to identify the presence of the selected interfering frequencies to change the transmission frequency of the radar transmitter to a non-interfering frequency.

Abstract: A surface wave phase correlator comprises a pair of substantially identical launch and receiving filter electrode patterns disposed on a common piezoelectric substrate. The correlator is employed with receiving and processing circuitry in a monopulse radar system to provide relative phase information for target calculations by a digital processor. Fast rise and fall times for the correlator output signals enable rapid digital processing of incoming target signals.

Abstract: A filter array is provided for extracting velocity information from the return pulse of a Doppler radar system. The array consists of a plurality of two-pole, bandpass crystal filter networks directly connected in parallel, the filter networks including crystal resonators and all but one of the networks having reactances in series with the resonators. The crystal resonators are identical in all of the networks and the reactances change progressively in successive networks in such a manner that adjacent filter networks respond to contiguous frequency bands.

Abstract: A crystal resonator is disclosed of a single crystal of the approximate composition Tl.sub.3 BX.sub.4 having two parallel surfaces normal to a zero temperature coefficient of frequency direction and having an electrode mounted on each surface, where B is vanadium, niobium, or tantalum, and X is sulfur or selenium. A filter is disclosed of a crystal resonator coupled to a capacitor or more than one crystal resonator in series each coupled to a capacitor. A voltage controlled crystal oscillator resonator is disclosed of a crystal resonator in parallel with an inductor and a varactor.