Abstract: The self-synchronization circuit splits the incoming signal into two circuit paths where the signals are frequency shifted by a frequency signal equal to the carrier frequency so as to provide an in-phase signal in one circuit path and a quadrature signal in the other circuit path. The frequency shifting circuit includes at least a controllable oscillator. The output of a first multiplier which multiplies the in-phase and quadrature signals, is fed to a clock recovery circuit which determines the clock frequency. A second multiplier multiplies the output of the first multiplier with the clock recovery circuit output to provide a signal which controls the controllable oscillator. In addition, a frequency discriminator utilizes the in-phase and quadrature signals to initially coarse control the controllable oscillator frequency.

Abstract: The thinned arrayed transducer for a sonar system includes an array of sonar elements mounted in rows (layers) and columns (staves) on a structure, preferably cylindrical, to form a checkerboard pattern wherein the spacing between adjacent elements in the rows and the columns is equal to or greater than .lambda..sub.m /2, where .lambda..sub.m is the wavelength of the signal of frequency f.sub.o transmitted in the medium where the sonar is being used. The transducer structure is made from a layered cloth impregnated with a phenol based material, and includes openings in which the sonar elments are mounted. The sonar elements which are effectively a half wavelength in length consist of a cylindrical ceramic section fixed end-to-end to a cylindrical metal section. The metal section is made of a loading metal, such as brass. The transmit-receive circuitry energizes the elements by row using a modulated signal to form a variable sonar beam.

Abstract: The inverter may be single phase with one inverter leg or N-phase with N inverter legs for connection across a DC source. Each leg includes a pair of series connected thyristors with a terminal between the thyristors for connection to a load. In addition, each thyristor has a diode connected in reverse polarity across it. A commutation circuit which includes an inductor in series with the inverter legs and a capacitor in parallel with the inductor and the inverter legs, provides a commutation pulse to turn off the thyristors in each leg. A further isolating inductor is connected at the DC power input to the inverter, and a reverse polarity feedback diode may be connected across it.

Abstract: The timed AC switch comprises a manual on-off switch in series with bidirectional semiconductor switch, such as a triac, for connection in a loop with an AC source and a load which would generally be incandescent or fluorescent lamps. The semiconductor switch is driven by an RC oscillator which is under the control of an inhibit circuit and a digital counter which itself is driven by the oscillator. The counter is reset at initial start up, and may also be reset while operating or after counting out. The times switch may also be controlled to inhibit the oscillator for a very short time as a warning before finally timing out.

Abstract: The optoelectronic switch includes a photosensitive GaAs FET onto which an optical signal may be directed. The optical signal is derived from an RF modulated light source. A voltage circuit is connected to the FET to switch the FET "on" or "off" by placing a positive or zero voltage respectively on the drain. An isolation of over 70 dB is obtained in this FET switch.

Abstract: The separator charges the particles to be separated and passes them through an alternating electric field which has a non-uniform intensity in a direction perpendicular to the forward direction, and which also has field lines curved in the same direction. The particles which move along the curved field lines due to their charge are thus subjected to a centrifugal force which effects their separation. The separator includes a pair of conductive electrodes, the first being substantially horizontal or possibly at an angle from the horizontal and the second mounted facing the first at a predetermined angle to it. The electrodes may be planar or curved. The field is supplied by an ac source operating in the range of 3 to 1000 hz. A mechanical vibrator attached to the first electrode imparts the forward motion to the particles.

Abstract: The jitter determining apparatus uses only a jittery clock signal of period T.sub.b recovered from the received data signal to determine peak to peak jitter J.sub.pp and jitter distribution. The apparatus includes an AND gate having a pair of inputs. The inputs are coupled to a first signal which is the jittery clock signal delayed by a fixed amount nT.sub.b where n is preferably greater than 5, and to a second signal which is a jittery pulse signal generated from the jittery clock signal. The second signal is also controllably delayed by a factor greater than twice the jitter J.sub.pp. The AND gate produces output pulses when coincidence occurs between the two signals as the delay of the second signal is selectively varied. A counter counts the pulses for each selected delay position and thus provides the peak to peak time jitter J.sub.pp of the clock signal.

Abstract: The multilevel inverter includes a voltage divider which when connected across a dc source E.sub.D, provides voltage at terminals having values between +E.sub.D to -E.sub.D. A first and a second set of thyristors pairs are connected between the positive or negative terminals, respectively, and a load terminal for applying selected voltage levels to the load. Any thyristor pair in these sets may be turned-off by firing the thyristor pair at the next highest voltage level. However, the main thyristors which are connected to the +E.sub.D or -E.sub.D terminal is turned-off by a commutation circuit. This circuit includes a single capacitor maintained at zero voltage and subjected to an oscillating voltage during the commutation cycle to turn-off the conducting main thyristor. Such an inverter can easily provide a waveform having a series of pulses at one or more voltage levels thereby eliminating harmonics in the output.

Abstract: The method and apparatus provides the in-phase I and quadrature Q components of a bandpass signal x(t) of center frequency f.sub.c and bandwidth 2w. The signal x(t) is heterodyned to have an intermediate center frequency f.sub.o where w.ltoreq.f.sub.o .ltoreq.f.sub.c. This signal is divided into two signals and each is sampled during successive periods T.sub.s where T.sub.s =m/f.sub.o and m is an integer. However, the instant of sampling of one signal is shifted with respect to the other by b/4f.sub.o where b is an odd integer. In the various implementations, the shift may be either positive, negative, or both, to provide the quadrature component Q, whereas the sampling of the other signal provides the in-phase component I.

Abstract: A rare-gas hydrogen-halide laser is improved by including or adding a predetermined quantity of a hydrogen donor additive to its gas mixture. The closed-off operation lifetime of lasers such as XeCl, KrCl, or XeBr are tripled by adding up to 0.05% hydrogen to the laser gas mixture.

Abstract: The terminals in a distributed multi-port communications system are connected by a common communication channel such as found on a broadcast coaxial cable. The terminals communicate with one another during sequential poll cycles to fulfill low data rate requirements or during a burst cycle to fulfill high data rate requirements. Each poll cycle includes a number of time slots with at least one time slot assigned to each terminal during which it can transmit data to any other terminal or request for a burst cycle. The burst cycles are allotted to requesting terminals in accordance with a predetermined priority. During the burst cycle, whose length varies in time with respect to the poll cycle, data are transmitted at a high data rate.

Abstract: The microwave heating apparatus consists of a microwave cavity, a energizing source, a mechanism for holding and agitating a load, and a temperature detector for continuously monitoring the temperature of the load. It is particularly useful for heating and quickly thawing frozen blood plasma or intravenous admixtures as needed. These must be thawed uniformly and to some preselected temperature so as not to destroy their effectiveness. It also helps to prevent wastage of the blood plasma thawed in anticipation of an emergency.

Abstract: The apparatus generates two optical beams which are directed to a relatively moving solid surface where an interference pattern, having substantially parallel fringes, is formed. The light is scattered and thereby modulated by irregularities on the surface. This modulated light is received and the signal is processed to indicate the length of the surface or its relative speed. The signal processor converts the modulated light signal to a pulse train, and adds pulses to the pulse train when a drop-out in the signal is detected, i.e. when the time between pulses in the pulse train is greater than a factor times the average period of the pulse train. The corrected pulse train is a function of the length of the surface or the relative motion between the apparatus and the surface.

Abstract: The low-loss reflection star coupler has a bundle of multimode optical fibers which is folded on itself and fused over a predetermined length to form a bundle loop. During the fusion process, the fibers are elongated into biconical tapers in the fused section. A hybrid transmission-reflection star includes one or more further fibers having only one biconical tapered section which is fused to the fused section of the fiber bundle.

Abstract: The ac current comparator bridge measures the resistance of an unknown resistor at 50-60 Hz with an accuracy in the order of 10 parts per million. The current in the unknown resistor is compared, using a current comparator, to the current in a reference resistor for the in-phase component, and to the current in a reference capacitor for the quadrature component or phase defect. Once an ampere-turn balance is achieved in the comparator by adjusting the winding turns, the unknown resistor's values are a function of the reference resistor, the reference capacitor, the voltage sources driving the currents through the unknown resistor and the references, as well as the turns of the windings.

Abstract: A method and apparatus is described for reducing the gas consumption rate by controlling the gas composition in a repetitively pulsed high pressure and/or high energy density TE CO.sub.2 laser. Detrimental gas species formed in the discharge are removed by chemical reaction in the gas phase and the reaction products are removed by a trap in a recirculator loop. In particular, the primary detrimental species is oxygen, the reducing gas added to remove this is hydrogen or deuterium and the resulting oxides of hydrogen or deuterium are removed by a molecular sieve.

Abstract: The digital oscillator includes a memory which stores 12 bit words representing sampling points of the analog waveform to be produced and a D/A multiplying converter which receives the bit words and converts them to an analog values, the amplitudes of which are controlled by a reference voltage. The analog output is monitored and compared to a stable reference source in order to generate the controlling reference voltage thus maintaining a constant amplitude digital oscillator output.

Abstract: The multi-filar moving coil loudspeaker includes a magnetic field structure which provides a unidirectional magnetic flux across an air gap, an acoustic diaphragm, and a coil set positioned in the air gap and connected to the diaphragm. The coil set has a plurality of insulated coils wherein the coils have approximately the same resistance and inductance and cut substantially the same flux lines in the air gap. The coil set has two or more wires which are twisted around one another and then wound about a coil form. The coils in the coil set may be connected in series or parallel aiding, or in series bucking pairs. In a loudspeaker circuit, the coils are connected into two groups, each having one or more coils. The first group is connected to input terminals, and the second group is connected to a feedback amplifier having an output connected to the first group of coils.

Abstract: This reference source provides a current which is of relatively high magnitude and which leads the voltage by substantially 90.degree.. It includes a reference capacitor which is highly stable and pure but of low capacitance, and a power capacitor which has a high capacitance. The capacitors are connected together at one end for coupling to a voltage source. A current comparator compares the currents flowing through the reference capacitor and the power capacitor, and provides a difference signal. A circuit generates a current in response to the difference signal and adds the generated current to the current through the power capacitor resulting in a current having a waveform and phase substantially identical to the reference capacitor current which leads the voltage source voltage by substantially 90.degree..

Abstract: The low loss access coupler includes two multimode optic fibers, each having a biconical taper section. The biconical taper sections of the fibers are fused together to provide optical coupling between the fibers. The fused fibers may also be twisted around one another to enhance mode mixing. The access couplers may be produced by fusing two fibers together along a small length, then heating the fused length and pulling the fibers to form the biconical tapers; or by twisting a portion of each of the fibers around one another, applying a tensile force to the twisted portions of the fibers and heating a region of the twisted fibers to soften and fuse a predetermined length of twisted fibers. If the fibers already have biconical taper sections, the access coupler may be produced by twisting the fibers together along their taper sections and heating a region of the taper sections to fuse them together.