Abstract: The annular energy distribution in the output beam of a laser having an unstable resonator is evenly distributed across the entire beam profile by a synthesizer comprising a pair of mirrors adjacent to the output end of the resonator and operative on the output beam to redirect part of the beam from the annular outer portion to the energy-vacant central portion. One of the pair of mirrors is partially optically transmissive and concavely shaped and is disposed to reflect and converge part of the outer beam portion toward the other mirror and to transmit the balance. The other mirror is highly reflective and convexly shaped and is disposed to redirect and collimate the reflected beam part within the central portion toward the concave mirror parallel to the outer beam portion.

Abstract: A data rate converter for use in telecommunications inserts supervisory bits into a data stream to increase the data rate, in one application, from 56 kbps to a standard 64 kbps. A standard 64 kbps PCM telephone channel uses 8-bit words for transmission, whereas 56 kbps occupies only 7 bits of an 8 bit word in such a telephone channel. Supervisory bits are inserted at the exact time when the data channel clock signal and the transmission line clock signal are in phase alignment.

Abstract: A signal detection circuit having a balanced modem is described. A switching circuit responsive to a selected linear input signal provides a square wave having the same frequency as the linear input signal. The modem, using a DC bias provided from the square-wave signal, is responsive to the square wave and linear input signals for providing a DC output having a magnitude proportional to the magnitude of the selected linear input signal.

Abstract: Apparatus for continuously making an electret tape having an electrically conductive strip with dielectric layers on opposite sides thereof in which the tape is moved vertically in the direction of its length. A pair of opposed electrodes connected to a high voltage source and continuously wetted with a dielectric fluid contact the respective dielectric layers to electrostatically charge each layer. A second pair of identical electrodes connected to the high voltage source and the dielectric fluid supply is spaced above the other electrode pair and repeats electrostatic charging of the dielectric layers to insure uniformity of charge thereon. Fluid on the layers is dried by air blown against them as the tape emerges from the second electrode pair.

Abstract: Apparatus for making an electret tape having an electrically conductive strip with a dielectric layer on one side thereof comprises tape supply and take-up reels arranged to move the tape from the former to the latter in an upwardly inclined plane and an electrostatic charging assembly between the reels having a dielectric fluid applicator for applying the fluid directly to the dielectric layer, a sponge-like electrode connected to a high dc voltage source, and an air blower for drying the fluid on the tape. The electrode is longitudinally spaced from the fluid application point in the direction of tape movement, engages the dielectric layer across its full width, and is wetted on the tape input side by the fluid on the layer. The blower is on the tape output side of the electrode with a baffle spaced closely to the dielectric layer between the blower and the electrode.

Abstract: In a mobile radiotelephone system, N separate modulated carrier signals in N frequency channels are applied to a demodulating radio receiver which provides a succession of N different output signals each having idle and busy states. An idle and signal-to-noise detector monitors each of the output signals of the radio receiver. The detector provides a first logic signal when one of the output signals concurrently exhibits an idle state and has at least a predetermined minimum signal-to-noise level, and provides a second logic signal at all other times. A receiver switching circuit, in response to the second logic signal, causes the receiver to cyclically switch to each of the N frequency channels. When the receiver switches to a carrier signal which causes the detector to produce a first logic signal, the switching circuit causes the receiver to lock onto that particular carrier signal.

Abstract: When connected to a source of unregulated DC power, a series switching regulator delivers a constant output current to a load. A series switch, in response to a control signal, adjusts the flow of input power by switching ON and OFF. The switching operation generates a gated power signal having a variable duty cycle, and the duty cycle depends on the power demands of the load. During the period when the switch is ON, the energy in the gated power signal is stored in the magnetic field of a transformer. During the period when the switch is OFF, the transformer releases the stored energy to capacitive storage devices and to the output load. The capacitive storage devices also supply current to the load when the transformer is storing energy. Feedback signals from voltage and current sensors combine to form a single control signal which adjusts the duty cycle of the switch until the power demands of the load are met.

Abstract: A novel technique for coupling microwave signals to a slot transmission line and for effecting a simultaneous impedance transformation. One lead of a microwave capacitor, connects to a source of microwave signals via a microstrip or coplanar transmission line. The other capacitor lead, located in the same plane as the slot line, crosses the slot line at a right angle and connects to the ground plane on the other side of the slot. A short-circuited segment of the slot line extends N.lambda./4 beyond the point of crossing where N is an odd integer.

Abstract: A microwave signal generator having improved noise spectral characteristics employs a plurality of amplifier-frequency multiplier circuits in combination with a very stable VHF oscillator. Instead of lumping the amplification and frequency multiplication together, each in a single stage, a plurality of amplifiers and multipliers are interleaved, as described herein, resulting in reduced FM noise generation.

Abstract: A DTMF generator includes a high gain differential amplifier having a noninverting input, an inverting input, and an output. A first audio oscillator connects to the inverting input of the amplifier via a first series of frequency determining components. A second audio oscillator connects to the amplifier output via a second series of frequency determining components. The noninverting input of the amplifier connects to ground. A plurality of SPST switches interconnects the first and second frequency determining components, such that when any particular switch is closed, a unique feedback path is established from the amplifier output to the inverting input. This causes a ground potential to exist at the contacts of the particular closed switch thereby forcing both oscillators to turn on.

Abstract: The disclosed voltage regulator circuit provides a regulated direct output voltage, across first and second output terminals, when an unregulated direct input voltage is applied across first and second input terminals. The second terminals are common to both input and output connections. A voltage reference device, having first and second electrodes, is connected so that the second electrode is connected to the second terminals. A first DC amplifier has an input circuit connected between the first input terminals and the first electrode, and an output circuit connected between the first output terminals and the first electrode. A second DC amplifier has an input circuit connected to the input circuit of the first DC amplifier and an output circuit connected to the output circuit of the first DC amplifier. The second DC amplifier, besides sharing the current load requirements with the first DC amplifier, also controls a bias current through the voltage reference device.

Abstract: In a power distribution system having a first conductor carrying a current I.sub.1 and a second conductor carrying a current I.sub.2, in the same direction as I.sub.1, a differential current detector sensing when .vertline.I.sub.1 -I.sub.2 .vertline. exceeds a predetermined level, I.sub.3. The detector comprises a ferromagnetic yoke having first and second parallel bores accommodating the first and second conductors respectively. The first and second bores are interconnected by a coplanar slot in the yoke which extends transversely therebetween. The yoke further includes a third bore disposed between the first and second bores and orthogonal thereto. A reed capsule switch having two mutually exclusive conductive states extends through the third bore and is responsive to the flux generated by the currents I.sub.1 and I.sub.2, such that when .vertline.I.sub.1 -I.sub.2 .vertline..ltoreq.I.sub.3 the reed switch exhibits one conductive state and when .vertline.I.sub.1 -I.sub.2 .vertline.>I.sub.

Abstract: A compensation circuit connected across the source and gate electrodes of a MOSFET switch provides a compensating voltage across these electrodes such that the value of the ON resistance, R.sub.ON, from source to drain remains constant despite ambient temperature variations and in the presence of an analog input signal the compensation circuit provides a compensating voltage across these same electrodes such that the value of R.sub.ON remains constant despite variations in the amplitude of the input signal.

Abstract: Apparatus for reducing the susceptibility of line signal repeaters to induced currents includes a zener diode/diode stack which provides the line repeater with a constant voltage drop when the DC line current is above the minimum required bias current. When the DC input current plus an induced component from the line exceed the load requirements of the repeater, the excess current is conducted through a blocking diode to charge an energy storage device. But, when the DC input current and the induced component oppose each other, the energy stored in the energy storage device is used to supplement the input current to just maintain the required repeater voltage.

Abstract: A receiver is provided for utilization in a protective relaying modem to effectively distinguish between two mutually exclusive signal frequencies in a given frequency channel and which are respectively indicative of a "fault" or "no-fault" condition in a remote power transmission line. The received signals are coupled to a channel detector which utilizes a local oscillator and mixers to translate the received signal down in frequency so that simple low pass filters can isolate the desired frequency channel. The outputs of the low pass filters are operated on by a combination of multipliers and differentiators to generate an AM related output and a FM related output. The FM signal output of the channel detector is DC in nature and has an amplitude proportional to the deviation of the received signal frequency from the center frequency of the channel. This signal is used by separation circuitry to ascertain a fault or no-fault condition.

Abstract: A phase-locked loop is disclosed having a phase comparator, a switched lowpass filter, a voltage controlled oscillator, a loss of lock detector, and a charging circuit. The switched lowpass filter has two different bandwidths: the first bandwidth has a wide frequency response for use during acquisition periods for rapid acquisition, and a second bandwidth has a very narrow bandwidth for use during normal tracking for tight control of the voltage controlled oscillator. A loss of lock detector controls the particular filter bandwidth state by causing certain filter components to be switched in and out according to the presence or absence of phase lock condition. A charging circuit, used in conjunction with the particular lowpass filter section not operative during acquisition, charges the energy storage components used in this section of the filter to preclude transients from occurring when these components are switched back into the lowpass filter.

Abstract: A time-division multiplexing system wherein N parallel digital signals having an average bit rate of f.sub.1 are interleaved by a multiplexer to form a single composite line signal of bit rate f.sub.2, where f.sub.2 > NF.sub.1. Prior to multiplexing, signal gaps having a predetermined duration and having a fixed repetition rate are inserted into each of the N parallel signals. Adding gaps to each digital signal permits the bit rate between gaps to be increased to f.sub.2 /N, a submultiple of the composite line signal bit rate. The gap duration and their occurrence is such so as to maintain the average bit rate of each digital signal at f.sub.1. Each digital signal with the added gaps is then interleaved to form the composite line signal having the desired bit rate of f.sub.2. The interleaved gaps form empty time slots in the composite signal into which one or more signaling bits are added.

Abstract: Disclosed is a digital multiplexer which combines N parallel bit-synchronized digital signals, each of bit rate f.sub.1, into a single composite line signal of bit rate f.sub.2, where f.sub.2 > Nf.sub.1. Before the individual bits are interleaved, each digital signal is converted to a submultiple of the line frequency, f.sub.2. By inserting gaps having a predetermined duration and occurring at a fixed rate into each of the N digital signals, the bit rate f.sub.1 of each bit stream is increased to f.sub.2 /N. This is done without sampling any bit more than once. A multiplexer sequentially interleaves each bit from the N converted bit streams along with the gaps in each bit stream, forming the composite signal of bit rate f.sub.2. The interleaved gaps form empty time slots in the composite signal into which one or more signaling bits are added. Some of the added signaling bits carry framing information to lock the transmitter and receiver together.

Abstract: A diode switch device coupled between two circulators provides signal continuity around an active radio frequency circuit during a failure mode caused by a loss of local supply voltage. Under a normal nonfailed condition, the diode switch short circuits the bypass path, thereby preventing the input signal from bypassing the protected circuit. In the protected failure mode, the short circuit is removed and the input signal is conducted around the failed active circuit.

Abstract: A digital phase detector which periodically detects the phase angle .theta..sub.k of a carrier signal in which data are encoded as discrete phase changes. A coherent or differential phase-modulated carrier signal is split into its in-phase and quadrature phase components R.sub.o Sin.theta.(t) and R.sub.o Cos.theta. (t). Each signal component is sampled at a predetermined modulation interval and converted into a digital word having the form R.sub.o Cos.theta..sub.k and R.sub.o Sin.theta..sub.k. In one configuration, the two signal components are applied to a digital divider network which forms the quotient .PSI. of the two digital words such that .vertline..PSI..vertline..ltoreq. 1. The quotient .PSI.is applied to a data look-up ROM, programmed for Tan.sup.-.sup.1 operation, which forms a digital reference phase angle .PHI.limited to an angle .ltoreq. 45.degree. is corrected by selection logic to form the desired phase angle .theta..sub.k. Once .theta..sub.