Abstract: A method and associated system for providing multi-channel transmission of digital and broadband video information in optical fiber communication for local area networks through frequency-division-multiplexing, comprising the steps of generating a plurality of closely spaced optical carrier wave pairs with the optical carrier waves within each optical carrier wave pair having a predetermined separation frequency between one another, assigning each of the plurality of optical carrier wave pairs to a predetermined frequency slot and optically combining the plurality of optical carrier wave pairs to provide a multiplexed optical output wave. Advantageously, in addition to direct detection the plurality of optical carrier wave pairs may be detected by opto-electronic heterodyne detection and/or incoherent optical-heterodyne detection to electronically recover the optical carrier wave pairs.

Abstract: The invention provides a method and system for speaker enrollment, as well as for speaker recognition. Speaker enrollment creates for each candidate speaker a set of short acoustic segments, or templates, of phonemic duration. An equal number of templates is derived from every candidate speaker's training utterance. A speaker's template set serves as a model for that speaker. Recognition is accomplished by employing a continuous speech recognition (CSR) system to match the recognition utterance with each speaker's template set in turn. The system selects the speaker whose templates match the recognition utterance most closely, that is, the speaker whose CSR match score is lowest. The method of the invention incorporates the entire training utterance in each speaker model, and explains the entire test utterance. The method of the invention models individual short segments of the speech utterances as well as their long-term statistics.

Abstract: There is disclosed a technique for interfacing various subscriber groups having different security levels which subscribers are associated with the same telephone system. According to this invention, every terminal element or subscriber has a programmable frame delay for the out and in registers associated with the switching network. In this manner, each subscriber of the same priority will receive the same delay on the transmit and receive paths. This delay is accommodated by means of an up or down counter which is inserted in the frame sync signal to the appropriate input and output registers. The input and output registers are controlled according to the priority of the subscriber, such that there is a complementary delay in the receive path and the transmit path so that the total delay for the same priority subscriber is equivalent to one complete frame. In this manner, only subscribers of the same priority can communicate with each other.

Abstract: A liquid crystal polarization reorientation cell includes Helmholtz coils disposed on either side of the cell to provide a magnetic field that is substantially perpendicular to the transparent members. The energizing of the magnetic field is utilized to selectively reorient the polarization of at least one frequency of an incident light beam.

Abstract: Integrated circuits are tested prior to separation from a processed wafer. ach circuit has photoreceivers coupled via metallization tracks to an adjacent circuit. The receivers are used for the input of high speed optical test signals. The intercircuit coupling tracks are severed when the wafer is scribed to separate the individual circuits thus removing the electrical parasitic effects of the receivers.

Abstract: A digital data and orderwire combiner employs a first and a second inverting gate amplifiers. The first amplifier receives the orderwire signal which is a low rate digital signal, while the second amplifier receives the data signal which is of a higher rate. The amplifiers have a common ground return where current through the amplifiers is directed through a resistive impedance network. The amplifiers as coupled together providing a 3-level amplitude modulated signal indicative of the combined data and orderwire signal. In order to reduce jitter, a portion of one of the signals is directed from one amplifier to the other. The configuration assure low jitter operation while producing reliable voltage levels indicative of 3-level amplitude modulation.

Abstract: An antenna feed network implemented preferably in stripline for connecting the elements of a linear or planar array with a common port for transmit/receive operation. The network acts as a power divider/combiner and is entirely reciprocal. The network is realized in the form of a pattern of conductive traces on a single dielectric sheet of the stripline arrangement between parallel, spaced ground planes and does not require interconnections among multiple planes. The network may be utilized as a single or multiple beam forming network with the path lengths to the respective array radiators patterned to achieve a frequency scanning or beam normal array design.

Abstract: There is disclosed a Zero IF modulator apparatus for modulating carrier signals with baseband signals, the modulator includes digital logic circuitry including a sine/cosine amplitude converter which is responsive to the baseband signals for providing first and second digital quadrature baseband signals. These digital quadrature baseband signals are then employed by coupling the same to digital-to-analog converters where the outputs of each converter is indicative of a first and second quadrature signal. These signals can then be translated to a given carrier signal for transmission over a desired communication channel.

Abstract: The spread spectrum communication system terminal comprises a first subsystem including a first arrangement to encode a locally generally digital data with an error correcting code, a second arrangement for spectrum spreading of the encoded locally generated digital data in at least one mode of operation of the communication system terminal, a third arrangement to receive remotely generated error correcting code encoded digitla data spectrum spread in the one mode of operation and a fourth arrangement to recover the remotely generated digital data. In addition, a second subsystem includes a fifth arrangement frequency hopping the encoded locally generated digital data prior to transmission to a remote location and a sixth arrangement frequency dehopping the encoded remotely generated digital data received from the remote location.

Abstract: Apparatus for measuring the modulus of elasticity of a sample specimen of a given thickness and area includes means for mounting one surface of the specimen on a rigid reference plane and an opposing surface of the specimen is then mounted on a rotatable surface. A torque arm coupled to the rotatable surface applies a predetermined torque which effectively causes this surface to rotate thereby twisting the specimen through a given angle. The angle is measured by means coupled to the rotatable surface, and based on the measured angle, one can calculate the modulus of elasticity in regard to the measured angle and in regard to the applied torque. The apparatus and methods essentially measure the modulus of elasticity through angular displacement of the specimen.

Abstract: A liquid crystal switching device utilizing the Brewster angle includes a Brewster angle polarizer disposed such that an incident light beam of the device impinges thereon at an angle approximately equal to the Brewster angle.

Abstract: A pulse modulator for a radar system employing resonant charging of a pulse forming network and circuits for periodically discharging the network to form a power pulse applied to a microwave transmitter such as a magnetron, for example. The system includes circuits for controlling the pulse forming network charge effective at a time ahead of the discharging of the network, thereby to stabilize (regulate) the power pulse amplitude. The circuits shown provide for introduction of an increment of charge current independently of the resonant charging current of a magnitude determined by evaluation of the pulse forming network terminal voltage.

Abstract: The gate of a gallium indium arsenide FET grown on an indium phosphide substrate comprises a top layer of GaInAsP (band gap 1.2 eV) a middle layer of GaInAs and a bottom layer of InP. This can be etched to produce an overhanging top layer which allows self-aligned gate contact metallization avoiding the registration problems of a further masking stage.

Abstract: A orderwire detector circuit operates to identify whether an orderwire signal is of a digital or of an analog format. The orderwire signal is conveniently combined with a high speed data signal. The circuit operates to filter the high speed data signal from the orderwire signal and then square and retime the orderwire signal by means of a stable clock source. The orderwire signal is delayed by one bit and these bits are then compared to determine whether or not over a long period a certain voltage exists. If the proper voltage level exists after a plurality of samples, then it is assumed that the orderwire signal is a digital signal. Depending on the voltage detected, at the end of a predetermined sampling period, one can therefore discriminate between a signal orderwire signal or a analog orderwire signal.

Abstract: A multiple wafer scale assembly apparatus includes first and second wafer scale assemblies connected to termination pins in such a fashion that the completed assembly is operatively self contained.

Abstract: There is disclosed an improved double detection receiver for detecting pulsed RF carrier signals. The receiver employs first and second channels with the first channel being a narrower band than the second channel. Each channel is associated with signal detection circuit to provide first and second detected output pulses. These pulses are summed or substracted to provide an output pulse indicating the sum or difference of each channel signal and this output pulse is appplied to a frequency comparator. One of the detected signals is also applied to a signal strength comparator whose output is gated via gating circuit with the output of the frequency comparator to provide a pulse present output for the presence of both input signals at said gating circuit. The use of the frequency comparators assures improved operation of the double detection receiver.

Abstract: A high frequency, e.g. millimeter wave, semiconductor diode structure includes a buried layer of n.sup.+ -type material and a surface layer of lightly doped n-type material on which a Schottky barrier contact is disposed. The n.sup.+ -type layer provides a low series resistance thus permitting high frequency operation. The structure is compatible with MESFET processing techniques and may thus be incorporated in an integrated circuit.

Abstract: There is disclosed an electronic float switch circuit which employs simple immersion probes, one of which is associated with a high fluid level and the other with a low fluid level. Each of the immersion probes operates in conjunction with an oscillator, a detector and a comparator. Essentially, when the associated immersion probe is immersed in a fluid, the oscillator ceases oscillations which therefore provides a first low voltage level via the detector to the comparator to therefore change the state of the comparator. The comparator associated with the high and low level probes operate to set and reset a DC flip-flop which in turn controls an opto-isolator device to trigger a triac. The triac operates the pump. When the fluid level reaches below the level of the low probe, the circuit is disabled allowing the vessel again to be filled with water to allow the pump to operate between the high and low levels by means of the electronic circuit.

Abstract: An improved serpentine feed and method of making same. The invention includes a block of conductive material having a primary microwave waveguide channel and at least one secondary channel. Each secondary channel has at least one broadwall common to the primary channel. A high performance coupler is provided in the common broadwall by which microwave energy communicates from the primary channel to the secondary channel.

Abstract: A photo-detector includes a photoconductor comprised by a structure similar o a high electron mobility transistor (HEMT) but with the gate removed and the layer of high band gap thinned in order to reduce noise. On a semi-insulating substrate (8), an n-channel layer (9) is disposed and on channel layer (9) is disposed on n.sup.+ layer (7). Light incident on the n.sup.+ layer (7) causes electron-hole pairs to be generated in layer 9, the electrons and holes of which migrate to oppositely biased contact regions 10 and 11 respectively. The photoconductor is monolithically integrated with an HEMT (TI) (FIG. 3, FIG. 4 or FIG. 6) the latter comprising a pre-amplifier for a receiver circuit. In dependence on the materials chosen the photo-detector may be employed to detect wavelengths of the order of <8.88 .mu.m or <1.6 .mu.m.