Abstract: A sample and hold circuit is formed within an integrated circuit and has a small, substantially linear hold capacitance. The circuit includes a sampling switch, a hold capacitor, and a buffer amplifier. The buffer amplifier includes a common drain FET and a constant current source FET. The common drain FET provides an input which couples to the hold capacitor. The constant current FET isolates the source of the common drain FET from ground. The sample and hold circuit may be used as a wide bandwidth mixer. In a radio application, a pulse generator provides a stream of pulses in which the sampling rate times an integer number equals the RF frequency minus the IF frequency. The width of the sampling pulse is less than the period of an RF signal. In an oscillator application, the sample and hold circuit operates as a mixer in a frequency multiplying phase locked loop.

Abstract: An electronic apparatus for receiving and filtering high frequency waves comprises a sequence of T electroacoustic transducers each having multiple interdigital electrode fingers and a centerline located equidistant between its outermost electrode fingers. For a centerline-to-centerline distance of a first adjacent pair of transducers D.sub.1, and centerline-to-centerline distances of other adjacent pairs of transducers D.sub.2 to D.sub.T-1, then at least some of D.sub.2 to D.sub.T-1 differ from D.sub.1 by a non-integral number of wavelengths. The transducer array is symmetrical about a centerline and the number of fingers in each transducer varies, with an input or output transducer closer to either end of the sequence having more fingers than a like kind transducer nearer the center.

Abstract: A multi-channel receiver automatically determines the noise floor of each channel and resets the channel threshold based thereon while avoiding undesirable bias from weak non-noise signals. The power probability of uncharacterized input signals (non-noise content unknown) is computed and normalized to have a known probability that the power exceeds a first threshold. A second probability of exceeding a second threshold is determined and compared to a predetermined reference probability for a noise-only signal at the same threshold. If the computed second probability is not higher than the reference probability, then the uncharacterized signal is a noise only signal whose average is the noise floor for the channel. The threshold detection level is then set a predetermined amount above the noise floor. The process is automatic and compensates for receiver aging and ambient noise fluctuations with time and from channel to channel and for other changes.

Abstract: A method and apparatus for improved isolation of IF, LO, and RF frequency signals from the non-associated mixer ports (e.g., avoiding introducing RF frequency signals at the IF and LO ports, and similarly vis-a-vis other signals and ports), is provided by coupling a RF (or LO) signal to first ports of four-port first and second phase shift means, each having two signal output ports having 180.degree. phase difference for signals input from the first port, coupling the LO (or RF) signal to the first port of a third phase shift means, with two output signal ports having a phase difference of 180.degree., supplying the third phase shift means output signals to fourth ports of the first and second phase shift means, supplying the output signals of the first and second phase shift means to distinct ports of a five port mixer, and coupling an IF signal from the five port mixer to an IF port.

Abstract: A communication system service billing arrangement is described that adapts to system loading in realtime. As system loading varies, one or more individual subscribers units (ISU) of a communication system are provided with realtime information on the current cost of the communication service. The system determines the locations of the ISUs and the current loading there between and calculates a calling rate based at least on the current loading. This calling rate is sent to at least one of the ISUs whose operator can choose to connect or not connect the call between the ISUs based on the current realtime variable rate.

Abstract: A semiconductor assembly which includes a carrier and a semiconductor die is mounted on a printed wiring board. The die includes a top active surface and a bottom active surface. The two active surfaces are non-coplanar. The carrier is made from layers of a ceramic material. Holes are formed through all but one of the layers. The layers are laminated into an integral substrate, and the substrate is fired. The holes form a cavity into but not through the substrate. The number of layers, lamination pressures, and firing parameters are all adjusted in response to the thickness of the die to insure that the height of cavity walls approximately equals the thickness of the die. Continuous metallization is applied in the cavity and on a top surface of the substrate. The die is bonded in the cavity, and conductive bumps are formed on the die and the metallization.

Abstract: An apparatus which efficiently coordinates the association of resource and lot data in a manufacturing environment is disclosed. The apparatus includes a memory structure which associates resource and lot data only with other resource and lot data from a common dependency. A dependency is a characteristic of lots which share common resources and of resources which are shared by common lots. The memory includes nodes which describe the dependencies. The dependency nodes link to resource lists and to lot lists. The resource and lot nodes are part of resource and lot lists, respectively. Usage nodes are included to describe every use each lot makes of each resource. The usage nodes are linked to both resource nodes and lot nodes. The usage nodes are also linked together to define the order in which each lot uses its resources and the order in which each resource is used by its lots.

Abstract: A slave station, such as an orbiting satellite, and a master station, such as a ground control station, have their own lists of random pads. The master and slave station lists are identical. When the master station sends a critical command to the slave station, a selected one of the pads is combined with the command and transmitted to the slave station as a data communication message. Each pad is used only once. The slave station evaluates the received pad value using its version of the same selected pad. If the evaluation detects correspondence, then the command is authenticated and the slave station acts upon the command. The random pads are generated by the slave station. They are encrypted using an asymmetric encryption process and transmitted to the master station so that the master and slave stations will operate on common sets of pads.

Abstract: Automatic dynamic phase alignment of digital data, skewed with respect to a local clock, is obtained over a wide range of skew and skew frequencies. The system includes (i) an edge detector (52) containing predetermined delays (e.g., D1, D2, D3), (ii) delay registers (e.g., 72, 76, 84, 86), and (iii) a controller (54) for deciding when un-delayed and delayed data D0, D1, D2, D3 have transitions (102-138) which bracket corresponding clock transitions (100, 110, 120, 130) and regulating a subsequent two-stream parallel (e.g., bi-phase) register-multiplexer (56). The controller selects from the register-multiplexer (56), whichever of in-phase data D or delayed data DD has its transition spaced away from the clock transition by at least one delay D1, D2, or D3.

Abstract: A reflector arrangement for an acoustic wave device comprises an acoustic wave propagating substrate, reflection elements having at least two different widths separated by at least one gap breadth disposed on the acoustic wave propagating substrate. The at least two different widths enhance reflected waves produced by the propagating acoustic wave in such a fashion to as to achieve a total acoustic reflectivity which is independent of variations in width of the reflection elements.

Abstract: Orbiting satellites project footprints on the earth. Each footprint is divided into cells. Footprints of nearby satellites overlap one another, and the overlap increases as satellites approach a pole from the equator. The positions of all cells generated by all satellites are simulated at numerous points throughout an orbit. Cells are marked as being active or inactive to compensate for the overlap at each simulated point. Channel sets are assigned to cells within a reference footprint, and this assignment is propagated throughout all footprints in the referenced footprint's orbit. The channel set sequences are propagated to other orbits after taking into account inactive cells located near boundaries between the orbits. Each satellite stores channel set assignments for its cells at the various points throughout its orbit. All satellites switch their communication parameters at the same instant in response to the channel set assignments.

Abstract: A GPS receiver (10) with processor (14, 16), memory (18), input (20) and indicator (22), uses conventional code pseudorange and carrier phase to provide a compass function. The receiver antenna (12) is desirably held stationary while the directional vectors toward the satellites and for the desired heading (21) are computed, the rate of change of carrier phase determined and future carrier phase predicted. The antenna (12) is then moved in a closed path (11) while the differences between predicted and actual carrier phase are measured and converted to positional perturbations which are resolved along the desired heading (21) and normal thereto. As the antenna (12) moves around the closed path (11), the resolved perturbations have maxima, minima or change sign and the processor (14, 16) uses this to trigger the indicator (22, 222) so that the desired heading is apparent to the user.

Abstract: An apparatus for mixing electrical signals including in combination: first signal splitting means having a radio frequency (RF) port and first, second, third and fourth signal ports, second signal splitting means having a local oscillator (LO) port and first, second, third and fourth signal ports, intermediate frequency (IF) port, and mixer element means, the mixer element means coupled to the first, second, third, and fourth signal ports of the first and second signal splitting means and coupled to the intermediate frequency port means, for mixing two of the RF, IF, and LO signals to produce the remaining signal.

Abstract: A new method for Code Excited Linear Predictive (CELP) coding of speech reduces the computational complexity by removing a convolution operation from a recursive loop used to poll the adaptive code book vectors. In a preferred embodiment, an impulse function of a short term perceptually weighted filter is first convolved with perceptual weighted target speech and the result cross-correlated with each vector in the codebook to produce an error function. The vector having the minimum error function is chosen to represent the particular speech frame being examined.

Abstract: A shunt regulator for isolating a power supply and load is described which automatically adjusts the quiescent current though the shunt, and therefore its available dynamic range, in proportion to the load current fluctuations. A signal proportional to the load current fluctuations is differentiated, detected, integrated and fed back to control the bias on the shunt. When large load current fluctuations occur, the operating point of the shunt is shifted to higher current values so as to provide a large dynamic regulation range. When load current fluctuations are small or zero, the operating point of the shunt is moved toward cut-off, thereby reducing the dynamic range of the shunt and conserving power. This substantially reduces the power dissipation in the regulator because the shunt need not be constantly biased to handle the largest anticipated load current fluctuation.

Abstract: Efficient coding speech information for low rate (e.g., 600 bps) channels using a four frame superframe (SF) includes: (1) coding spectral information using alternative quantizers one of which is chosen for each superframe so that 3 bits/SF identify the optimal quantizer and 28-32 bits/SF contain the quantized spectral information; (2) coding pitch using 5 bits/SF if voiced and if unvoiced assigning the pitch bits to error correction; (3) coding energy using 9-12 bits/SF by a 4d vector quantizer (4dvQ); and (4) coding voicing using 3-4 bits/SF by a 4d VQ, for a total of 54 bits/SF including 1 sync bit and 0-1 error correction bits. When combined with a unique perceptual weighting scheme, output speech quality comparable to that of vocoders operating at almost four times the channel capacity is obtained.

Abstract: A communications network includes satellites, which serve as switching nodes and move in orbits about the earth. The network additionally includes stationary switching offices. Mobile communication units communicate with the network through the satellites using TDMA data packets and network control messages. The switching offices couple to PSTNs. Each mobile unit is managed by a nearby switching office that assigns a logical channel identification (LCID) value to the unit. The unit and network use the LCID value to identify the unit in network communications so that network resources are conserved. The network insures that LCID values assigned to opposing parties in a call are included in all TDMA data packets transported to the opposing parties. Satellites and switching offices use these LCID values as logical channel assignments which do not change throughout the duration of the call, in spite of movement by satellites.

Abstract: An environment which includes a communications network, user terminals, and an authentication center provides communication services only to legitimate subscribers. The center receives an equipment ID for each terminal and uses a secret key to encrypt the equipment ID with a user ID and an error detection code to form an encrypted block. This block is programmed into an authentication module and sent to the subscriber for installation in the subscriber's terminal. The center sends a public key to authentication nodes of the network. When the subscriber operates the terminal to gain access to the network, a log-on message, which includes the encrypted block and an unencrypted version of the equipment ID, is sent to an authentication node. The authentication node decrypts the encrypted block and evaluates the IDs to determine whether to grant access to services offered by the network.

Abstract: There is provided a method and means for controlling the amount of overlap and gaps in coverage of antenna pattern cells of a moving satellite communication system, by determining the relative spatial location of overlapping or gaping cells of converging or diverging satellites as a function of time; determining a point where antenna coverage of one or more cells from a first moving satellite will overlap or gap one or more cells from a second satellite; and turning off or on one or more of the overlapping or gaping cells so as to eliminate interference therebetween without leaving substantial coverage gaps between adjacent antenna patterns.

Abstract: An apparatus comprises a signal input and a sampler and analog-to-digital (A/D) converter coupled to the signal input. The sampler and A/D converter forms a digital pre-look signal from an input signal. The apparatus further comprises a digital memory coupled to the sampler and A/D converter. The digital memory stores sensitivity time control (STC) data and provides specific STC data in response to the digital pre-look signal. The apparatus further comprises a digital-to-analog converter coupled to the digital memory. The digital-to-analog converter converts the specific digital STC data to a first analog STC signal. The apparatus also includes a first comparator coupled to the signal input and to the digital-to-analog converter. The first comparator has an input for receiving the first analog STC signal. The first comparator compares a present input signal to the first analog STC signal to provide a detection signal.