Abstract: A wavelength demultiplexer having at least two photodetectors is disclosed. The photodetectors are arranged in sequential layers along an optical path. The photodetectors differ in bandgap, and are arranged so that the optical signal passes through relatively larger bandgap photodetectors before being received by relatively smaller bandgap detectors. Each photodetector absorbs photons within a predetermined energy range and generates a voltage as a function of the absorbed energy. The photodetectors can be used to detect, and hence demultiplex, a wavelength-division-multiplexed signal.

Abstract: A method for estimating frequency moments of a database, the frequency moments F.sub.k of a sequence containing m.sub.i elements of type i, for 1<i<n, being ##EQU1## for each k.gtoreq.0. The method entails receiving a sequence of data elements for input to the database; selecting a subset of the sequence of data elements; initializing a counter corresponding to each data element of the subset; comparing data elements input to the database with each data element in the subset and incrementing counters of subset elements which correspond to the input data elements; computing a random variable for each data item in the subset, which depends on the counter of this subset item; and, processing the plurality of random variables to determine an estimate of the frequency moment. The estimated frequency moment is optimized to be accurate with a high degree of confidence.

Abstract: For use with a DC power supply having first and second output rectifying circuits couplable in alternative configurations to provide dual voltages at an output of the DC power supply, an adaptive voltage controller and a method of adaptively controlling the output voltage. In one embodiment, the adaptive voltage controller includes: (1) a configuration determination circuit, coupled to the output, that generates a configuration signal that is a function of a configuration of the first and second output rectifying circuits, (2) a voltage feedback circuit, coupled to the configuration determination circuit, that develops a voltage feedback signal based on the configuration signal and (3) a voltage control circuit, coupled to the voltage feedback circuit, that receives the voltage feedback signal and controls an output voltage of the DC power supply as a function thereof.

Abstract: A novel process for forming a window, illustratively, an emitter window BiCMOS process is disclosed. An anisotropic etch followed by an isotropic etch to open the window is disclosed. The isotropic etch prevents contamination of the substrate by the anisotropic etching process.

Abstract: A radio frequency (RF) test probe arrangement includes a test probe body with a probe for coupling with a RF port of a circuit to be tested, wherein the port has a RF terminal and a ground conductor in the vicinity of the RF terminal to define an operating impedance at the RF port. The probe includes an RF contact supported by the probe body for electrically contacting the RF terminal of the RF port of the circuit to be tested, and a ground contact fixed on the probe body in the vicinity of the RF contact, for electrically contacting the ground conductor at the RF port. A connector mounted on the probe body couples the probe with external test measurement instrumentation.

Abstract: An N-bit binary synchronous counter includes K counter stages, with each stage including N/K flip-flops or other suitable storage elements. A given one of the counter stages receives a carry-in signal generated by another counter stage or by a carry logic circuit. The given counter stage includes a selection circuit for selecting one of two precomputed values for application to an input of a storage element in that stage based on a value of the carry-in signal. The selection circuit may include a two-input multiplexer for each of the N/K storage elements of the given counter stage. The jth multiplexer includes a first input coupled to an output of the jth storage element, and a second input coupled to an output of a logic circuit. The logic circuit generates a logic function based on the output of the jth storage element and other lower significant storage elements in the stage.

Abstract: A telephone system and method where telephones automatically learn the required prefix codes used in a private system to reach a public telephone exchange. The telephone has a memory that stores the numbers of callers who have called that telephone. A microprocessor then compares each number dialed on that telephone to the stored numbers saved by the telephone. The comparison is done from the last digit in each number to the first digit in each number. If at least the last seven digits of a dialed number match at least the last seven digits of a saved number, then a match is considered to occur. By analyzing the numbers in a dialed number that are not the same as the numbers in a matched saved number, the microprocessor can determine a possible prefix code that was contained within the dialed number. By performing a statistical analysis of possible prefix codes, the microprocessor can determine the proper prefix code for the telephone.

Abstract: An interface device for mating transducer-based telephone handsets to a telephone, and particularly transducer-based telephone handsets having different electrical input/output requirements comprises: a current source device for providing current flow through a transducer of the telephone handset; a device for detecting the current flow through the transducer present in the telephone handset and generating a handset type signal according to the amount of current flow detected; and, an adjusting device for adjusting the electrical characteristics of audio signals to be transmitted according to the generated handset type signal. The interface device further includes a control device responsive to the handset type signal for maintaining the current source device in an ON state to provide a predetermined amount of current flow to the telephone handset, or an OFF state substantially reducing current flow to the telephone handset.

Abstract: An edge signal restoration circuit and method to enhance an edge of a signal decreases a rise and fall time of a propagating signal during transitions between logic states. The edge signal restoration circuit includes a first circuit to detect an edge of an input signal and to output a detection signal, and a second circuit to drive a next state of the input signal in response to the detection signal at approximately the same time as the first circuit detects the edge of the input signal. The edge signal restoration method detects a transition of the signal between a current state and a next state, and drives the next state onto the signal during its transition to that next state.

Abstract: A high speed logic module is formed to include a differential input formed as a pair of inductive transmission lines and a differential output also formed as a pair of inductive transmission lines. A pair of logic devices are included in the module, with the gate terminals of the devices coupled to separate ones of the input inductive transmission lines. The output terminals of the logic devices are coupled to separate ones of the pair of output inductive transmission lines. The effects of the intrinsic gate-to-drain capacitance C.sub.gd inherent in each logic device is compensated for by including a pair of cross-coupled neutralizing capacitors between the drain and gate terminals of the logic devices. Various logic circuits, such as oscillators, latches, delay lines, etc. can be formed using the differential, neutralized structure of the invention.

Abstract: The trackball mounting apparatus of the present invention functions to orient the data input device in an ergonomically correct mode. The preferred embodiment of the invention is in the form of a trackball connected to the personal computer via a cable and attached to the mounting apparatus in an orientation that is parallel to the normal position of the palm of the user's hand so that the user can maintain their hand in a normal at rest position while operating the data input device. The use of this apparatus therefore reduces the strain on the user's hand and arm muscles as well as reducing the extent to which the data input device protrudes from the side of the personal computer. Furthermore, this mounting apparatus enables the user to make use of an adjunct data input device, connected to the personal computer via a cable, as a stationary pointing device.

Abstract: Correction of a duty-cycle is performed for use with a divide-by-two phase-splitter to increase precision of the duty-cycle of an incoming local oscillator signal in order to provide more precise phase relationships during generation of a phase and amplitude modulated carrier. Phase-splitter input signals are generated by limiting the slew-rate of an incoming signal to produce an intermediate signal. The intermediate signal is clipped in relation to a reference level. The reference level is adjusted by a feedback signal to produce an adjusted duty-cycle signal as an output signal. The feedback signal is proportional to the adjusted duty-cycle signal.

Abstract: Methods and apparatus for determining mobile station position in a wireless communication system are disclosed. A mobile station of the wireless system includes a silent echo generation circuit which receives a transmit time stamp transmitted in a sync channel from a base station, and processes the transmit time stamp to generate a receive time stamp. The silent echo generation circuit transmits the receive time stamp back to the base station on a spurious-like echo carrier which is offset from a data carrier of the wireless system. The base station processes the transmit and receive time stamps to compute a first ranging value, receives corresponding second and third ranging values computed by two other system base stations which receive the echo carrier and its time stamp, and processes the first, second and third ranging values to determine a position vector indicative of the position of the mobile station.

Abstract: An apparatus for accessing fibers in an optical fiber ribbon by separating the ribbon into first and second portions has a lower element having a slot therein for holding the ribbon, a coupling element to which the lower element is fixedly mounted, and a slotted upper element vertically and rotatably movable on the coupling element. The upper element can be raised to permit insertion of a fiber ribbon into the two slotted elements, after which it is lowered and twisted on the coupling element to separate the ribbon into two parts.

Abstract: A digital communication system for transmitting and receiving a hybrid optical and RF communication signal. The system includes a hybrid transmitter that incorporates an optical transmitter, an RF transmitter, and a transmitter control unit that controls both transmitters. Similarly, a hybrid receiver includes an optical receiver and an RF receiver, both connected to a receiver control unit. When an optical carrier signal is transmitted to the optical receiver by the optical transmitter, the transmitter control unit causes the RF transmitter to transmit an RF synchronization signal along with the carrier to provide a timing base for the digital pulses carried by the optical signal. The receiver control unit uses the timing parameters from the RF signal to reconstruct the received optical carrier signal that may have deteriorated during the transmission due to ambient optical noise, attenuation or obstructing objects.

Abstract: A multirate network is Wide Sense Non Blocking with a new routing algorithm classifying requests into large, load greater than 1/(1+p), and small groups, where B is the upper load bound of any given request and p=.left brkt-bot.1/B.right brkt-bot.. Where B is less than 31/32-.beta./4, substantially 2.beta.n(P+1)(B+p-1)/p2 center interconnection units are restricted for carrying large requests only. For all other B, substantially 2.beta.n center interconnection units are restricted. Using this routing algorithm, general multirate WSNB is guaranteed with substantially the lesser of 2f(p)+1+3.75.beta.n and 2n.beta.(P+1)(Bp+B+p-1)/p.sup.2 interconnection units where n is the number of inlets per input stage switch, .beta. is the ratio of load capacity of external links to the input and output stages, and the load capacity of the internal links connecting the center stage to the input and output stages.

Abstract: A frequency synthesizer is supplied with an input signal of frequency .function..sub.i to provide an output signal .function..sub.o where .function..sub.o=.function..sub.i M/N and M and N are integers. The input signal is first applied to a divider circuit for division by M/K where K is an integer and the resultant is applied as inputs to a phase locked loop. The phase locked loop includes a ring oscillator of frequency .function..sub.i N/M, a frequency multiplier circuit for multiplying by K, and a frequency divider circuit for dividing by N. The ring oscillator uses a combinational logic circuit that combines the outputs of four differential delay elements to produce a frequency multiplication of four.

Abstract: In order to make the world wide web truly world wide, a method and apparatus is provided such that accesses to a world wide web home page can be responded to with a home page adapted to the language or dialect that is most likely to to match the native language or dialect of the user. To provide this, the user's country code, numerical node address, or the user's client system address is matched in a database to provide the most likely language. Other languages may be selected if the choice is incorrect and the database will remember that selection for future accesses. Further, since some data transmissions are regulated by national law, the user and client location information is used by the server to prevent the server or the client from violating their respective national laws.

Abstract: A method is described for eliminating the impact on an output of an adaptive equalizer due to the occurrence of "false" coefficients of such an equalizer. In particular, a method is provided for selecting a threshold as representing the smallest expected "ghost" value to be encountered by the filter/equalizer, and thereafter causing coefficients having values less than such threshold to be set to zero.

Abstract: The invention provides an alternative to conventional sol-gel methods that utilize undesirably high amounts of a stabilizing agent such as TMAH and a gelling agent such as methyl formate. The method involves the steps of (a) providing a colloidal silica dispersion containing a stabilizing/gelling agent, where only a portion of the molecules of the agent ionize, and (b) subsequently adding to the silica dispersion a pH-reducing additive. The stabilizing/gelling agent has a dual function. The agent, e.g., an amine, initially acts as a stabilizer in the silica dispersion in that a portion of its molecules ionize, while an appreciable amount of the agent remains non-ionized. The agent later transforms in situ to a gelling agent upon addition of a pH-reducing additive. Specifically, as the pH-reducing additive lowers the pH to values at or around the pK.sub.