Abstract: Provided is an apparatus for analysing digital radio transmissions which can provide an output indicating the condition of a digital transmission link. The apparatus operates by sampling received radio signals to produce for each sampling instant a signal or signals representative of the modulation state of the transmission at the sampling instant. The apparatus includes a processor which can receive and measure a given number of such signals. The processing means is arranged to process the signals according to one or more stored routines and generate one or more parameters which indicate the condition of the transmission. The apparatus includes means for representing the samples by digitally encoded numbers and the processing means arranges those samples into one of a plurality of groups according to the value of the number. The number of groups correspond to the number of modulation states. This technique allows the apparatus to carry out accurate analysis of the transmission.

Abstract: A fiber optic multiplexing controller for transmitting a separate original electrical signal to each of a plurality of signal receiving devices. Each separate original electrical signal originates from one or a plurality of signal sending units. A transmit section of the controller includes an encoder for encoding the separate original electrical signals into a single multiplexed electrical signal. The transmit section further includes a fiber optic transmitter for converting the multiplexed electrical signal to an optical signal. Thereafter, the optical signal is transmitted via fiber optics to a receive section of another identical controller. This receive section includes an optical receiver, provided for the purpose of receiving the transmitted optical signal and converting it to a multiplexed electrical signal. The multiplexed signal, whether electrical or optical, is made up of discrete portions. Each portion of the signal is devoted to a predetermined one of the separate original electrical signals.

Abstract: A multiplex transmission system, in which one of a plurality of nodes, as a transmission node, mutually coupled together through a transmission path transmits data frame by frame to at least one of other nodes as at least one of reception node, and the reception node returns a reception acknowledge signal to the transmitting node upon proper reception of the frame of data. A reception acknowledge signal area comprising a plurality of bits is provided following the frame transmitted from the transmitting node. The reception acknowledge signal area is divided into a plurality of bit areas which are respectively assigned to the plurality of nodes. The reception node returns the reception acknowlege signal to the transmitting node from the respectively-assigned bit areas of the reception acknowledge signal area.

Abstract: The present invention relates to a multichannel multihop lightwave communication network which allows packet concurrency in the network while avoiding the need for agile optical devices. The network comprises a lightwave communication medium (10) for supporting a plurality of independent user nodes; and a plurality of N network interface units (NIUs) (11). Each NIU is connected to the lightwave medium and one or more separate user nodes and comprises a trnasmitter section (28-35) and a receiver section (20-27) which are each fixedly assigned to transmit and receive, respectively, over a single channel or a plurality of separate channels to or from other NIUs of the network. In a connectivity pattern for one embodiment of the network, the NIUs are divided into k groups of p.sup.k NIUs such that each NIU of a first group of p.sup.

Abstract: A method is provided for use in a Token ring network including a plurality of stations serially connected by a transmission medium so as to form a closed loop on which packets of data are circulated, wherein each respective station includes a media access controller and a buffer memory, the method including the steps of transferring data of a respective packet from a media access controller to a buffer memory; storing the data in a sequence of contiguous memory locations in the buffer memory; in the course of the step of transferring the data, generating status information for the data; after said step of storing the data, storing the status information in the buffer memory contiguously with the stored data at the beginning of the sequence of memory locations in which the data are stored.

Abstract: An analog input signal is converted into a digital signal. The digital signal is shifted to the difference frequency region by mixing it with each of a sine wave local signal and a cosine wave local signal to obtain complex waveform data. On the other hand, a trigger signal is generated when a reference signal meets a specific requirement, and a frame composed of a fixed number of data is defined which is synchronized with the trigger signal. The complex waveform data of each frame thus defined is phase rotated so that its phase angle has a predetermined value, or the phases of the local signals are synchronized with the trigger signal so that the complex waveform data of respective frames have the same phase. The in-phase complex waveform data of plural frames thus obtained may also be averaged, if necessary.

Abstract: Variable-length codewords are grouped into successive N bit word groups in sequential order as received from a variable length codeword encoder. The N-bit groups are each stored in corresponding N-bit-wide memory locations in a buffer memory prior to transmission over a channel. The locations are filled to capacity on one clock pulse and emptied on a second clock pulse to efficiently utilize the memory at a given clock rate.

Abstract: In an optical fiber communication system that operates at a wavelength .lambda..sub.o and comprises optical fiber having a cut-off wavelength .lambda..sub.c >.lambda..sub.o, a "grating", with parameters chosen such that the grating causes resonant coupling between a predetermined guided mode (e.g., LP.sub.11) and a tunneling-leaky mode, can be advantageously used to remove unwanted guided modes. Such removal can substantially improve the bandwidth of such a system.

Abstract: A low cost, multipurpose digital IC is used as the basic building block in establishing a network communication system over a desired communication link. The digital IC can function as an addressable microcomputer interface between the network line and a remotely located microcomputer which may, for example, comprise any microprocessor based controlled product. In such mode, the digital IC's function is to take data from the network and pass it on to the remotely located microcomputer upon command from the central controller and to transmit data from the microcomputer to the central controller. The digital IC may also function as a nonaddressable microcomputer interface between the central or master controller and the network line. In such case the digital IC's function is to continuously take data from the central controller and place it on the network and take data from the network and pass it back to the central controller.

Abstract: Apparatus for transmitting optical signals from an unprotected environment to a protected environment are disclosed. The apparatus may take the form of a lightpipe which has a light transmitting core and a cladding material surrounding the core having an index of refraction lower than the core. The lightpipe is aligned with a photodetector by means of a retaining collar. An omnidirectional optical signal collector is also disclosed for receiving optical signals from any direction and relaying them to a secure photodetector.

Abstract: An optical frequency synthesizer and/or sweeper, whereby a coherent optical output light is obtained by using a wavelength stabilized laser and an optical phase locked loop wherein the frequency of the output has the characteristics of high accuracy, high stability and narrow spectral line width. The optical phase locked loop comprises a tunable laser, an optical frequency multiplier, an optical frequency shifter and an optical heterodyne detector, wherein the optical phase locked loop is capable of precisely outputting an arbitrary wavelength by feeding back an output optical frequency.

Abstract: The invention relates to a system to transmit digital signals reproduced from a compact disk player, a digital audio tape recorder or the like. In order to increase the S/N ratio of transmission of the digital signals, the occurrence probability of data to be transmitted is made low and light emission time of a light emission element is made small, and the peak value of emission is increased corresponding to the above reduction. As a result, the S/N ratio can be increased in the same transmission band as that in the prior art. In order to reduce the occurrence probability of data, a method of generating pulses at the leading edge and the trailing edge of a pulse signal or a method of compressing data is provided.

Abstract: An electro-optical transducer assembly for translating between an optical high speed serial data transmission path and parallel electrical data transmission paths is provided by a light emitting or light detecting device with serial terminals, a logic chip with timing, amplifying, serializing or de-serializing circuitry, and a multi-layer coupling chip with parallel input or output contacts mounted between the device and the logic chip for coupling the serial terminals of the device to the serial terminals on the logic chip and coupling the logic chip parallel terminals to the parallel input or output contacts.

Abstract: An analog-to-digital converter for use with a stepped square 2.sup.2n -QAM demodulator comprises a first group of (2.sup.n+1 -1) comparators for detecting signal points of a demodulated signal of a stepped square QAM system which are located within a 2.sup.n .times.2.sup.n square of the signal constellation of the stepped square QAM system, and a second group of four comparators for detecting signal points located outside of the square. A first logic circuit is provided to convert the outputs of the comparators of the first group to a first multibit digital signal representative of the signal points located within the square, and a second logic circuit is provided for converting the outputs of the comparators of the second group to a second multibit digital signal representative of the signal points located outside of the square.

Abstract: A packet switching module connects to a multiplexed carrier line which has at least an input line and an output line. A receiver circuit receives an information frame over the multiplexed carrier line. The information frame has a predetermined format which includes a physical destination address. A plurality of processing modules and a controller are connected to a common memory and switching the packets according to the destination addresses. The new information frame is outputted on the multiplexed carrier line by a transmitter circuit.

Abstract: The present invention relates to a circuit which controls the decision timing for deciding multi-level signal to the optimum decision timing. The control is carried out in such a manner as reducing deviation of phase of decision clock by deciding slope of multi-level signal at the center decision timing from the decision data at least continuous three decision timings and deciding deviation of decision timing from the slope and error signal at the center decision timing. Moreover, two kinds of slope decision are realized and the desired slope decision can be selected in accordance with the line condition.

Abstract: A data communication apparatus comprises means for registering a destination station identification code number, means for storing information, and control means for setting a communication mode by the destination station identification code registration means and the information storing means.

Abstract: A microphone is provided in which two circuit boards are held in spaced parallel position by each being connected at one end to a supporting member and by each resting at the other end in a pair of stabilizing grooves located within the microphone head. A battery holding assembly has attached at one end the supporting member, and at the other end an antenna mounting surface onto which a coiled antenna is placed. A battery holding compartment is located between the supporting member and the antenna so that a battery held in the compartment acts as an addition to the antenna itself. A power and battery level indicator flashes on and off to warn that the charge of the battery is reaching a predetermined low point. The electronic circuitry for the indicator is also provided.

Abstract: Information is transmitted at microwave frequencies, the ground station being connected to a waveguide (25) and the station aboard a railway vehicle being connected to an antenna (26). Each station comprises a microwave generator (19) supplying a carrier, transmitters (3 through 7) supplying subcarriers, receivers (28 through 32) and a pilot generator (1). The carrier and subcarrier frequencies are multiples of the pilot frequency and the frequency difference between adjacent subcarriers equals the pilot frequency. A transmitter mixer (MTX) receives the carrier and the subcarriers and is connected to a circulator (24), itself linked to the waveguide (25) in the ground station and to the vehicle station antenna. A receiver mixer (MRX) is connected via a filter (23) to the circulator (24) and receives the carrier from the microwave generator; the latter mixer is connected to the receivers (28 through 32) to which it sends the subcarriers transmitted by the other station.

Abstract: A method for calibrating a remote pilot unit is provided wherein both the pilot receiver and the pilot transmitter are calibrated. A test signal of a known magnitude is applied to the pilot unit and the magnitude actually received by the pilot receiver is determined. The two magnitudes are compared and a correction signal is determined. To calibrate the remote transmitter, a signal of a nominal magnitude from the transmitter is applied to a measurement device and the determination is made by the measurement device of the actual magnitude applied. The actual magnitude and the nominal magnitude are compared and a transmitter correction signal is determined. The receiver correction signal and the transmitter correction signal are stored in permanent memory within the pilot unit. This process is repeated at a plurality of frequencies to provide a signature for both the transmitter and the receiver.