Abstract: A data transceiver includes a transmitter connected at one end of a data transmission line and a receiver connected at the other end of the data transmission line. At least some portions of the transceiver are formed in CMOS. A temperature compensation circuit is connected to selected components of the transceiver to correct for temperature-induced variations in currents through those components. The temperature compensation circuit includes a pair of transistors connected, respectively, in parallel conduction paths. The transistors have unequal emitter areas, and their gates are tied together. The current through the larger transistor varies directly with temperature, and this current is reflected in a current mirror transistor that is connected to the shorted gates of the transistor pair. Since in CMOS technology current varies inversely with temperature, the current through the mirror transistor provides temperature compensation for selected components of the transceiver.

Abstract: A method for providing a standard coordinated time throughout spatially separated functional modules of an industrial controller employs a module operating as a time-master which transmits a coordinated time value to various dependent modules through communication modules. The particular time-master is determined by an arbitration process among potential masters which examines a time quality value, indicating the precision of the time-master's clock, and incorporated in the transmitted synchronization signal. Upon the loss of a master or the introduction of a new master, mastership is reallocated so that the master time value is provided from that module having the best time quality. Offset caused by "ripple through" of the time value through communication modules is minimized by summing to that time value as it traverses a communication module with a time quantity measuring the processing time of the communication module.

Abstract: A repeater includes N repeater circuits coupled to integrator device in a star topology. Each of the N repeater circuits has an Input/Output port for transmitting a clock, data, control and collision signal. A request-for-access signal within the control signals is asserted as repeater circuit is requesting a data repetition. The integrator device has N Input/Output interfaces each of which is coupled to a corresponding Input/Output port, for selectively executing the data repetition and generating the collision signal, in response to the clock and control signals, so that the repeater functions as a single repeater.

Abstract: An apparatus for the wireless transmission of energy and data includes a transformer with two sides for transmitting energy in one direction and data in both directions. A circuit on both of the sides of the transformer controls and evaluates a course of the transmission. In a method for controlling and evaluating the apparatus, a primary-side switching path is interrupted for transmitting energy from the primary side to the secondary side. Data are transmitted from the primary side to the secondary side during an energy storage phase by briefly interrupting a primary-side switching path. Data are transmitted from the secondary side to the primary side in a period during an energy storage phase by a secondary-side load pulse. An information transmission is controlled with a trigger and evaluation device on the primary side and on the secondary side.

Abstract: Techniques for generating a line probing signal. The probing signal is comprised of a plurality of different tones, where the tones have a predetermined phase relationship. The signal may be sent over a communication channel, such as a telephone line. By so using the line probing signal, the non-linearity of the electrical characteristics of the telephone line may be measured with increased accuracy.

Abstract: A method and apparatus of frequency synchronization is described for a reference oscillator. Using a reference oscillator set to a first frequency, the process begins by scanning for a radio frequency carrier modulated with a predetermined pattern. The radio frequency carrier is located such that a received pattern comprising a frequency shifted version of the predetermined pattern is identified and time synchronization is established. The received pattern, the predetermined pattern, and stepped alterations to the first frequency are combined to provide a set of results that represent pattern correlation versus reference oscillator frequency. The first frequency is offset using the set of results, such that frequency synchronization is improved.

Abstract: An method and apparatus for computing a scalar projection of a vector onto another vector. The apparatus comprises a multiplying circuit and a summing circuit. The multiplying circuit is for multiplying a value representative of a first component of a first vector with a value representative of a first component of a second vector to provide a first intermediate value, and for multiplying a value representative of a second component of a first vector with a value representative of a second component of a second vector to provide a second intermediate value. The summing circuit sums the first and second intermediate values to provide a resultant value representative of the scalar projection of the first vector onto the second vector. The apparatus may further comprise a storing circuit and a selection circuit. The storing circuit is for storing the values representative of the first and second components of the first vector, and the values representative of the first and second components of the second vector.

Abstract: A radio frequency backbone communication system is offered for exchanging, a plurality of communicated signals between a central site (205) and a plurality of communication units (16-18) through a plurality of remote base sites (60-66). The system includes at least one mobile function transceiver (201-204) located at the central site (205), transceiving a communicated signal of the plurality of communicated signals on a shared communication resource of a base site of the plurality of base sites (60-66) and, means for synchronizing a transceiver at the base site to the communicated signal of the at least one mobile function transceiver (201-204).

Abstract: A digital filter 23 receives a control signal which specifies what filter coefficient values should be used. The control signal can be changed repeatedly so as to dynamically select the coefficients in response to the value of a control parameter. The filter 23 can be configured as a data rate converting filter in which the control signal represents the current phase relationship between the input data stream and the output data stream. The phase control signal can be provided as the phase output of a numerically controlled oscillator 67 having an oscillation frequency which is a multiple of one of the data rates and which is clocked at a multiple of the frequency of the other data rate. The data rate converter can be used as part of a data modulator or demodulator, thereby allowing an analog-to-digital converter 19 or a digital-to-analog converter 143 of the modulator or demodulator to run at a fixed arbitrary frequency substantially regardless of the data rate of modulated symbols.

Abstract: At least one communication equipment connected to a communication infrastructure uses a first data coding format different from a second format used within the infrastructure which further comprises at least one data transcoder for converting data coded to the first format into data coded to the second format and vice versa. A transcoder is provided in the infrastructure in the vicinity of the connection to each of the equipments using the first format. The method of transmitting data between at least two of the equipments determines, on the basis of the data format used by each of the equipments between which data is to be transmitted, whether it is necessary to use a transcoder to transmit said data. If so, the transcoder nearest the equipment using the first format is activated so that the data is conveyed in a form coded to the second format in the infrastructure and changes from the first format to the second format or vice versa as close as possible to the equipment using the first format.

Abstract: Data are transmitted using quadrature amplitude modulation to select for transmission symbols from two (or more) different signal point constellations; constellation switching being used to facilitate transmission of a non-integral average number of bits per symbol and/or frame synchronization. Trellis shaping (where redundancy is introduced and selection of constellation "regions" performed over a number of symbols so as to minimize transmitted power) is employed; switching is provided so that power information (from stores is available appropriate to the constellation in use for each respective symbol. Synchronization may alternatively be provided by substitution outside the power control loop, of a symbol from an outer region for one selected from an inner region of a constellation. In another aspect of the invention, constellation-switching is employed within frames of A symbols, where A is not a power of two.

Abstract: A low power OFDM signal may be transmitted in an environment where it is subject to interference from other transmissions, e.g. broadcast television services. In a receiver interference is reduced by ignoring information modulating OFDM carriers at the frequencies corresponding to the carriers of the interfering transmissions; adjacent channel interference is reduced by ignoring data on OFDM carriers at the band edges and interference from third order intermodulation products is reduced by the ignoring OFDM carriers affected. Image channel interference is reduced by using an intermediate frequency for a first mixing process in the receiver such that the image channel interference affects OFDM carriers at frequencies which are already being ignored by the receiver. Preferably no data is modulated onto OFDM carriers which are to be ignored by the receiver. Preferably the modulation of the OFDM carriers is arranged so as to produce a real baseband representation of the OFDM signal.

Abstract: Before transmitting signals to a receiver, the signals are subjected to adaptive prediction to generate a residual signal for transmission, and the residual signal is then transformed into frequency domain coefficients, the coefficients are grouped together to form vectors, and the vectors are then quantized.

Abstract: A surface acoustic wave (SAW) device is described that comprises a piezoelectric medium using input and output transducers for launching and detecting a surface acoustic wave on the piezoelectric medium. In particular, a device is described that uses a special combination of transducers for the direct generation of a coded minimum shift keyed (MSK) waveform from an input impulse waveform. The same device is used for the direct detection of an input MSK waveform in order to generate an impulse waveform with sidelobe characteristics similar to those expected from a specific code. The SAW device provides the advantages of MSK encoded waveforms for spread spectrum applications and the advantage of implementing such entirely on a SAW substrate.

Abstract: An error-correcting tandem encoding system includes a transmitter section and a receiver section. The transmitter section comprises a multiplexer for multiplexing data and voice signals supplied thereto, a Reed-Solomon encoder for Reed-Solomon-encoding an output signal from the multiplexer while interleaving the output signal without causing a delay, a convolutional encoder for convolutionally encoding a Reed-Solomon encoded signal from the Reed-Solomon encoder, and a PSK modulator having a fixed bit rate for phase-shift-keying an output signal from the convolutional encoder.

Abstract: Signals representing navigation messages from four GPS artificial satellites are received by a GPS receiver and supplied to receiving processors of respective channels, which spectrally reverse-spread and demodulate the signals by way of PSK to produce the navigation messages. The navigation messages are then supplied to a CPU that determines the position of the GPS receiver using satellite time and orbit data contained in the navigation messages. The CPU determines whether each channel is synchronized or not based on the level of a spectrally reverse-spread output (correlated output) signal. If a channel is out of synchronism, the CPU effects a synchronization process. After the synchronization process, the CPU obtains time base data equal to or higher than a bit number. To obtain such time base data in a channel after the synchronization process, the CPU uses time base data equal to or higher than a bit number of another channel that has already been synchronized.

Abstract: In a method for limiting the bandwidth of a selected binary signal (B), there is produced a modulated digital signal (D) which presents a continuous series of changes in signal level. The two occurrent logic states (1,0) are each represented by a respective symmetrical pulse train, wherein the frequencies f1, f2 of the pulse trains are mutually different. The higher frequency f2 is equal to the number of bits transmitted each second divided by two herz. The transition between the two pulse trains is arranged so that the integral of the resultant signal will be zero within the duration of three of four data bits. In a preferred embodiment of a coder and decoder each include a code word counter which, together with a combinatory logic circuit (code word table) activates or is activated by a shift register for transmitting or receiving respectively the modulated digital signal.

Abstract: A method and apparatus of estimating a data sequence transmitted using a Viterbi algorithm, are disclosed. Sampled values of incoming data are acquired at a predetermined time interval into a memory. Subsequently, a plurality of sampled values are retrieved from the memory. Further, a plurality of receive signal replicas, which have been previously prepared and stored in another memory, are retrieved. A plurality of receive signal replicas are determined by multiplying the sampled values by the receive signal replica coefficients. Branch metrics are then determined using the sampled values of the incoming data and the receive signal replicas. A data sequence is estimated using the branch metrics according to the Viterbi algorithm.

Abstract: A radio communication apparatus comprises a detecting circuit for detecting a change of a received frequency of a radio communication channel during a communication and outputting a digital detection signal, a pulse width modulating circuit, and a smoothing circuit. The pulse width modulating circuit pulse-width modulates a pulse signal having a predetermined frequency in accordance with the digital detection signal output from the detecting circuit. The smoothing circuit smoothes the pulse-width modulated circuit output from the pulse width modulating circuit and generates an analog control signal. A transmission local oscillating frequency is controlled in accordance with the analog control signal.

Abstract: A communication apparatus includes a comparator comparing the voltage at one external bus with that at another external bus, and an oscillator. The comparator has a high speed operation mode and a low speed operation mode, and the oscillator has an oscillating operation mode and a non-oscillating operation mode. A sleep signal is supplied to the communication apparatus, to put the comparator in the low speed operation mode and put the oscillator in the non-oscillating operation mode. When a fall or a rise is detected in an output of the comparator, the oscillator is changed to the oscillating operation mode, and thereafter, the comparator is changed to the high speed operation mode.