Abstract: A timing recovery device for CAP/QAM modems includes an equalizer filter designed to monitor the movement of the filter coefficients within a memory buffer and to adjust the relative position of the filter coefficients within the memory buffer so that the coefficients remain substantially centered within the buffer.

Abstract: A system and method for transmitting data over a channel, in which the data are categorized in at least two different categories. For example, the data are categorized according to the effect on perceived degradation on the data when error mitigation is performed on the data. Corrupted data of the first category are replaced using a first replacement method, such as retransmission and forward error correction. The corrupted data of the second category are replaced using a second replacement method different from the first replacement method, e.g., error mitigation or interpolation.

Abstract: A joint demodulator is configured to generate an estimated first frequency or first frequency error for the first signal and an estimated second frequency or second frequency error for the second signal. A first long-term automatic frequency control is responsive to the estimated first frequency or first frequency error, wherein the joint demodulator is responsive to the first long-term automatic frequency control. A second long-term automatic frequency control is responsive to the estimated second frequency or second frequency error, wherein the joint demodulator is responsive to the second long-term automatic frequency control. First and second local automatic frequency controls also may be included in the joint demodulator, wherein the first long-term automatic frequency control is responsive to the first local automatic frequency control and the second long-term automatic frequency control is responsive to the second local automatic frequency control.

Abstract: Apparatus, and an associated method, for encoding digital data to be communicated by a sending station, such as a base transceiver station of a cellular communication system. Space-time diversity is provided pursuant to the encoding, thereby to facilitate communication of data upon communication channels susceptible to fading conditions. A systematic and recursive space-time coder includes a coset selecting coder for forming coset addressing values used in connection to a multi-dimensional constellation. The coset addressing values are used by a signal entity selector to select a multi-dimensional constellation entity.

Abstract: A radio, and related methods of radio communication, consisting of a multi-modulation modem, wherein the multi-modulation modem that modulates and demodulates signals using a plurality of modulations. The radio also comprises a frequency converter coupled to the multi-modulation modem for converting the signals to a radio frequency and a transceiver unit including an antenna coupled to the frequency converter for transmitting the signals over a radio communications link. The multi-modulation modem includes a modulator that includes a modulation selector unit that selects respective ones of the plurality of modulations to modulate the signals. The multi-modulation modem also includes a demodulator for demodulating the signals having been modulated using the plurality of modulations.

Abstract: An amplitude modulation detector use peak detection. A CAS (Customer premise equipment Alert Signal) detection apparatus and a caller information detection apparatus use the peak detection and methods for CAS and the caller information detection. The CAS detection apparatus includes a mixing unit, an amplitude modulation detection unit, and a frequency discriminating unit. The mixing unit mixes two or more frequency components of the input signal to generate an amplitude modulated signal including a carrier and an envelope. The amplitude modulation detection unit measures the envelope. Also, the frequency discriminating unit detects whether the frequency of the envelope is in a predetermined range to discriminate whether the CAS is present. Thus, the existence of the CAS can be detected through a single path by mixing a dual tone CAS signal, and can be accurately detected by discriminating the frequency the envelope.

Abstract: A method of determining accurately and expeditiously the frequency of a coherent signal from an incoming electrical signal is disclosed. The method comprises the steps of: generating a time sequence of sampled data signals from the incoming electrical signal; detecting the coherent signal in the time sequence of sampled data signals and generating a frequency estimate thereof; and determining the frequency of the detected coherent signal based on a function of the frequency estimate and a time segment of sampled data signals associated with the coherent signal. A system for performing the same is also disclosed.

Abstract: A multiple carrier communication system includes a primary impulse shortening filter that receives an output signal of an analog to digital converter and accepts coefficients. A secondary impulse shortening filter receives the output signal of the analog to digital converter, outputs an output signal, and passes coefficients to the primary impulse shortening filter. A reference signal generator outputs a reference signal. A comparator compares the output signal and the reference signal and outputs a resulting error signal. An adaptive processor computes coefficients for the secondary impulse shortening filter based on the error signal.

Abstract: A carrier changer and changing method capable of generating a plurality of pseudo carriers by one pseudo carrier generator is provided. In the carrier changer, a pseudo carrier generator selectively generates one of a plurality of forward pseudo carrier signals based on a forward signal by a time division. A forward signal processor receives the forward signal and generates a pseudo carrier generating signal based on the forward signal, and outputs the forward signal and the pseudo carrier signals generated by the pseudo carrier generator. A power amplifier amplifies powers of the forward signal and pseudo carrier signals from the forward signal processor. Since an output of a phase locked loop is generated according to a variable phase locked loop data, pseudo carrier signals having different frequencies can be obtained by one pseudo carrier generator. Since one power amplifier a plurality of pseudo carries signals, additional amplifiers need not being used.

Abstract: The present invention provides a system for efficient, high speed, high bandwidth, digital communication where transmit distances are greater than a single clock period. The digital system operates based on a system clock. Within the digital system a transmit module transmits data along with a capture clock signal to a receive module where the transmission time between the modules is greater than one period of the system clock. The capture clock operates in a known relationship to the system clock at a frequency at least twice as slow as the system clock. The digital system also has a synchronizing clock that operates at the same frequency as the forwarded clock. When the data arrives at the receive module it is captured by a pair of memory devices operating on different phases of the capture clock. The memory devices feed the data to a multiplexor that selects, as a function of the synchronizing clock, between the outputs of the two memory devices.

Abstract: A communication apparatus and a communication device that are selectively connectable to each other. A transmitter, associated with one of the communication apparatus and the communication device, transmits a first predetermined signal, such as, for example, an MS signal, to designate a specific mode to the other one of the communication apparatus and the communication device. The first predetermined signal includes an identification field that stores modulation independent information and a standard information field that stores modulation dependent information. A receiver receives a second predetermined signal, such as, for example, an ACK signal or a NACK signal, in response to the first predetermined signal from the other one of the communication apparatus and the communication device.

Abstract: A communication apparatus at a remote location is connectable to a communication apparatus at a central location. The apparatus includes a negotiation data transmitter that transmits negotiation data to the communication apparatus at the central location. The negotiation data includes an identification field that includes at least modulation independent information, a standard information field that includes at least modulation dependent information, and a non-standard information field that includes information other than information associated with the identification field and information associated with the standard information field.

Abstract: The system and method of the preferred embodiments may be directed to improving the signal-to-noise ratio in frequency spectrum regions where narrowband interference may be present. The system and method of the preferred embodiments includes reducing the narrowband interference by determining a noise estimate. In accordance with the noise estimate and output of a frequency domain equalizer, a noise-cancelled output may be obtained.

Abstract: A correlation method and a digital correlation device allowing detection of the occurrence of a coded reference sequence including N code elements or chips in a sampled reception signal are described. The reception signal is sampled at a frequency equal to d times the chip rate of the reference sequence, and d×Nd correlation values are generated for d×Nd successive delays of the reception signal, Nd being a lower number than the number N of chips. Each correlation value, for a given delay of the reception signal, is obtained, according to the present invention, at the end of a plurality of correlation operations during which partial correlation values covering code portions including Nd successive chips of the reference sequence are generated.

Abstract: To be able to transmit information at high bit rate in a domestic or industrial installation, it is planned to receive information at high bit rate sent by a remote sender unit to a specialized receiver. This specialized receiver playing the role of a network master is then provided with means to transmit this information by a carrier current channel made on the electrical network of the installation. In reception, a coupler is used to pick up this information from the electrical network. It is shown that, by acting in this way, it is possible to remove the need to make a specific infrastructure for this transmission at high bit rate, and that it is thus possible to enjoy the facility of having tapping points at all places since an electrical power supply network is generally distributed extensively in a building. Furthermore, several characteristics of modulation and transmission are chosen to withstand parasites and defects of transmission inherent in this type of network.

Abstract: A shared data and clock recovery circuit including a clock synthesizer for generating sampling signals having different phases, a multiple transition detector for receiving a data stream and sampling signals, and for detecting edges in a data stream in response to the sampling signals, a counter and accumulator for detecting the time occurrences and total number of edges, and for performing weighted average calculation to select one of the phases, a decision circuit for detecting the phase difference between a source clock and a local clock such that if the PPM difference between the source clock and the local clock is at least 200 PPM, then selection of a phase is based upon stored historical information, and if the PPM difference between the source clock and the local clock is less than 200 PPM, then selection of a phase is based on a weighted averaging calculation.

Abstract: A method of estimating the sequence of transmitted symbols in a digital communication system is provided. By assuming that the transmitted symbols have a zero mean and a covariance matrix given by an identity matrix, as is the case in an EDGE communication system, the solution to the minimization of the expectation value of ∥{circumflex over (s)}−s∥2 always allows a lower triangular matrix to be found through Cholesky decomposition. The lower triangular matrix allows an efficient block decision-feedback sequence estimation to be carried out. The method is no more complex than the zero-forcing block decision-feedback sequence estimation technique, yet a solution always exists and performance is improved over the zero-forcing method.

Abstract: With OFDM systems the frequency domain data is the Fourier transform of the received time domain OFDM frames. The time domain frames must be sampled, at the receiver, in synchronism with the transmitter, so that each received frame contains data from only a single transmitted frame. It is vital for this synchronism to be maintained in order to maintain the orthogonality of the frames. A typical multi-carrier system, of the OFDM type, which uses a cyclic prefix permits orthogonality to be maintained when there is a small deviation from exact frame synchronisation. Because the signalling interval includes both an entire frame and the cyclic prefix, which is a repetition of part of the frame, a frame sampled within the signalling interval will contain data from only one frame. Since the signalling interval is greater than the frame period, this gives some leeway in frame alignment. In a multi-carrier system of the OFDM type, an adaptive channel equalizer, operating in the frequency domain, is often used.

Abstract: A decision directed frequency detector and method for a quadrature amplitude modulated signal (QAM) demodulator. The demodulator interacts with a voltage controlled oscillator (VCO) that generates a carrier signal to demodulate the QAM signal into a baseband signal. The frequency detector determines the direction of rotation of the baseband signal by sampling the baseband signal relative to predetermined points in the phase plane. For example, if one sample has a negative phase offset with respect to a predetermined point and the next one has a positive phase offset, it detects that the rotation is clockwise, and vice-versa. A control signal is supplied to the VCO and the frequency of the carrier signal is adjusted to stop the rotation of the baseband signal.

Abstract: Symbol timing is performed by providing a histogram of samples of a signal for a predetermined number of symbol times. An average, weighted average, or other method is applied to determine an average timing for a max eye opening for each symbol time. The average max eye opening timing is applied to an edge detection of a currently received signal to determine timing of a sample that is most likely to occur closest to the max eye opening for the current symbol. The invention may also be practiced based on a center timing of each symbol.