Abstract: A digitizing analog front end (DAFE) using mixed technology on a single substrate is described. SiGe BiCMOS technology is implemented for the semiconductor components, which include a low noise amplifier and an analog-to-digital converter. Micro Electro Mechanical System (MEMS) switches are used to change the filtering characteristics of several filters, including an anti-aliasing filter and a pre-select and anti-jamming filter.

Abstract: A decision feedback structure for recovering a bit stream out of received signals is disclosed, wherein the sampling instant may be tuned in dependence of the sequence or pattern of the preceding bits so as to follow the bit sequence dependent instant of the maximum eye opening. The decision-feedback equalizer structure includes decision means for making a bit value decision at a sampling instant, a feedback path to feed back bit values to said decision means and means for adapting the sampling instant for a bit value decision made by said decision means with respect to the sampling phase depending on the bit values of preceding bits, in particular depending on the bit value of the previous bit.

Abstract: Disclosed is a real-time pulse sorting apparatus of a preprocessor in a pulsed radiation detection system. The apparatus, responsive to digital signals generated by a system receiver, uses the instantaneous frequency as the address input to store discrete data groups in main memory. Each data group, comprising the digital data corresponding to a single analog-to-digital converter sample point, includes the RF signal amplitude, inter-channel phase difference, instantaneous frequency as well as a unique pulse number generated by the pulse sorting apparatus. The present invention further includes a TOA memory for storing the time-of-arrival of each pulse at an address given by the pulse number. The main memory, organized in the form of a frequency-based histogram, together with the TOA memory, linked to the main memory by means of the pulse number pointer, sorts and records RF signal data with minimal processor control and intervention.

Abstract: A searcher uses an input signal, and for example, a matched filter to generate a first set of candidate paths. A selector uses the input signal and the first set of candidate paths to generate a second set of paths. The second set of paths is used to configure the fingers of a RAKE receiver. According to one aspect of the invention, the first set of candidate paths contains M paths, and the second stage uses M correlators to generate a set of M correlation values. The second stage uses the M correlation values to select N paths that are used to configure the N fingers of the RAKE receiver. According to another aspect of the invention, the first set of candidate paths contains M paths, and the second stage uses a multiple of M correlators to track the M paths and generate a set of M estimates. The second stage uses the M estimates to select N paths that are used to configure the N fingers of the RAKE receiver.

Abstract: A technique for utilizing spare bandwidth resulting from the use of a transition-limiting code in a multi-level signaling system is disclosed. In one particular exemplary embodiment, the technique may be realized as a method for utilizing spare bandwidth resulting from the use of a transition-limiting code in a multi-level signaling system, wherein the transition-limiting code has a characteristic wherein a signal level is periodically unused. Such a method may comprise modifying the transition-limiting code such that the periodically unused signal level is used to represent additional information.

Abstract: A technique for identifying the encoding law utilized by a central office codec may be implemented in a receive modem. The encoding law, which is typically dictated by the country in which the central office is located, is employed to generate a plurality of transmission levels during an initialization period associated with the modem system. The receive modem analyzes a number of these transmission levels to determine whether the levels have certain characteristics associated with the particular encoding law followed by the central office codec. When the receive modem detects the codec type, it may transmit a suitable identifier back to the transmit modem.

Abstract: A multi-level space time signal constellation that is optimized for use with a multi-carrier, multi-path communication scheme includes points on a first level separated from points on a mutually exclusive second level by a minimum distance that is based on a conditional probability distribution, preferably a Kullback-Leibler (KL) distance. Points within one level may be separated by a Euclidean distance, but spherical levels are rotated relative to one another to maximize a minimum inter-level KL distance. A receiver uses pilot symbols to estimate the channels and two-stage symbol detection, determining in one stage the constellation level and in another stage the point in the level. The receiver calculates a likelihood function based on a conditional distribution which does not reduce to the Euclidean-based nearest-neighbor detector. A single stored constellation may be scaled based on received signal to noise ratio.

Abstract: An ADSL transceiver hybrid circuit uses one or more isolated couplers (optical couplers, capacitors, or the like) configured to minimize the transmit signal component in the receive signal path by providing an isolated transmit signal feedback, thereby providing echo cancellation, isolating the telephone loop from the analog front end, and eliminating the need for a complex high-pass filter. The ADSL transceiver provides isolation and echo cancellation by: (a) generating a signal within the analog loop (e.g., telephone loop, or “local loop”) corresponding to a differential transmit signal; (b) receiving a composite signal from the analog loop corresponding to the sum of the transmit signal generated on the analog loop and the receive signal; (c) producing an isolated transmit signal (e.g.

Abstract: A method and apparatus are described for adaptively removing interference from a signal. A received signal is amplified linearly along a first signal path to provide a first signal and amplified nonlinearly along a second signal path to provide a second signal. The received signal propagates through the first and second signal paths at substantially the same time. The first and second amplified signals are mixed in proportion according to determined first and second weights, respectively, to provide an output signal having interference removed. The output signal is filtered to produce a first filtered signal corresponding to a ripple envelope of the output signal and filtered substantially simultaneously to produce a second filtered signal corresponding to an average peak detected value of the output signal. The first and second filtered signals are compared to produce an error signal. The first and second weights are determined according to the error signal.

Abstract: This invention generates pseudo-noise (PN) codes that map a transmitted data rate into the PN code structure. This invention further then acquires the PN code to automatically discover the transmitted data rate. This invention is operable with communication systems that utilize GPS time synchronization of the transmitted and received PN codes, as well as with communication systems where GPS time synchronization is not available. A method and a system are disclosed to transmit a modulated signal from a transmitter to a receiver, where the modulated signal has a data rate. The method includes selecting, to represent the data rate, at least one PN component code from a set of PN component codes. The PN component code is a constituent code of a composite PN code comprised of a plurality of PN component codes. The selected PN component code is one that phase aligns with a PN composite encoded signal.

Abstract: A GPS receiver having a ratio-based signal acquisition method. The GPS receiver has a tentative signal acquisition when a first ratio of the largest GPS signal correlation value to the second largest in a first time period exceeds a selected qualification ratio. The GPS receiver verifies signal acquisition when the average of iteration ratios for largest to second largest correlation values in iteration time periods exceed the qualification ratio.

Abstract: At the transmitter side, carrier waves are modulated according to an input signal for producing relevant signal points in a signal space diagram. The input signal is divided into, two, first and second, data streams. The signal points are divided into signal point groups to which data of the first data stream are assigned. Also, data of the second data stream are assigned to the signal points of each signal point group. A difference in the transmission error rate between first and second data streams is developed by shifting the signal points to other positions in the space diagram. At the receiver side, the first and/or second data streams can be reconstructed from a received signal. In TV broadcast service, a TV signal is divided by a transmitter into, low and high, frequency band components which are designated as a first and a second data stream respectively.

Abstract: The present invention relates in general to a method, apparatus, and article of manufacture for providing high-speed digital communications through a communications channel. In one aspect, the present invention employs a variable rate back channel, incorporated within an existing communication that does not increase or adversely impact the transmission rate of data on the communication channel.

Abstract: The present invention reduces adjacent channel interference for a wireless peripheral device. A direct digital synthesizer generates a waveform having intermediate angular changes during a transition time between symbol intervals. After the transition time, the direct digital synthesizer generates the waveform with an angular value that corresponds to the symbol being transmitted. In an exemplary embodiment, a generated waveform is characterized by one of two designated frequencies in response to a value of an input information bit. The waveform is further characterized by at least one intermediate frequency during a transition time between a change of the designated frequency. Another embodiment of the invention utilizes phase changes rather than frequency changes during reduce adjacent channel interference. With another aspect of the invention, methods are provided to determine waveform parameters for reducing adjacent channel power (ACP) to a maximum level of interference.

Abstract: The RF communications system of the present invention wirelessly communicates data without encountering undue interference problems with other devices and complies with rules governing unlicensed, spectrum-sharing devices. In an example embodiment, a transmitter device includes a digital subsystem powered by a power supply that processes data from another device and a radio frequency (RF) sub-system that transmits the processed data using a frequency hopping scheme. The RF sub-system includes a microprocessor arrangement that ON-OFF keys a voltage controlled oscillator (VCO) and provides a frequency-hopping scheme. The VCO is coupled to a signal frequency spreading arrangement that spreads the signal to a predetermined transmission bandwidth, wherein the frequency spreading occurs during an ON state of the ON-OFF keying and the transmission bandwidth exceeds a reception bandwidth at which the signal will be decoded.

Abstract: A method for detecting data symbols corrupted by intersymbol interference and timing error, comprises calculating a first plurality of state probabilities for received symbols using a forward recursive process on a joint intersymbol interference/timing error (ISI/TE) trellis, calculating a second plurality of state probabilities for the received symbols using a backward recursive process on the joint ISI/TE trellis, and using the first plurality of state probabilities and the second plurality of state probabilities to calculate a posteriori state transition probabilities for the received symbols. An apparatus that performs the method is also disclosed.

Abstract: A system for short range communications includes a transmitter capable of transmitting a colored noise-like preamble. A receiver receives the colored noise-like preamble and the receiver includes an antenna with an antenna pattern. A direction of the antenna is controllable by the receiver. A signal processor is connected to and responsive to the receiver. The signal processor detects and estimates the strength of the colored noise-like preamble.

Abstract: A system and method are provided for adjusting the phase output of a Hogge phase detector. The method comprises: using a Hogge phase detector, generating a reference signal; using the Hogge phase detector, generating a phase and reference signals; accepting an adjust signal; modifying the amplitude of the phase signal in response to the adjust signal; integrating the amplitude modified phase signal; using the integrated signal as a phase adjusted signal; integrating the reference signal; using the integrated reference signal and phase adjusted signal to generate a voltage controlled oscillator (VCO) signal; at the Hogge phase detector, accepting the VCO signal as the clock signal. Some aspects of the method further comprise: using the VCO signal to sample data at a settled first phase of the clock; changing the adjust signal; and, using the VCO signal to sample data at a settled second phase of the clock.

Abstract: Disclosed is a method and computer-readable medium for bit and power allocation for modems sharing a common multi-carrier binder, including Discrete Multi-Tone (DMT) based Digital Subscriber Line (DSL) modems. In one preferred embodiment, the method includes the steps of initializing a modem by calculating loop-to-loop channel transfer functions and noise power spectral densities (PSDs) at a corresponding receiver, and taking into account cross-talk between loops in the process of allocation so as to maximize total data rates within the binder.

Abstract: When once determined to be free of any demodulation error by an interference removing unit provided user by user, a replica signal calculated by the interference removing unit is subtracted from an input signal vector, and a calculated user signal is output as it is as a final user signal. When it is determined by the interference removing unit that there is a demodulation error, the user signal is again calculated by the interference removing unit of an interference canceller of a next stage. As subtraction of the replica signal corresponding to the user signal having a demodulation error from the input signal vector is inhibited, precision of the interference wave removal can be improved.