Abstract: A wireless communication system containing at least one transmission apparatus and at least one communication terminal. The transmission apparatus transmits a wireless signal representing a bit sequence containing at least a predetermined number of bit errors, to the communication terminal. The communication terminal receives the wireless signal to regenerate the bit sequence. The communication terminal then examines the bit sequence represented by a received wireless signal to determine whether or not the number of bit errors contained in the bit sequence is equal to or greater than a predetermined number. When it is determined that at least the predetermined number of bit errors are contained in the bit sequence represented by a received wireless signal, the operation of the communication terminal is made inactive.

Abstract: The present invention relates to a CDMA system, which, in part, uses serial and parallel interference cancellation methods to overcome disadvantages of a method of detecting single user, and comprises a feedback loops for providing reproduced signals to respective inputs of detectors, and a means for controlling an operation for the detectors to attribute to interference cancellation process. The detectors to contribute to interference cancellation process can be also selected group by group. It is used to switch off only detectors contributing to interference cancellation process in progress and detectors contributing to previous interference cancellation, providing a adaptive serial and parallel mixed interference cancellation method for increasing performance and capacity of the CDMA system.

Abstract: A method and apparatus of synchronizing a serial bus data rate to a serial bus function data rate to eliminate the build up of overruns or underruns of data. A response is provided to a start of frame packet. The response packet contains a response code for indicating a modification to the serial bus frame counter. Thereby, slight variations in data rates can be eliminated by adjusting the serial bus data rate instead of the serial bus function data rate.

Abstract: Communication links are quickly and reliably established between units of a cordless telephone configured for operating in a frequency hopping system. This is achieved through specific processes which detects frequency hopping patterns that are embedded in radio frequency noise. A first process is executed by the base unit and/or each of multiple handset units in the cordless telephone for performing a link acquisition with another unit, also in the cordless telephone. In the execution of this process, multiple profile scans of the frequency hopping channels are executed to build up over time tables with information about energy in all of the channels in the frequency spectrum that are used by the units in the cordless telephone for frequency hopping. In the tables will be spectrum energy from a frequency hopping base unit or handset unit that appears as a recognizable pattern.

Abstract: An error correction circuit compensates for baseline wander which can occur when a data signal is passed through a DC isolation stage. The data signal, and its inverse are compared with a common reference level, and the error signal modifies the charge on a capacitor which forms part of a pair of negative feedback loop to control the baseline level.

Abstract: A mobile radio apparatus includes a base station and a mobile station which communicate with each other by a hybrid code division multiple access scheme. The base station selects a hopping pattern in a frequency hopping method so as to completely avoid overlapping of a carrier for a forward link signal with a carrier for a reverse link signal at the same time, and transmits the forward link signal in a predetermined frequency band. The mobile station similarly transmits the reverse link signal.

Abstract: The invention relates to a digital transmission system having a receiver which includes an equalizer for estimating transmitted binary symbols, from a sequence of sample values (6) of a received signal distorted by a transmission channel, by a reduced-state sequence estimation method or a reduced-state single symbol estimation method (11). To provide a receiver featuring high reliability combined with a clear state reduction of the estimation method, a minimum-phase substitute system (14) distorts the sample values received after received after a known training sequence (27) in the sequence of sample values (6)in the received order, and a maximum-phase substitute system (14) distorts the sample values (6) received before a known training sequence (27) and to be processed in reverse order for forming an estimate (11) for a received signal. The number coefficients of the impulse response which are reduced by the state reduction and used for the estimation, render the estimation inaccurate.

Abstract: Since output voltage e of coupler CU2 is displaced in phase by -135 degrees from input signals c and d (by -270 degrees from signals a and b), a carrier which makes signal f is phase shifted by -270 degrees by phase shifter .phi.1 so that signal f may have the same phase as signal e. Signal f and signal e are power composed by first 3 dB coupler M1, and are further phase shift controlled by variable phase shifters PH11 and PH12 so that they may have the same phase. Further, an output signal of variable phase shifter PH11 is phase shifted by -90 degrees by phase shifter SH1 so that it has a phase difference by 90 degrees from an output signal of variable phase shifter PH2, and the two signals controlled in this manner are inputted to 3 dB coupler M2. Consequently, two signals e and f inputted to the amplifier are all outputted as output voltage EOUT.

Abstract: The invention is a receiver front end for a data communications system having adaptive correction for intersymbol interference, DC offset, baseline wander, and flat loss and related method. Each of the compensation circuits is adaptive and is controlled by adaptation logic via a digital feedback loop including a digital integrator for providing perfect or near-perfect integration of the adaptation algorithm feedback error signal. The architecture further utilizes multiple comparators, including continuous-time and clocked comparators, for separately detecting various aspects of the received data signals that are used to determine the signal degradation characteristics needed to generate error signals for the adaptation feedback loops.

Abstract: An inexpensive, compact digital radio receiver corrects IQ imbalance, non-orthogonal I and Q phases, and DC offset by a DSP. The digital radio receiver is equipped with an antenna, an RF/IF converter for converting a radio frequency into an intermediate frequency, an IQ separator for separating I and Q, a filter for eliminating a noise such as a radio frequency, a multiplying sampler for sampling the output of the filter, and a digital signal processing unit mainly comprised of the DSP which implements an algorithm for estimating and correcting an IQ distortion and also performs quadrature phase demodulation. The IQ distortion can be removed inexpensively by making use of a part of a standard radio operation, hardly requiring the use of hardware for adjustment.

Abstract: A system and method for controlling the time occupation of signalling frequencies is disclosed, in a frequency hopping system including a plurality of remote stations communicating under control of transceivers with a transceiver of a base station, such communication being performed over a shared medium through a sequence of frequency hopping periods in a plurality of operating frequencies. The method consists in selecting a set of signalling frequencies among the operating frequencies, and interleaving signalling messages transmitted on each signalling frequency within each frequency hopping period to allow a remote station to enter the network for the first time or by re-acquiring synchronization, by scanning each signalling frequency for receiving a signalling message.

Abstract: A displacement detecting apparatus outputs a displacement information signal obtained by interpolating a phase modulation. A direction block obtains a direction signal indicative whether the cycle of the phase modulation signal is longer than the cycle of the reference signal. A phase difference block obtains the number of the interpolation clock pulses which number corresponds to a phase difference between the phase modulation signal and the reference signal. An up/down counter counts to an interpolation number upon receiving the direction signal and a pulse train corresponding to the phase difference. The presetting block presets the number of pulses corresponding to the phase difference in the up/down counter. The displacement information block outputs a Glay code converted from continuous 2 bits of the count value of the up/down counter as displacement information.

Abstract: To control the oscillation frequency of a local oscillator, a digital broadcast receiver demodulates a phase-reference symbol contained in an orthogonal frequency-division multiplexed broadcast signal, modifies the resulting frequency-domain data by multiplication with complex conjugates of known data encoded in the phase-reference signal, under different assumed frequency offsets, converts the modified data to time-domain data, and thereby detects a first frequency error equal to a multiple of the subcarrier spacing and a second frequency error not exceeding the subcarrier spacing. Differential phase error is also detected. The oscillation frequency is adjusted to correct the first frequency error and differential phase error; then the second frequency error is used to correct for ambiguity in the differential phase error.

Abstract: An improved method and apparatus for effecting code synchronization in a global positioning system receiver is disclosed herein. Within the receiver, digital in-phase (I) and quadrature (Q) samples of a plurality of received pseudorandom noise (PRN) encoded signals are provided to a code synchronization circuit. The code synchronization circuit is designed for coherent-mode operation when the receiver has achieved phase-lock with one of the PRN encoded signals, and operates in a non-coherent mode otherwise.The code synchronization circuit includes an I-channel correlator for producing a coherent-mode discrimination signal by correlating in-phase (I) samples of a first of said PRN encoded signals with a discrimination pattern, wherein the first PRN encoded signal is encoded with a first PRN code.

Abstract: To control the oscillation frequency of a local oscillator, a digital broadcast receiver demodulates a phase-reference symbol contained in an orthogonal frequency-division multiplexed broadcast signal. The resulting frequency-domain data are modified by multiplication with complex conjugates of the known data encoded in the phase-reference signal, under different assumed frequency offsets between the frequency-domain data and known data. The results are converted to time-domain data, yielding one time series for each assumed frequency offset. One value is taken from each time series, these values are compared, and the oscillation frequency is adjusted according to the comparison results.

Abstract: A digital radio communication system includes a first down converter for converting down a predetermined radio frequency (RF) signal into a first intermediate frequency (IF) signal according to a first local oscillation signal; a second down converter for converting down the first IF signal into a second IF signal according to a second local oscillation signal; a demodulator for demodulating the second IF signal according to a third local oscillation signal and outputting a predetermined base band of a signal; a modulator for modulating the predetermined base band of signal according to the second local oscillation signal and outputting a third IF signal; a up converter for converting the third IF signal to a RF signal according to the first local oscillation signal; a first phase-locked loop (PLL) for controlling the first local oscillation signal in a direction where the sum of the frequency deviation between the first local oscillation signal and a reference frequency signal and the frequency deviation bet

Abstract: A frequency-hopped mobile communication system is disclosed, in which a mobile wireless station automatically becomes a base station in accordance with the surrounding conditions, thereby automatically reconfiguring a communication network. A control frame is generated by at least one master station, and frequencies are hopped by a plurality of slave stations in accordance with the control frame. Each slave station switches the master thereof to be tracked, in accordance with the receiving conditions of the control frame and the relation between the control frame received from the master station and the status of the slave station and decides in which mode, master station or slave station, the slave station is to operate. The cells are thus automatically reconfigured.

Abstract: A system for transmitting information from a source to a destination using multilevel signaling. Multiple conductors are coupled between the transmission source and the transmission destination. Multiple drivers are coupled to the conductors at the transmission source. Each driver is coupled to a pair of conductors. Multiple comparators are coupled to the conductors at the transmission destination. Each comparator is coupled to a pair of conductors. The information is encoded into a sequence of symbols in which each symbol represents a unique permutation of signal levels on the conductors. Each signal level is used at least once for each symbol. All signal levels associated with a particular symbol are transmitted over the conductors simultaneously.

Abstract: The disclosure presents a number of reduced complexity architectures for despreading direct sequence spread spectrum communications signals. In a first despreading architecture for a sequence removal unit, received chip-spaced complex samples are negated in accordance with the processed phase of a complex spreading sequence. Furthermore, the in-phase and quadrature phase sample values are switched for each other in accordance with the processed phase. In a second despreading architecture, in a sequence removal unit, received chip-spaced complex samples are processed in the logarithmic domain, with the phase of the complex spreading sequence added to the detected phase, and the resulting complex signal then converted back to Cartesian coordinates. In a third despreading architecture for a correlator, sequence removal and correlation are performed in the logarithmic domain with the amplitudes and phases for the resulting complex signal arithmetically averaged and then converted back to Cartesian coordinates.

Abstract: An adaptive equalization filter system and method [including a controllable equalization filter] which filters a signal received over a transmission link in response to feedback indicative of channel characteristics. The system uses closed loop feedback to control [the] an equalization filter to achieve cancellation of each pole of the channel transfer function with a zero of the equalization filter, by moving the zero of the filter in response to feedback indicative of the difference in transmission delay between received and equalized high and low frequency signals (e.g., high and low transition density portions of a received and equalized data signal, or received and equalized high and low frequency clocks transmitted over the channel in parallel with a data signal) until the feedback indicates equal delays for the two equalized signals. In some embodiments, phase comparison is performed on clocks recovered from high and low transition density portions of a received and equalized data signal.