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7630290 Interference suppressing OFDM system for wireless communications  
An IS-OFDM system for point-to-point wireless communications that suppresses narrow-band interference comprises an IS-OFDM transmitter and an IS-OFDM receiver, wherein a transmitted signal...
7606321 System and method for simplifying analog processing in a transmitter incorporating a randomization circuit  
The system and method enable simpler analog processing in a transmitter by reducing the number of bits in a digital signal through delta sigma modulation. Selection of current sources in a digital...
7515645 Method for dividing the bit rate of QPSK signals into two or several subchannels  
The invention relates to a method for dividing the bit rate of QPSK signals by splitting the spectrum of said QPSK signals into at least two channels having band-limited filters in the modulator...
7426246 Dual layer signal processing in a layered modulation digital signal system  
Systems and methods for receiving layered modulation for digital signals are presented. An exemplary apparatus comprises a tuner for receiving a layered signal and producing a layered in-phase...
7412006 Method and apparatus for RF carrier feedthrough suppression  
A method includes performing a search method to determine a pair of receiver path correction signals, performing the search method to determine a pair of transmitter path correction signals, and...
7409012 Modulator and signaling method  
Phase shift key modulators ( 100, 500, 1000, 1400, 1700 ) are provided in which a multiphase signal source ( 108, 1402, 1406 - 1412,1702 ) is used to generate a plurality of phases of a carrier...
7356089 Phase offset spatial multiplexing  
A rotation by a phase offset is applied to symbols to be transmitted by one antenna relative to symbols to be transmitted from another antenna in a wireless communication system employing...
7319716 Transmitter image suppression in TDD transceivers  
In a transceiver comprising a time-division-duplex (TDD) of transmit and receive functions, the characteristics of unwanted image signal energy being transmitted from the transceiver are...
RE39983 Carrier injecting waveform-based modulation scheme for reducing satellite transponder power requirements and earth terminal antenna size  
A QPSK modulation scheme uses a data spreading mechanism to rob a relatively limited portion of available transmitter power, and inject into the QPSK waveform a prescribed amount of carrier signal...
7305042 T1 radio having coding gain adjustable for number of channels  
A communication system for transmitting (T 1 ) digital communication signals between a transmit site and a receiver site includes an M:1 multiplexer, coupled to a rate 1/N convolutional encoder,...
7260159 Method and apparatus for providing higher order modulation that is backwards compatible with quaternary phase shift keying (QPSK) or offset quaternary phase shift keying (OQPSK)  
A method and apparatus for providing an asymmetrical backwards compatible communications signal that is capable of being decoded by QPSK and OQPSK receivers as well as PSK and QAM receivers is...
7206417 Wireless digital transmission system for loudspeakers  
This invention relates to a wireless digital transmission system for loudspeakers comprising: compression means for the file representing the digital audio signal of the “compact disc”...
7062228 Cellular communications system using baseband carrier injection and related methods  
A cellular communications system may include one or more cellular base stations and a plurality of mobile cellular communications devices for communicating therewith. More particularly, the...
7057538 1/N-rate encoder circuit topology  
An encoder circuit and a related method for its operation, in which digital encoding, such as differential phase-shift keyed (DPSK) encoding, is performed as a parallel operation on N bits at a...
7016425 Quasi-differential modulation/demodulation method for multi-amplitude digital modulated signals and OFDM system  
The invention proposes the separate processing of the phase and amplitude of multi-amplitude digital modulation techniques, such as a QAM. The phases are differentially modulated and the amplitudes...
6973141 Flexible multimode QAM modulator  
A method of baseband/passband digital modulation for a data transmission system wherein a plurality of data symbols is transmitted over a transmission channel at a symbol rate. The method comprises...
6836484 Wireless packet communication method and system for transmitting packets between base station and radio terminal station  
A wireless packet communication system includes at least one radio terminal station, and a base station for multiplexing packets to be transmitted using a plurality of subcarriers and for sending...
6763072 Method and apparatus for modulation and demodulation related to orthogonal frequency division multiplexing  
Data pieces representative of in-phase components and quadrature components of a digital-modulation-resultant signal are assigned to frequencies for inverse fast Fourier transform. The inverse fast...
6707860 DC offset correction for direct-conversion receiver  
A method and offset removing apparatus for removing DC offset from a digital baseband signal value pair included in a set of digital baseband signal value pairs is described. The digital baseband...
6690945 Method for suppressing transients using a pulse shaping look-up table  
The pulse-shaping look-up table with transient suppression ( 530 ) avoids hard turn-on and turn-off transients by modifying word segments of initial and final digital words during transmission of a...
6683917 Base band signal processing circuit capable of improving both noise characteristic and distortion characteristic  
The base band signal processing circuit of the present invention intends to improve both the noise characteristic and the distortion characteristic, and moreover set both the characteristics in a...
6628727 Apparatus and method for performing &pgr /4-DQPSK baseband modulation based on a signal mapping to be simplified  
The present invention is an apparatus and method for performing a π/4-DQPSK baseband modulation based on a signal mapping to be simplified. The apparatus mainly comprises a memory unit and as...
6621426 Method and apparatus for modulating a signal  
A modulated signal ( 10 ) is sinusoidal wave signal wherein each half wave cycle carries a digital data value associated with an amount of its amplitude. A positive half wave cycle with an...
6594320 Orthogonal Frequency Division Multiplexed (OFDM) carrier acquisition method  
In all wireless systems, the first operation that must take place at the receiver is the acquisition of the carrier and timing. OFDM systems are particularly sensitive to carrier offsets since...
6590945 Method and apparatus for frequency offset compensation  
A simplified method for frequency offset estimation in a TDMA cellular PCS environment using π/4-shifted DQPSK comprises the steps of multiplying a complex conjugate of a received complex-valued...
6496542 Digital communication system  
Disclosed is a digital communication system for mobile communication, which has: a transmitter for mixing and outputting outputs from two independent and equivalently synchronized transmitting...
6477153 Method and apparatus for using the sidelobe of a long range antenna for a short range communication link  
A communication satellite system ( 100 ) is established using one or more satellite constellations ( 110, 120 ). The two or more satellite groups ( 110, 120 ) are connected via long range...
6470056 Offset QPSK modulation analytic system  
The offset QPSK modulation analytic system capable of estimating the initial phase of an offset QPSK modulated signal is disclosed. For each of a plurality of candidate values for the initial...
6445746 IS-136&plus slot formation  
A system and method for demodulating slots having a mixed slot formation including differential and coherently encoded slots is disclosed. The method includes pre-phase encoding data and a...
6445745 Phase encoding methods for handling multiple phase modulated signals on a single channel  
A method for phase encoding DPSK and N-PSK which maintains phase continuity and which does not require any reference symbols when using N-PSK. A sequence of known DPSK phases are encoded with...
6366622 Apparatus and method for wireless communications  
An apparatus for receiving signals includes a low noise amplifier (LNA) configured to receive a radio frequency (RF) signal. An I/Q direct down converter is coupled to the LNA. The I/Q direct down...
6351503 Threshold extension block phase estimator for quasi-coherent communications systems  
The invention relates to a threshold extension block phase estimator (TEBPE) which estimates phase in the presence of noise. Threshold and sector slips are controlled by an iterative calculation....
6301291 Pilot symbol assisted modulation and demodulation in wireless communication systems  
A transmitter which includes a quadrature phase shift keying (QPSK) modulator, and a receiver which includes a pilot correlation filter (PCF), a data matching filter (DMF), a timing recovery...
6285721 Method for assisting simple synchronization to the carrier of a dispersed-energy QPSK signal  
A method for simple synchronization of a receiving device to a transmitting device for a transmission of a dispersed-energy QPSK signal. The signal is composed at the transmitting end of two mixed...
6243427 Multichannel radio frequency transmission system to deliver wideband digital data into independent sectorized service areas  
A one-way and two-way multichannel radio frequency transmission system and method employing a sectorized broadcasting technique is described. The system and method reduces the effective bandwidth...
6222878 Communication system with end-to-end quadrature balance control  
A communication system (10) includes a transmitter (20) having programmable signals (46, 58, 60, 80) which can be used to adjust transmitter-caused quadrature-phase signal imbalances. A receiver...
6157679 Method of adding encryption/encoding element to the modulation/demodulation process  
A method is provided of adding an encryption element to the QAM modulation/demodulation process. This is achieved by first forming a sequence of transmit QAM constellation symbols on the basis of...
6125148 Method for demodulating information in a communication system that supports multiple modulation schemes  
A method of demodulating voice or data and control information in systems that support multiple modulation schemes modulates voice or data using a first linear modulation scheme, such as 16QAM...
5999570 Transmission apparatus, sending apparatus, and receiving apparatus, and transmission method  
The transmitter QPSK-modulates the audio data, generates a transmission channel clock having a frequency 5/4 times the data clock based on the audio data, and outputs the modulated signal resulted...
5987068 Method and apparatus for enhanced communication capability while maintaining standard channel modulation compatibility  
In a radio communication system (100), enhanced communication capability is provided while maintaining standard channel modulation compatibility. At a transmitter (110, 200, 600), a first...
5933448 Automatic tuning of a radio transceiver  
Amplitude and phase errors between branches I and Q of a transceiver utilizing phase quadrature modulation are corrected by preventing propagation of a nominal-frequency signal from a digital part...
5930299 Digital modulator with compensation and method therefor  
In a digital modulator with compensation, a digital bit stream from a microphone (705), a speech coder (706), and a channel encoder (707) is sent to an encoder (720) which translates the bits into...
5847622 Quadrature phase shift keying modulating apparatus  
A quadrature phase shift keying (QPSK) modulating apparatus includes a bit splitter for dividing a bipolar input bit stream into first and second data streams, first and second binary phase shift...
5832044 Transmitter antenna diversity and fading-resistant modulation for wireless communication systems  
The present invention provides a bandwidth-efficient fading-resistant transmission scheme where a base station implements transmitter diversity using L antennas or L carrier frequencies or L time...
5673291 Simultaneous demodulation and decoding of a digitally modulated radio signal using known symbols  
Systems and methods according to the present invention provide a combination of demodulation and decoding, termed decodulation herein. By using knowledge of known symbols, decoding known symbols...
5668795 Modulation system for spread spectrum CDMA communiction  
The OCDMA waveform of the present invention uses bi-phase PN modulation (BPSK PN chip modulation) in conjunction with MPSK or MQASK data modulation (QPSK data modulation is one preferred...
5661757 Radio-card communication system  
To receive a response signal from a radio card, a card reader transmits a carrier (not modulated) to the radio card. In the radio card, a phase modulator phase-modulates the a sub-carrier with a...
5615230 Process for transmitting digital signals which combines advantages of OQPSK and π/4-QPSK  
A process for transmitting digital signals, in which the digital data are coded differentially in symbols of a symbol period T s (2.1, 2.2), the symbols transmitted with the Q component being...
5604770 PI/4 DQPSK modulation with coarse mapper precession and fine filter precession  
The amount of memory needed for a ROM-based π/4 DQPSK filter is reduced by using a mapper in an IQ modulator (inverse mapper in a demodulator) that incorporates a 90° phase shift for every other...
5602669 Digital signal transmission apparatus, digital signal transmission method, and digital signal transmitter-receiver  
A digital signal transmitting apparatus, a digital signal transmitting method, and a digital signal transmitter-receiver, for transmitting a digital signal within a specified frequency band by...
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