933 results about "Phase-shift keying" patented technology

A method and system for increasing data rate in a mobile terminal using spatial multiplexing for digital video broadcasting for handhelds (DVB-H) communication are provided. A reconfigurable orthogonal frequency division multiplexing (OFDM) chip may be utilized in a mobile terminal to process received spatially multiplexed signals. The mobile terminal may be utilized in a spatially multiplexed multiple-input-multiple-output (SM-MIMO) wireless system. The spatially multiplexed signals may be quadrature phase shift keying (QPSK) modulated and may utilize OFDM subcarries. A processor may be utilized to configure the OFDM chip to process signals such as IEEE 802.11 and 802.16, and DVB. The OFDM chip may generate channel weights to be applied to the spatially multiplexed signals received in multiple receive antennas. The weighted signals may be combined to generate multiple RF received signals from which channel estimates may be generated. Subsequent channel weights may be dynamically generated from generated channel estimates.

The present invention is directed to a system and method of remotely controlling a welding machine with command signals transmitted to the welding power source across a weld cable connecting the power source to a remote device, such a wire feeder. A transmitter transmits the control commands containing desired welding operational parameters to a receiver disposed in the power source across a weld cable also designed to carry welding power from the power source to the wire feeder.

A demodulator used in a base band processor of the spread spectrum radio transceiver includes a demodulator circuit for spread spectrum phase shift keying (PSK) demodulating an information signal received from a radio circuit. The information signal includes data symbols formed from a plurality of high rate mode chips forming a spread spectrum information signal. At least one predetermined code function correlator is in line with a signal input for decoding the information signal according to a predetermined code. A carrier loop circuit allows phase and frequency tracking of the information signal and a chip decision circuit is operative with the carrier loop circuit for tracking high rate mode chips. A decision feedback equalizer formed from a feedback finite impulse response filter is operative with the chip decision circuit and the carrier loop circuit. It has a plurality of feedback taps. At least one feedback tap is selected for logical add / subtract operations to aid in canceling multipath signal echoes. A feed forward finite impulse response filter can also be positioned in line to the code function correlator and the signal input and has a plurality of feed forward taps that are selected for logical multiply operations to aid in reducing multipath signal echoes. A method aspect of the invention is also disclosed.

An approach is provided for generating Low Density Parity Check (LDPC) codes. An LDPC encoder generates a short LDPC code by shortening longer mother codes. The short LDPC code has an outer Bose Chaudhuri Hocquenghem (BCH) code. According to another aspect, for an LDPC code with code rate of 3 / 5 utilizing 8-PSK (Phase Shift Keying) modulation, an interleaver provides for interleaving bits of the output LDPC code by serially writing data associated with the LDPC code column-wise into a table and reading the data row-wise from right to left. The above approach has particular application in digital video broadcast services over satellite.

A method and apparatus for transmitting and receiving convolutionally coded data in a communication system employing a combination of Pulse Position Modulation (PPM) and Binary Phase Shift Keying (BPSK), wherein the code is selected to have error rate performance that is as good as the best convolutional code used with systems employing only BPSK.

A method and apparatus for transmitting uplink acknowledge information (ACK) in a communication system using an orthogonal frequency division multiple access (OFDMA) scheme. The method includes receiving a data bit for the uplink ACK; outputting codewords corresponding to the data bit; performing quadrature phase shift keying (QPSK) modulation on symbols for ACK vector indexes corresponding to the codewords for the received data bit; performing inverse fast Fourier transform (IFFT) on a transmission signal having subcarrier clusters to which the modulated transmission symbols are allocated; and transmitting the IFFT-processed transmission signal.

The present invention involves a method and system for transmitting two levels of data in a hierarchical transmission schema. A first modulated signal is generated based on first input. A second modulation signal is generated based on a second input that has a data rate that is a fraction of the data rate of the first modulated signal. The second modulation signal has known instances where the second modulation signal has no energy. In a system where the first modulation is quadrature phase shift keying (QPSK), the second modulation signal can be a secondary phase offset. A receiver in the system that has a priori knowledge about the timing relationship between the first data signal and the instances when the second data signal is present will be able to detect both data signals optimally.