A power line communication (PLC) apparatus wherein transmission mode information is encoded into each data packet while maintaining immunity from single bit errors. In the present invention, a power line communication system includes a transmitter/receiver (i.e. transceiver) which is coupled to a power distribution network. Data is transmitted through the power line by the transceiver in packets. The transceiver includes a preamble generator which creates a preamble for each of the data packets and a preamble decoder that decodes the preamble of a data packet and determines word sync for the packet. The preamble generated by the preamble generator consists of a carrier detect interval, a carrier sync interval, a bit sync interval, and a word sync pattern. The transceiver may select either BPSK or QPSK transmission modes on a data packet by data packet basis by encoding information into the packet preamble. Transmission mode information is encoded into the preamble using one of two seven-bit cross compatible word sync patterns for each data packet. Thus, one word sync pattern is used to define a BPSK transmission while the other word sync pattern is used to define a QPSK transmission. The transmitter may send data packets using either BPSK or QPSK on a packet by packet basis by generating the appropriate word sync pattern for each packet. The receiver uses the word sync pattern to determine the receive mode for each packet.

Transmission mode detection in a modulated communication system

Dual Carrier Modulator (DCM) for a Multiband OFDM (Orthogonal Frequency Division Multiplexing) Transceiver of a Ultra Wide Band (UWB) wireless personal access network transmitting OFDM modulated symbols, wherein each OFDM symbol is modulated by a predetermined number (N CBPS) of encoded bits, said Dual Carrier Modulator (1) comprising: (g) a grouping unit (1-1) for grouping NCBPS encoded bits of a serial bit stream into bit groups each having a predetermined number (m) of bits; (h) a mapping unit (1-2) for mapping each bit group received from said grouping unit to complex symbols(y) using an orthogonal transform; and (i) a reordering unit (1-3) for reordering the complex symbols (y) mapped by said mapping unit, wherein each complex symbol (y) is provided to modulate a corresponding data tone of an OFDM symbol.

Dual carrier modulator for a multiband OFDM transceiver

In the transmitter which carries out burst transmission using information data as a packet, if the status is divided into four modes, namely, burst stop mode, burst rising mode, burst continuous mode, and burst falling mode, a waveform shaping equipment designed to read out shaped waveform data for each mode from outputs of either of the two memory tables, the first memory table which holds waveform data for specific data patterns used in common in burst rising mode and burst falling mode and the second memory table which holds waveform data for all data patterns used in the burst continuous mode, or a waveform shaping equipment comprising the third memory table which holds waveform data corresponding to all the data patterns used in the burst rising mode and the fourth memory table which holds waveform data corresponding to all data patterns used in the burst falling mode and generating shaped waveform data by synthesizing the two outputs of the third and the fourth memory tables at the time of burst continuous mode.

Waveform shaping method and equipment

A transmission apparatus includes a frame configuration determiner that determines a modulation system from among a plurality of modulation systems on a communication situation. A first symbol generator modulates a digital transmission signal according to the modulation system determined by the frame configuration determiner and generates a first symbol, the first symbol comprising a first quadrature baseband signal. A second symbol generator modulates the digital transmission signal according to a predetermined modulation system and generates a second symbol, the second symbol comprising a second quadrature baseband signal.

Transmission apparatus, reception apparatus and digital radio communication method

A system and method is provided for transmitting data signals and additional information signals having partially overlapping frequency bands simultaneously within a wire based communication system over the same wired medium using a spread spectrum technique for modulating the additional information signals.

System and method for transmitting data and additional information simultaneously within a wire based communication system

A modulator for generating a burst-like modulated wave used in a multi-carrier transmission type communication system in which a plurality of modulated waves including at least one burst-like modulated wave exist on the same transmission line and the frequency band occupied by energy of each of the plurality of modulated waves is limited. Polarities of the transmission code which appear before and after either of on-timing and off-timing of the carrier on/off switched to obtain the burst-like modulated wave among the plurality of modulated waves are inverted to each other, whereby the envelope of the burst-like modulated wve can be changed gradually at the carrier on/off timing in order to reduce the interference of the modulated wave with the adjacent channels without degrading the transmission efficiency.

Modulator for generating a burst-like modulated wave

A digitized quadrature phase shift keying modulator capable of making the modulation output frequency variable and sufficing a single ROM of waveform shaping digital filter with look-up table by using interpolators which re-sample waveforms of impulse response of each of the output I data and Q data from the digital filter to change the sampling rate and extractors for extracting the interpolated I data and Q data so that samples of each of the interpolated I data and Q data occur sequentially and alternately at different timings.

Digitized quadrature phase shift keying modulator

PURPOSE: To decrease the effect onto an adjacent channel by setting a code before and after the timing of a modulation wave to be subject to ON/OFF into opposite polarity in applying ON/OFF control to the modulated wave adopting the digital modulation system among plural modulation waves. CONSTITUTION: A binary I code string 23 and a binary Q code string 24 from a frame format generating circuit 1 of a burst modulation wave are added by an adder 8 and outputted via inverting code insertion circuits 13, 14, NRZ waveform converting circuit 2, 3, band limit filters 4, 5 and double balanced mixers 6, 7 respectively. An inverting code insertion timing control circuit 15 controls inversion code insertion circuits 13, 14 to set the code before and after the timing subject to ON/OFF for the modulation wave is set to opposite polarity. COPYRIGHT: (C)1988,JPO&Japio

Kazuo Yagi

Papers

Modulator for generating a burst-like modulated wave

Digitized quadrature phase shift keying modulator

Carrier on/off system