Abstract: A transmitting system wherein a transmission signal composed of main data and a TMCC signal having a SYNC pattern indicating the header portion and a bit pattern indicating setting information of the main data is transmitted and received. In the transmitting apparatus, the reference timing for starting the input data scramble process is rendered to coincide substantially with the modulation timing for modulating the scrambled data and generating the main data, and the modulation timing is rendered to coincide substantially with the timing for generating the TMCC signal thereby to generate the TMCC signal. From the transmission signal, the receiving apparatus demodulates the main data, extracts the SYNC pattern indicating the header portion from the TMCC signal and inversely scrambles the main data based on the extracted SYNC pattern.

Abstract: A transmission apparatus of orthogonal frequency division multiplexing for multiplexing a plurality of carriers orthogonal to one another to transmit a modulated signal. The transmission apparatus includes a first modulator for outputting a code modulated in accordance a modulation scheme which can be applied with a synchronous detection for demodulation, a second modulator for outputting a code modulated in accordance with a modulation scheme different from the modulation scheme associated with the first modulator, and a distributing circuit for distributing the codes modulated by the first and second modulators to a plurality of carriers. The distributing circuit distributes the code modulated by the second modulator to all or some of carriers existing within a predetermined number of columns from at least one of both end regions of a signal transmission frequency band, and the code modulated by the first modulator to the remaining carriers.

Abstract: A signal transmission apparatus for a digital modulation type, wherein each of information codes is assigned to any one of a plurality of signal points arranged on an I-Q complex plane, a pilot signal used for demodulating said information codes and an auxiliary signal are assigned to be arranged on signals points on the I-Q complex plane, a signal modulated based on coordinates corresponding to the assigned signal points is transmitted, the transmitted signal is received, and the received signal is demodulated to reproduce the information codes, and wherein the signal points of said auxiliary signal and said pilot signal are arranged on different positions on said I-Q complex plane.

Abstract: An encoder and a decoder each having an error correcting operation, and a data transmission apparatus using them for data transmission in a multilevel modulation system. In transmission data is converted into parallel data. One bit thereof is inputted to a convolutional encoder to output two bits. Two bit data and another signal of the parallel data not inputted to the convolutional encoder are respectively separated into real part and imaginary part to independently decide signal points for the parallel data. In reception an area is similarly decided independently for real and imaginary parts and metric is assigned for the data. Real and imaginary parts are combined with each other for Viterbi decoding. Result thereof is fed to a convolutional encoder similar in constitution to that on transmission side. Using convolutional encoding output and decided area, transmission data is decoded.

Abstract: A transmitting system wherein a transmission signal composed of main data and a TMCC signal having a SYNC pattern indicating the header portion and a bit pattern indicating setting information of the main data is transmitted and received. In the transmitting apparatus, the reference timing for starting the input data scramble process is rendered to coincide substantially with the modulation timing for modulating the scrambled data and generating the main data, and the modulation timing is rendered to coincide substantially with the timing for generating the TMCC signal thereby to generate the TMCC signal. From the transmission signal, the receiving apparatus demodulates the main data, extracts the SYNC pattern indicating the header portion from the TMCC signal and inversely scrambles the main data based on the extracted SYNC pattern.

Abstract: A transmission apparatus of orthogonal frequency division multiplexing for multiplexing a plurality of carriers orthogonal to one another to transmit a modulated signal. The transmission apparatus comprises a first modulator for outputting a code modulated in accordance a modulation scheme which can be applied with a synchronous detection for demodulation, a second modulator for outputting a code modulated in accordance with a modulation scheme different from the modulation scheme associated with the first modulator, and a distributing circuit for distributing the codes modulated by the first and second modulators to a plurality of carriers. The distributing circuit distributes the code modulated by the second modulator to all or some of carriers existing within a predetermined number of columns from at least one of both end regions of a signal transmission frequency band, and the code modulated by the first modulator to the remaining carriers.

Abstract: A signal transmission apparatus for a digital modulation type, wherein each of information codes is assigned to any one of a plurality of signal points arranged on an I-Q complex plane, a pilot signal used for demodulating said information codes and an auxiliary signal are assigned to be arranged on signals points on the I-Q complex plane, a signal modulated based on coordinates corresponding to the assigned signal points is transmitted, the transmitted signal is received, and the received signal is demodulated to reproduce the information codes, and wherein the signal points of said auxiliary signal and said pilot signal are arranged on different positions on said I-Q complex plane.

Abstract: An encoder and a decoder each having an error correcting operation, and a data transmission apparatus using them for data transmission in a multilevel modulation system. In transmission data is converted into parallel data. One bit thereof is inputted to a convolutional encoder to output two bits. Two bit data and another signal of the parallel data not inputted to the convolutional encoder are respectively separated into real part and imaginary part to independently decide signal points for the parallel data. In reception an area is similarly decided independently for real and imaginary parts and metric is assigned for the data. Real and imaginary parts are combined with each other for Viterbi decoding. Result thereof is fed to a convolutional encoder similar in constitution to that on transmission side. Using convolutional encoding output and decided area, transmission data is decoded.

Abstract: Data sequences correspond to L different parameter sets (effective symbol length, guard interval length, the number of carrier waves) and transformed into parallel data by respective serial/parallel converters, which are allocated to respective carrier waves for OFDM and subjected to inverse discrete Fourier transform by inverse discrete Fourier transformers to produce sampled values for the transmission waveform in the time domain. The sampled values are transformed into serial sequences of sampled values by parallel/serial converters and then into a single temporal sampling sequence by a temporal sampling sequence switching unit. A frame synchronizing symbol is added to the temporal sampling sequence and then transformed into an analog base band OFDM signal before it is converted up to a transmission signal. The frequency bandwidth of the OFDM signal is made smaller than a predetermined value defined by the bandwidth of the available transmission channel.