Sony Corporation

Nippon Hoso' Kyokai

Yasunari Ikeda

Takahiro Okada

Tamotsu Ikeda

Osamu Ito

Toshihisa Hyakudai

Yoshikazu Miyato

Yasunari Kozaki

Takashi Okada

Yutaka Tanaka

Hiroshi Nakano

Makoto Sasaki

Taiwa Okanobu

Hideyuki Matsumoto

Norihisa Shirota

Hirofumi Yuchi

Kazuhisa Funamoto

Toru Kuroda

Koichi Tagawa

Moriyuki Kawaguchi

Kenichi Tsuchida

Atsushi Yajima

Tadahiko Suzuki

Yasushi Fujimura

Isao Matsumiya

Takako Hidejima, Legal Representative

Yasuhiro Hidejima, Deceased

Naohiko Iai

A radio relay system () comprises a wireless camera () and a signal receiving relay station (). The wireless camera () wirelessly transmits signals to the signal receiving relay station () by using the OFDM modulation method. The wireless camera () and the signal receiving relay station () perform energy dispersion at the time of transmission-line-coding/decoding a transport stream. The PRBS seed (initial value) to be used for the energy dispersion can be externally modified and the user can arbitrarily select a value for the seed.

OFDM modulation/demodulation system

An OFDM receiver () is provided which includes a clock-frequency error calculation circuit () to calculate a difference in clock frequency between a clock for a received signal and an operation clock used in the receiver (), and a guard correlation/peak detection circuit () to determine an autocorrelation of a guard interval and detect a peak timing of the correlation signal. The guard correlation/peak detection circuit () incorporates a free-running counter, and outputs a count of the free-running counter at the peak timing to the clock-frequency error calculation circuit (). The clock-frequency error calculation circuit () uses a plurality of time-change rate detection circuits provided at different time intervals to calculate a time-change rate of an input count. The clock-frequency error calculation circuit () plots the time-change rates to generate a histogram and calculates a clock-frequency error from the histogram.

Ofdm demodulation device

The time required for switch the channel can be remarkably curtailed. When broadcasting signals through a plurality of information channels with an OFDM system, the plurality of information channels are multiplexed in the sense of frequency and collectively subjected to IFFT modulation for connected transmission instead of subjecting the plurality of information channels independently to OFDM modulation for transmission. With this arrangement, the efficiency of exploitation of frequencies is improved. According to the invention, the OFDM frames are synchronized for each information channel for the purpose of connected transmission. Then, the OFDM receiver can switch the information channel for signal reception, maintaining the frame synchronizing signals.

OFDM receiving device and OFDM receiving method

A digital broadcast receiving apparatus for receiving a broadcast signal generated by combining sub signals modulated using a random sequence generated based on an initial value set in accordance with a frequency of a broadcast channel by a signal transmission control use signal and a main signal generated based on information source data and reproducing the information source data contained in the received broadcast signal.

Digital broadcast receiving apparatus

OFDM modem system

A wireless transmission/reception system is provided which can use a limited frequency band most effectively and operates flexibly. A receiver (wireless receiver) has a transmission processing unit for transmitting a control signal, which defines a wireless frequency band and a transmission frequency for each of wireless transmission signals, to a plurality of cameras (wireless transmitter) #Cto #C, and the cameras have reception processing units for receiving the controls signal. Each of the cameras can change the frequency band and a center frequency of the wireless transmission signal according to the input control signal. As a result, output channels (Chto Ch) of the receiver can be changed to a broadband channel or a narrowband channel arbitrarily.

Wireless transmission/reception system

A transmission apparatus which prevents adversely affects from an adjacent channel even without provision of a guard band. An information sequenceinput to a mapping unit-of the transmission apparatus is mapped onto predetermined signal points by QAM modulation, etc. and output to a frequency converter-. The frequency converter-converts the frequency according to a center frequency of an input signal and outputs the result to a multiplexer. The other data series are processed in the same way as the data seriesare output to the multiplexer. The multiplexermultiplexes a plurality of input signals, while an IFFT processorperforms an inverse Fourier transform on the multiplexed signals all at once. The inverse Fourier transformed signal is quadrature-modulated by a quadrature modulator, converted to the RF band signal by the frequency converter, and transmitted from an antenna

Transmission apparatus and method and providing medium thereof

Influence from an adjacent signal is prevented even if a guard band is not provided. A phase comparison unitcompares a reference window signal input to a PLL circuitand a window signal supplied from a frequency division circuitand outputs the comparison result to an LPF. The LPFextracts a low frequency component from the input signal and outputs the same to a voltage controlled oscillator. The signal output from the voltage controlled oscillatoris supplied as a clock to units of an OFDM modulation circuitand, at the same time, supplied to the frequency division circuit. The frequency division circuitdivides the frequency of the supplied signal to thereby generate a new window signal and supplies the same to an IFFT unit. Further, the generated window signal is supplied to a PLL circuit. The PLL circuitgenerates a clock for controlling a frequency modulation circuitbased on the supplied window signal.

Transmitting apparatus and method and provision medium

An interference signal from an adjacent signal is prevented and a desired signal demodulated. A frequency conversion circuitconverts a received signal frequency to a first intermediate frequency signal of a first intermediate frequency higher than the frequency of the signal to be demodulated by 57 MHz. The first intermediate frequency signal is further converted to a second intermediate frequency signal of a second intermediate frequency by a frequency conversion circuit. The second intermediate frequency is a frequency lower than the 57 MHz of the first intermediate frequency by exactly a frequency &#xbd; of an FFT sampling f-clock. A clock generation circuitgenerates a signal of a frequency two times the FFT sampling clock, that is, four times the second intermediate frequency. The second intermediate frequency is sampled by the A/D conversion circuitbased on the signal supplied from the clock generation circuit, demodulated by a demodulation circuit, and subjected to an FFT operation by an FFT circuit, whereby the signal is demodulated.

Receiving apparatus and method and provision medium

A wireless relay system () comprises a wireless camera () and a reception relay station (). The reception relay station () comprises a plurality of external reception units () arranged at spatially different positions and an internal reception unit (). Each reception section () in the internal reception unit () demodulates a signal received in the external reception unit () and outputs a transport stream. At this time, each reception section () sets an error indicator flag to 1 for a TS packet causing a transmission error which exceeds the error correction capability. A TS synthesizer section () in the internal reception unit () completely synchronizes a plurality of input transport streams by referencing synchronization bytes, PID, and CC values, and selects to output a TS packet having the error indicator flag not set to 1.

Digital data radio receiving device and method

Transmitting device and method, and providing medium

A frequency interleaving circuit frequency-interleaves main signals generated according to sound data by parameters set according to frequencies of transmission channels. A sub-signal generating circuit generates sub-signals for transmission control including pilot signals. Mapping circuits modulate the sub-signals by using pseudo-random sequences generated based on initial values of random codes set according to frequencies of transmission channels. The frequency-interleaved main signals and the sub-signals modulated by the mapping circuits are OFDM-modulated. Then, they are converted to the frequencies of the transmission channels. An increase of a dynamic range of transmission signals can be suppressed by controlling the initial values of random codes set.

Digital broadcasting apparatus

A reception apparatus for OFDM signals having a short initial rise time since start of reception until outputting the sound and/or a picture. An OFDM reception apparatusof the ISDB-T standard presets the TMCC information at the outset in a memoryin association with each broadcasting station. This TMCC information contains the information on the RF frequency and the guard interval length, time interleaving pattern information, the information on the carrier modulation scheme and the information on the code rate of the convolutional code. When a user selects a broadcasting station, a control circuitreads out the TMCC information associated with the broadcasting station from the memory. The control circuitaffords the read-out TMCC information to each circuit to set e.g., the guard interval or the carrier modulation scheme.

Growing community of inventors

Kanagawa, Japan

Yasunari Ikeda