Abstract: A master apparatus includes a guard interval length determination portion that requests a plurality of slave apparatuses to cause the slave apparatuses to transmit respective OFDM signals of regular sequence in order without being mutually overlapped. The OFDM signal is obtained by adding a guard interval having a specified initial length to a regular valid symbol that is obtained by applying OFDM modulation to a regular data. A correlator outputs a cross correlation value between the regular sequence and a reception sample sequence. The guard interval length determination portion stores as a delay time a time interval from when the cross correlation value exceeds a first threshold value to when the cross correlation value exceeds a second threshold value. A common length of the guard interval is determined based on the maximum delay time among the delay times with respect to the respective slave apparatuses.

Abstract: In a communication system, nodes are coupled to a transmission path in a bus topology. The nodes communicate with each other via the transmission path using communication signals that have a communication frequency and are synchronized with a power supply signal. Each of the nodes includes a coupling portion that transmits and receives the communication signal and the power supply signal using electromagnetic induction in non-contact with the transmission path. Each of the nodes determines whether a collision of the communication signals occurs on the transmission path based on a voltage level of a signal that has the communication frequency and is induced at the coupling portion.

Abstract: In a master apparatus, a reference device generates a reference signal, a power feeding signal generation portion divides or multiples a frequency of the reference signal to generate a power feeding signal, a first communication carrier generation portion divides or multiples the frequency of the reference signal to generate a first communication carrier, a communication signal generation portion generates a communication signal, and a superimposition portion superimposes the communication signal on the power feeding signal.

Abstract: A master apparatus includes a guard interval length determination portion that requests a plurality of slave apparatuses to cause the slave apparatuses to transmit respective OFDM signals of regular sequence in order without being mutually overlapped. The OFDM signal is obtained by adding a guard interval having a specified initial length to a regular valid symbol that is obtained by applying OFDM modulation to a regular data. A correlator outputs a cross correlation value between the regular sequence and a reception sample sequence. The guard interval length determination portion stores as a delay time a time interval from when the cross correlation value exceeds a first threshold value to when the cross correlation value exceeds a second threshold value. A common length of the guard interval is determined based on the maximum delay time among the delay times with respect to the respective slave apparatuses.

Abstract: In a power line communication system, a master uses a twisted pair wire as a power line and a communication line and outputs a power signal and a data modulation signal to a slave. The slave includes an aperture antenna, a power monitoring portion, and a determining portion. The aperture antenna receives the power signal via the twisted pair wire by electromagnetic induction coupling of an electromagnetic field generated at the twisted pair wire in accordance with an applied current of the twisted pair wire. The aperture antenna has an aperture region facing an aperture region between twists of the twisted pair wire. The power monitoring portion monitors a power of the power signal received via the first aperture antenna. The determination portion determines whether to use another operation power received via the twisted pair wire on the basis of the power monitored by the power monitoring portion.

Abstract: A vehicular power line communication system includes a master and a slave. The master uses a pair of twisted wires, whose far ends are connected to each other to be loop-shaped, as a power line and a communication line. The master thereby outputs high-frequency signals via the pair of twisted wires, transmitting an electric power and data modulation signals. The slave includes an aperture antenna being loop-shaped to receive data modulation signals using an electromagnetic induction connection in an electromagnetic field generated in the pair of twisted wires in response to an energization current of the pair of twisted wires. The slave further includes an error rate monitor circuit which monitors an error rate of data which are obtained from demodulation of the data modulation signals received via the aperture antenna.

Abstract: A vehicular power line communication system includes a looped twisted pair wire, a master, and a slave. The master outputs a high-frequency signal to the twisted pair wire to transmit power and a signal. The slave includes a looped aperture antenna that receives high-frequency power of the twisted pair wire and a received power measurement portion that monitors received power received at the aperture antenna. The aperture antenna includes an aperture region facing an aperture region between twisted portions of the twisted pair wire.

Abstract: In a master apparatus, a reference device generates a reference signal, a power feeding signal generation portion divides or multiples a frequency of the reference signal to generate a power feeding signal, a first communication carrier generation portion divides or multiples the frequency of the reference signal to generate a first communication carrier, a communication signal generation portion generates a communication signal, and a superimposition portion superimposes the communication signal on the power feeding signal.

Abstract: A communication slave used in a communication network system includes a control device, a capacitive element, a voltage determining portion, and a time measuring portion. The control device controls communication with a master. The capacitive element is coupled between a high-potential side bus and a low-potential side bus. The voltage determining portion determines whether a voltage between the buses exceeds a threshold voltage. The time measuring portion measures a time from when a charge of the capacitive element through the buses is started to when the voltage determining portion determines that the voltage exceeds the threshold voltage. The control device sets an ID value for communicating with the master based on a length of the time measured by the time measuring portion.

Abstract: In a communication system, nodes are coupled to a transmission path in a bus topology. The nodes communicate with each other via the transmission path using communication signals that have a communication frequency and are synchronized with a power supply signal. Each of the nodes includes a coupling portion that transmits and receives the communication signal and the power supply signal using electromagnetic induction in non-contact with the transmission path. Each of the nodes determines whether a collision of the communication signals occurs on the transmission path based on a voltage level of a signal that has the communication frequency and is induced at the coupling portion.

Abstract: In a power line communication system, a master uses a twisted pair wire as a power line and a communication line and outputs a power signal and a data modulation signal to a slave. The slave includes an aperture antenna, a power monitoring portion, and a determining portion. The aperture antenna receives the power signal via the twisted pair wire by electromagnetic induction coupling of an electromagnetic field generated at the twisted pair wire in accordance with an applied current of the twisted pair wire. The aperture antenna has an aperture region facing an aperture region between twists of the twisted pair wire. The power monitoring portion monitors a power of the power signal received via the first aperture antenna. The determination portion determines whether to use another operation power received via the twisted pair wire on the basis of the power monitored by the power monitoring portion.

Abstract: A communication slave used in a communication network system includes a control device, a capacitive element, a voltage determining portion, and a time measuring portion. The control device controls communication with a master. The capacitive element is coupled between a high-potential side bus and a low-potential side bus. The voltage determining portion determines whether a voltage between the buses exceeds a threshold voltage. The time measuring portion measures a time from when a charge of the capacitive element through the buses is started to when the voltage determining portion determines that the voltage exceeds the threshold voltage. The control device sets an ID value for communicating with the master based on a length of the time measured by the time measuring portion.