Hitachi, Ltd.

Yagi Antenna Co., Ltd.

Osamu Shiotsu

Yukio Nakata

Motoyoshi Morito

Kaoru Suda

Matsuaki Terada

In a data signal demodulating circuit for demodulating data from a modulated signal burst in which a carrier signal is modulated by a data signal, noise elimination means is provided at at least one of the input and output of an AND circuit, to eliminate noise in periods during which there is no carrier present, by adding an output from a demodulator to an output from a carrier sense circuit, in order to completely eliminate noise occurring at the start and end of a demodulated data signal, and eliminate noise occurring during the rise time and fall time of the carrier sense circuit.

Demodulating circuit for data signal

In this data communication system, data communication is conducted through transmission lines between a plurality of stations. At each station, the presence of data to be sent is detected, the length of the detected data is measured, and that that station is disconnected from the transmission lines when the length of data exceeds a predetermined value, to inhibit the sending of data from that station.

Method and device for data communication

In a data communication system which has a common transmission line, a plurality of transceivers connected to the transmission line and data processors connected to the respective transceivers, and in which data from the data processor is delivered to the common transmission line through the corresponding transceiver, and data from the common transmission line is delivered to the data processor through the transceiver, so as to perform data communications among the data processors; a data communication system wherein said each transceiver comprises a first circuit which checks if an address of the data received from the transmission line has been received without any transmission error, a second circuit which checks if the address is one directed to the particular transceiver when the absence of the transmission error has been decided by the first circuit, a third circuit which turns back and delivers the received data when the address directed to the particular transceiver has been decided by the second circuit, and a fourth circuit which compares the sent data with the data turned back from another transceiver, the sending of the data being stopped when disagreement has been detected by the fourth circuit.

Data communication system with error detection/correction

A system for frequency modulation which generates first and second signals having different frequencies in a switching manner in accordance with the logical value of an input signal. The system includes an oscillator for generating a signal having a predetermined frequency; first and second frequency-dividers for subjecting the signal generated by the oscillator to frequency division by different integers l and m to generate first and second signals which are synchronized with each other; a third frequency-divider for subjecting an output signal from said second frequency-divider to frequency division by an integer n selected so that the product m.times.n is the least common multiple of l and m; a control device for controlling input data with an output signal from said third frequency-divider; and a switching device for selecting one of the output signals from the first and second frequency-dividers in accordance with the logical value of an output signal from the control device to generate an output which is passed through a filter for providing a modulated output.

System for frequency modulation

A data communication system including reflectors having first light emitting elements for radiating light and first light receiving elements for receiving light, a plurality of transceivers disposed confronting said reflectors and having second light emitting elements for radiating light and second light receiving elements for receiving light, and a data processing unit to be connected to the transceivers, wherein light corresponding to the data to be transmitted from the data processing unit is converged and radiated from the second light emitting element of the transceiver to the reflector, the light from the transceiver is received by the first light receiving element of the reflector, light corresponding to the data thus received is radiated from the light emitting element of the reflector to all of the transceivers confronting said reflector and is received by the second light receiving elements of the transceivers, and the data thus received is sent to the data processing unit.

Growing community of inventors

Asaka, Japan

Osamu Shiotsu