摘要:
An optical receiver includes a squeezer for changing the quantum state of a signal lightwave to a squeezed state, a slave laser put in an injection locking state by the signal lightwave outputted from the squeezer, and an optical homodyne detector for carrying out optical homodyne detection for the signal lightwave outputted from the slave laser.
摘要:
An optical receiving method utilizing polarization diversity is disclosed in which first and second reference lightwaves having different frequencies and having polarization planes substantially perpendicular to each other, are combined with a signal lightwave to form a combined lightwave. The combined lightwave is subjected to heterodyne detection to obtain a detection signal and the detection signal is separated into first and second intermediate-frequency signals having different carrier frequencies. The first and second intermediate-frequency signals are converted into first and second baseband signals, respectively, and the first and second baseband signals are added to obtain an output signal.
摘要:
A digital signal multiplexing apparatus comprising variable multiplexers each of which can alter a multiplexed channel format every call in compliance with a subscriber's request, a fixed multiplexer which has a multiplexing capacity integral times as large as the total multiplexing capacity of the variable multiplexers and the multiplexed channel format of which is fixed, and fixed multiplexed signal demultiplexers each of which fixedly demultiplexes signals in a capacity integral times as large as that of each of the variable multiplexers into signals in a capacity equal to the total capacity of the variable multiplexers, wherein the outputs of the fixed multiplexed signal demultiplexers are distributed to the variable multiplexers through a distributing switch network, and the outputs of the variable multiplexers are multiplexed by the fixed multiplexer.
摘要:
A high-speed light emitting diode driver circuit for optical communication systems, in which an impedance circuit is provided between the collector and emitter of a drive transistor, and another impedance circuit is provided on the emitter side. The light emitting diode is connected to the collector side of the drive transistor. The light emitting diode is driven by an input pulse signal applied to the base of the drive transistor.
摘要:
A method of searching fault locations which is employed in a transmission system comprising a transmitting terminal having a transmitter for transmitting a digital signal; a receiving terminal having a receiver for receiving the digital signal; a plurality of repeaters which are placed between the transmitting and receiving terminals, and each of which receives and amplifies the digital signal from a preceding repeater section and deliver it to a subsequent repeater section; and a plurality of transmission lines for connecting the transmitter with the first repeater, the repeaters with each other and the final repeater with each other and the final repeater with the receiver, respectively. This method comprises the steps of coding an original signal to be transmitted in terms of two kinds of error detecting codes at the transmitting terminal to send out them from the transmitter; detecting an error of a received signal using one of the two kinds of error detecting codes at each repeater thereby to measure the error rate at one repeater section corresponding to each repeater; recoding a decoded received signal using the error detecting code employed to detect the error, and delivering it to a subsequent repeater section, and transmitting signals each of which represents the error rate at each repeater section measured at each repeater, to the transmitting terminal or receiving terminal.
摘要:
A bit synchronizing system for generating a timing signal corresponding to a transmitted pulse signal is disclosed in which the transmitted pulse signal is converted into a signal in which the number of pulses successively assuming the same polarity is limited to permit detection of frequency, the converted signal is integrated, a peak of integrated values is detected, the output of a voltage-controlled clock generator for generating the timing signal is processed in a similar manner to detect a peak with respect to the output, and the clock generator is controlled by a voltage corresponding to a difference between these two peaks, whereby the frequency of clock signal coincides with the bit rate of the transmitted pulse signal.
摘要:
Disclosed is an optical switching apparatus comprising means for converting serial optical or electrical signals into parallel signals in a time division mode, first and second time division switch groups and a space division switch group for cross connecting the signal of the optical or electrical signals, and means for generating the edited optical or electrical signals as serial signals again.
摘要:
An optical subscriber network transmission system comprises a first optical transmission line transmitting information from center to a subscriber and a second optical transmission line transmitting information from to the subscriber to the center. A plurality of auxiliary optical transmission lines are disposed between the center and the subscriber.
摘要:
A variable equalizer for compensating for the frequency characteristics of transmission media, comprising a plurality of variable circuits which are connected in cascade to an input terminal and which have the same variation characteristics, coefficient circuits which receive input and output signals of the variable circuits as inputs thereof and which multiply the inputs by coefficients, a plurality of impedance circuits which receive as inputs thereof signals with outputs of the coefficient circuits selectively combined and which have frequency-dependencies, and an adder circuit which adds outputs of the impedance circuits to provide an equalized signal as its output. No feedback circuit is required in the construction, and the plurality of variable circuits are constructed of the same circuits. Therefore, a variable equalizer which is capable of high-speed operation, whose circuit arrangement is simple and whose compensation accuracy is high is realized.
摘要:
To form a simple and economical variable equalizer, the equalizer is constructed of a differential amplifier having two input terminals to which an input signal to be equalized and an equalized output signal derived from the output terminal are applied, a first impedance circuit connected between the differential amplifier and the output terminal, and a series circuit having a second impedance circuit and a variable resistor connected in series between the output terminal and a ground terminal.