Abstract: A small-sized LSI variable equalizer is provided for accurately equalizing waveforms of signals transmitted via transmission lines of different distances. Variable equalizer units capable of stepwise changing the equalizing characteristics thereof are connected in series with each other with the variable equalizer units having variable step widths different from each other. An output signal of the variable equalizer units is compared with a reference signal to convert the comparison output signal to a digital signal which includes an upper order bits and lower order bits, whereby one of the equalizer units which has a wide variable step width is controlled by the upper order bits and the other of the equalizer units which has a narrow variable step width is controlled by the lower order bits.

Abstract: In a time division multiplexing system for multiplexing a plurality of channels having mutually-independent bit rates, the improvement wherein the pulse signals of each channel are converted into codes so that the information "1" is represented by a pulse having a width of two consecutive transmission clock periods ("0,0" or "1,1") the information "0" is represented by a pluse having a width of a single transmission clock period ("0" or "1"), and polarities of adjacent pulses are always different from each other; the pulse signals are compressed time-wise in a frame unit; and a frame synchronizing signal and a channel synchronizing signal, each consisting of marks or spaces having a duration of at least three consecutive transmission clock periods, are added to the intervals between the time-compressed frames to thereby perform time division multiplexing.

Abstract: In a digital signal transmission system wherein input digital signals having an arbitrary bit rate are converted into digital signals of a bit rate higher than that of the input digital signals and then transmitted through a signal format converter; in order to realize the signal format conversion in real time the signal format converter is constructed of a buffer circuit of small capacity, a circuit which writes the input signals into the buffer circuit at the bit rate of said input signals and which reads out the written signals at the bit rate of a transmission line, a circuit which distinguishes the signals to-be-read as a mark, space and empty, and an encoding circuit which converts the mark, space and empty into pulse signals discernible with the unit being a time slot of the transmission line or integral times the time slot, in dependence of the levels of pulses or the numbers of successive pulses (run length).

Abstract: 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.

Abstract: 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.

Abstract: A variable equalizer whose frequency characteristic varies in a range of 1-1/Y(f).sup.2when the gain x of a variable amplifier varies from 0 (zero) to .infin. (infinity), and which reduces the number of shaping networks for the variable frequency characteristic.It is constructed of a forward pass circuit which consists of a variable amplifier and a frequency-dependent first circuit connected in the order mentioned between input and output terminals, a feedback pass circuit which is dependent upon the frequency and which feeds-back an output of the variable amplifier to an input thereof, and a feed forward pass circuit which is independent of the frequency and which feeds forward part of the input of the variable amplifier to an output of the first circuit.

Abstract: A variable equalizer is provided which, using a single variable resistor, can make compensations in both the directions of the gain side, and the loss side and can set a reference gain as desired.An input signal to be equalized is received as an antiphase input signal of a differential amplifier, an output signal which has been equalized is fed back to the antiphase input signal, and a difference signal between an in-phase input signal and the antiphase input signal is delivered as an output. A resistor is connected between an input terminal and ground, first and second impedance circuits and a variable resistor are connected between an intermediate point of the first-mentioned resistor and ground in the order mentioned, and a voltage at the junction point between the first and second impedance circuits is used as the in-phase input signal.

Abstract: Apparatus for producing an optical fiber including apparatus for heating an optical fiber preform, apparatus for drawing out the optical fiber from the optical fiber preform whose fore end part has been made molten by the heating and for taking up the drawn out fiber, apparatus for causing a gas to flow along the outer peripheral surface of the molten part of the optical fiber preform, and apparatus for controlling both the flow rate of the gas and the drawing-out speed of the optical fiber according to a fluctuation in the diameter of the optical fiber.

Abstract: 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.

Abstract: A variable equalizer adapted to be fabricated in an integrated circuit structure and having improved compensation characteristics comprises a parallel connection of two circuits, one including a series connection of a first impedance circuit (impedance: Zy) and an input A.C. signal source circuit having a voltage v.sub.i, the other comprising a series connection of a second impedance circuit (impedance: Z.sub.x) and an A.C. signal source circuit having a voltage amplitude v.sub.z which is equal to v.sub.i (K/Z.sub.y).sup.2, where K is a constant, and the second impedance circuit, consists of a variable resistor.

Abstract: In order to realize a precision variable equalizer of little errors by a simple circuit arrangement, a plurality of variable transmission circuits having variable transfer coefficients are connected in series between input and output terminals, and feed-back and feed-forward are applied from input and output sides of the respective variable transmission circuits to input and output portions of the variable equalizer through transmission networks having specified transfer characteristics.

Abstract: An inductorless variable equalizer comprises input and output terminals. A first transmission network is situated in the forward path between the input and output terminals and has a variable transfer coefficient; second and third transmission networks are situated in the feedback and feedforward paths, respectively, between the input and output terminals. Each of these networks has a fixed transfer coefficient and the transfer coefficients of the feedback and feedforward networks having polarities opposite each other.