Abstract: A ring oscillator has its inverter states in respective inner stages change at a time unit longer than a period of a master clock MCK and is oscillated at a period longer than the period of the master clock MCK. The inverter states of the respective stages of the ring oscillator are captured by a flipflop circuit and a value indicating each of these states is subtracted by a subtractor from numerical figures indicating the inverter states in the respective stages of the ring oscillator as captured at the timing of the master clock MCK by other flipflop circuits. The difference is output as a signal indicating the position of the input signal edge.

Abstract: In a magnetic recording and reproducing apparatus, an audio signal and a video signal are assigned to first and a second channels of an ordinary magnetic recording and reproducing apparatus in respectively, and recorded at a transmission rate twice that of the usual rate, so that it is possible to record an audio signal without tone quality degradation to record a video signal together with the audio signal.

Abstract: An integrated circuit includes a drum phase detection signal generating unit formed by two-stage amplifiers and a comparator, a drum frequency detection signal generating unit similarly formed by two-stage amplifiers and a comparator, a capstan frequency detection signal generating unit, and a supply reel frequency detection signal generating unit and a take-up reel frequency detection signal generating unit each formed by a comparator. From each associated voltage source a predetermined voltage is applied to each of the first stage amplifiers, second stage amplifiers, and to the comparators of the drum phase detection signal generating unit, drum frequency detection signal generating unit, capstan frequency detection signal generating unit, supply reel frequency detection signal generating unit, and the take-up reel frequency detection signal generating unit.

Abstract: A phase locked loop circuit is arranged such that the frequency of an input reference clock signal is selected on the basis of a first or second transmission rate of an incoming digital signal, whereby an output digital signal correctly synchronized with the incoming digital signal having the first or second transmission rate can be transmitted. Also, the phase locked loop circuit is arranged so that a first or second central frequency value and a first or second boundary frequency value are set in response to the first or second transmission rate of the incoming digital signal so that, if a frequency value of an output digital signal lies outside of a range of the first or second boundary frequency values, the frequency of the output digital signal is set to the first or second central frequency values. Thus, the phase locked loop circuit of the invention can deliver the output digital signal correctly synchronized with the incoming digital signal having the first or second transmission rate.

Abstract: An ultrasonic flaw detection method in which defects in the weld zone of an electric resistance welded steel pipe are detected by projecting an ultrasonic wave (a) having a frequency range of from 25 MHz to 500 MHz at an angle of incidence of from 0.degree. to 12.degree. onto the weld zone of the pipe. In addition by projecting another ultrasonic wave (b) having a frequency of from 2 MHz to 10 MHz at an angle of incidence of from 15.degree. to 27.degree. onto the same weld zone enables discrimination between cold weld defects and other defects such as inclusions and penetrators.

Abstract: A converted digital signal is provided in an NRZI (non-return to zero, inverted) code with a zero DC component and with a maximum predetermined number of bits between level transitions in the signal. The base digital signal is divided into m-bit base words, each of which is then converted into an n bit converted code word to form a converted digital signal suitable for recording. The n-bit converted code word is selected from a plurality of primary combinations or code words having a DC component substantially equal to zero when NRZI-coded and a plurality of secondary combinations or code words having a DC component with an absolute value of two when NRZI-coded. A variance of the DSV (digital sum variation) of each primary combination when NRZI-coded and a polarity of the DC component of each secondary combination when NRZI-coded are altered in response to the DSV at the exit of the preceding converted digital signal.

Abstract: A method for converting a digital data into an NRZI-coded digital signal is disclosed which is carried out by the steps of first detecting if the value of every even numbered bit of the digital data is digital zero, second detecting if two bits of the detected even numbered bits having digital zero value and a preceding odd numbered bit have a DC component, producing a detecting signal according to the result of the second detecting; and converting the digital data into the NRZI-coded digital signal by using the detecting signal.

Abstract: A converted digital signal is provided in NRZI code with a DC component of zero and with a maximum of four bits between level transitions in the signal by dividing the base digital signal into eight-bit base words, each of which is then converted into a ten-bit word signal that has 1024 (2.sup.10) possible combinations, of which there are 193 that begin with no more than two digital zeros, end with no more than one digital zero, have no more than three consecutive digital zeros anywhere else, and have a DC component of zero when NRZI coded, and each of which is used to represent one eight-bit base word. Each of the remaining 63 of the total 256 (2.sup.8) base words is converted into a secondary ten-bit combination having a "convention" DC component of +2 or -2.

Abstract: A digital signal is divided into a series of base words with each m bits of data. Each base word is converted to a converted word having n bits of data, wherein each of n and m is an integer and n is greater than m and the converted word has a predetermined maximum number of consecutive digital zeroes. The value of every odd-numbered bits of said converted word is detected. The converted word is controlled in response to the result of the detection and modulated as an NRZI (non-return to zero, inverted)-coded digital signal with a DC component of zero.

Abstract: For recording an analog signal by means of two recording heads equally spaced on a rotating drum, a magnetic tape is wrapped guide drum with an angular range of 90.degree., so that there are recording periods when a head is tracing the tape and free periods when neither head is tracing the tape. The analog signal to be recorded is converted to pulse code modulated (PCM) signals having real time periods longer than the recording periods. The free periods, during which neither head is in contact with the recording medium, are used to add redundant data such as parity data and a cyclic redundancy check (CRC) code to the PCM signals. The composite signal, which represents a PCM signal having the parity data and CRC code added to it, is time-base compressed to a period substantially equal to the recording periods and is recorded on the recording medium by one of the heads during its recording period. To reproduce the signal, the same head arrangement is used.

Abstract: A process is disclosed for producing powdery polycarbonate from a polycarbonate solution which comprises:(a) charging the solution into the feed opening of a disolvating apparatus, the apparatus being composed of a casing and having at least two screws incorporated therein, the screws meshing with each other; the apparatus comprising two parts; a evaporating zone and a powdering zone; a space being provided above the screws in the evaporating zone, the space extending in the axial direction of the screws and having at least one degassing opening, and side and bottom portions of screws generally fitting with the casing in the evaporating zone; top, side and bottom portions of screws generally fitting with the casing in the powdering zone, heating means being installed in the casing and/or screws;(b) in the evaporating zone, evaporating the solvent of the polycarbonate solution using the heating means while moving the solution by the screws;(c) powdering the dried polycarbonate in the powdering zone; and(d) dis