Abstract: An optical fiber protective unit includes: a reticulated tube; and a tubular member that is inserted through the reticulated tube and that is configured to accommodate a plurality of optical fibers. The reticulated tube is disposed on an outer periphery of the tubular member in a state folded in a longitudinal direction. Both end parts of the reticulated tube are located on the outer periphery of the tubular member.

Abstract: First and second counters in a pulse width modulating circuit, whose respective outputs determine the trailing and leading edges of a pulse width modulated signal, count input clock pulses at a constant speed. The number of the pulses applied to the second counter during a cycle relative to the number of the pulses applied to the first counter is increased or decreased by one in response to a modulating pulse to change the counting phase of the second counter thereby changing the width of the pulse width modulated signal. Gates freeze the phases of the two counters at minimum and maximum pulse widths of the pulse width modulated signal to avoid abrupt jumps from minimum to maximum or vice versa.

Abstract: A synchronizing signal generator for a PAL television signal processing system includes a frequency divider which divides a reference signal from a reference oscillator to produce a color sub-carrier signal. A pulse subtracting circuit subtracts a predetermined number of pulses per line to remove an offset in the reference oscillator frequency relative to a frequency required for producing synchronizing signals. The resulting offset-removed signal is frequency divided to provide television horizontal and vertical synchronizing frequency signals. The synchronizing frequency signals are used to produce a color framing signal which can be used by external circuits to identify a particular one of each of the sequential sets of eight fields which make up a PAL television signal. The color framing signal also resets or presets the frequency divider for establishing a predetermined phase relationship between the color sub-carrier signal and the color framing signal.

Abstract: A method of and apparatus for converting a plural-bit digital signal to a pulse width modulated signal which, thereafter, can be filtered to derive an analog signal level corresponding to the value of the digital signal. A periodic timing signal is produced and each period thereof is divided into predetermined sections. The value of the digital signal is divided by a factor equal to the number of predetermined sections, and the divided digital signal is converted into a corresponding pulse width modulated signal during each of the timing sections. The pulse width of the pulse width modulated signal in selected ones of the timing sections is selectively increased by a predetermined amount in the event that the divided digital value is not an integral number. In particular, the number of such timimg sections wherein the pulse width of the pulse width modulated signal is increased is equal to the remainder obtained after the value of the digital signal is divided.