Abstract: An optical multiplexer/demultiplexer module including a first ferrule assembly having a first sleeve and a first ferrule inserted and fixed in the first sleeve, the first ferrule having first and second optical fibers; a first element fixed to the first ferrule assembly, the first element having a first lens and a bandpass filter; and a second element fixed to the first element, the second element having a wedge plate for optical path correction, the wedge plate being formed of glass. The optical multiplexer/demultiplexer module further includes a third element fixed to the second element, the third element having a second lens; and a second ferrule assembly fixed to the third element, the second ferrule assembly having a second sleeve and a second ferrule inserted and fixed in the second sleeve, the second ferrule having a third optical fiber.

Abstract: An optical multiplexer/demultiplexer module including a first ferrule assembly having a first sleeve and a first ferrule inserted and fixed in the first sleeve, the first ferrule having first and second optical fibers; a first element fixed to the first ferrule assembly, the first element having a first lens and a bandpass filter; and a second element fixed to the first element, the second element having a wedge plate for optical path correction, the wedge plate being formed of glass. The optical multiplexer/demultiplexer module further includes a third element fixed to the second element, the third element having a second lens; and a, second ferrule assembly fixed to the third element, the second ferrule assembly having a second sleeve and a second ferrule inserted and fixed in the second sleeve, the second ferrule having a third optical fiber.

Abstract: A modem signal detecting system for an adaptive differential code modulation system, which is intended for detecting a modem training signal, comprises a comparison and decision circuit which receives an input signal from a signal power calculator and compares a signal power level during a silent period and a training period of a modem training signal. The comparison and decision circuit then decides whether or not the transmission quality of the transmission line is suitable for the modem communication.