Fujitsu Corporation

Tsuyoshi Ueshima

Mitsuo Kakuishi

Kazuo Tanaka

Eiji Shimose

Shigeki Takahashi

A high-speed signal input to and output from a high-speed optical interface part connected to an optical fiber transmission line is switched to different lines such that the switching is conducted by cross connect parts on an arbitrary basis. The high-speed signal is separated so as to obtain the low-speed signal. The low-speed signal output from the cross connect parts is separated so as to obtain the subscriber signal by signal terminal parts. Call connections are conducted for each subscriber by a time slot interchange part, whereupon a subscriber interface part performs analog-to-digital and digital-to-analog conversion so as to serve as an interface for a subscriber.

Digital loop carrier apparatus for large volume digital signal

The present invention provides, a two-system A/D converter, which provides a digital output signal with a higher conversion precision than is achieved by a single-system A/D converter. Conversely, by using a two-system D/A converter with a lower conversion precision, the present invention provides an analog output signal with a higher conversion precision than is achieved by a single-system D/A converter. Further, a digital signal clock changing unit produces data by performing high sampling of the first digital data trains, and the second digital data is synchronized with a second clock through an interpolation processing based on the timing difference between the first and second clocks. A high-precision A/D and D/A converter apparatus is thus realized by using two pulse code modulation coder/decoders (PCM.CODECs) and one digital signal processor (DSP) in a small, inexpensive structure.

Signal processing system for use in a digital signal clock changing

The present invention provides a two-system A/D converter, which provides a digital output signal with a higher conversion precision than is achieved by a single-system A/D converter. Conversely, by using a two-system D/A converter with a lower conversion precision, the present invention provides an analog output signal with a higher conversion precision than is achieved by a single-system D/A converter. Further, a digital signal clock changing unit produces data by performing high sampling of the first digital data trains, and the second digital data is synchronized with a second clock through an interpolation processing based on the timing difference between the first and second clocks. A high-precision A/D and D/A converter apparatus is thus realized by using two pulse code modulation coder/decoders (PCM.CODECs) and one digital signal processor (DSP).

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Yokohama, Japan

Tsuyoshi Ueshima