| 摘要 |
PURPOSE: An ATRU(ATM Transmit/Receive Unit) in an FLC-C(Fiber Loop Carrier-Curb) system is provided to offer an ATRU executing interface operations between an ATM exchange installed in a telephone office and an HDT(Host Digital Terminal) in an FLC-C system. CONSTITUTION: An ATRU consists of 4 optical access units(310), 4 signal processing units(320), 4 ATM-OAM processing units(330), 4 cell router units(340), 4 PECL/TTL conversion units(350), 4 OAM F/F units(360), a microprocessor unit(370), and a clock supply unit(380). The 4 optical access units(310) change STM-1 optical signals into electrical signals or STM-1 electrical signals into optical signals. Each of the signal processing units(320) is composed of various overhead processing parts and an ATM cell processing part. Each of the ATM-OAM processing units(330) is composed of an SRAM controller, an OAM cell recognition and function separation part, an OAM cell extraction part, an FM(Fault Management) function part, a loopback function part, a CC(Continuity Check) function part, a cell insertion function part, and a CPU access function part. The 4 cell router units(340) convert the VPI of an ATM cell transmitted from an ATM exchange, insert a routing tag for a destination device, and execute a routing operation to a cell bus(213). The 4 PECL/TTL conversion units(350) execute conversion between a PECL signal level and a TTL signal level. The 4 OAM F/F units(360) store extracted ATM cells. The microprocessor unit(370) is comprised of a CPU(371), a boot ROM(372), a local RAM(373), an address decoder(374), an IPC channel(375), and a serial channel(376). The clock supply unit(380) executes operations about clock supply.
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