MODMER / Long Entry

Realization of a 2048 kbit/s-os interface (MH89790)

In the measurement the G.703/704 2048 kbit/s-os interface is realized by a PCM trunk interface circuit of type MH89790 on the ISDN developing card.

A simplified block diagram of the circuit:

Transmission unit of the circuit generate a standard PCM signal flow from the signals arriving from F0 C2 DSTI CSTI1 wires of the user?s side.

Receiving unit of the circuit obtains the clock from the standard PCM signal flow arriving at the PCM IN input, then it forwards the received PCM frame towards the user through the DSTO wire.

F0, DSTI CSTI0 CSTI1 DSTO CSTO wires are ST-bus data wires, thus the signal with a serial format to be forwarded is already organized into PCM frames. Data, signal and status signals obtained from the PCM signal at the output of the PCM are also PCM-framed.

Main characteristics of the circuit:

Insertation of a synchronous pattern, and detection
Optional CRC check
Remote-end error report
HDB3 coding and decoding
Channel associated (CAS) or common chanell (CCS) signalling
Programmable digital attenuatior in the transmitter
flexible storage of two frames in the receiver
ST-BUS interface

Control words can be set in the menu of the interface, the status information can be read from the menu.