RAD Data comm LRS-24 Especificações descarregar pdf (Página 20)

Chapter 1 Introduction Installation and Operation Manual

1-6 Functional Description ASM-40CD Ver. 1.0

The setting of XMT clock depends on:

• Internal clock – from the modem’s internal crystal oscillator

• External clock – from the DTE

• Receive clock – recovered from received signal.

Internal FIFOs with PLL provide jitter attenuation and/or phase difference

correction either from the incoming analog signal (line side) or from the external

clock on the DTE side.

Encoder/Decoder

Provides the conversion from NRZ to HDB3, AMI or B87S on the transmission side

and back to NRZ on the receive side.

Line Driver

Provides a three-level alternate mark inversion signal according to ITU G.703

standard.

Receiver

Provides the receive signal for the clock and data recovery circuitry.

NRZ Interface

On the digital side, provides as interface choice of V. 24, V.35, V36, X.21, RS-530,

IR-ETH (Ethernet bridge) or IR-ETH/QN (Ethernet/Fast Ethernet bridge with VLAN

support).

Diagnostics

ASM-40CD provides remote digital loopback, local digital loopback and local

analog loopback diagnostics in compliance with the V.54 standard.

The local analog and remote digital loopbacks can be activated via the DTE

interface:

• V.35 – pins “h” and “j”

• V.24 and RS-530 – pins 18 and 21.

Test Pattern Generator and Receiver (ITU V.52)

This feature allows for quick and easy testing of the local modem as well as the

communication link. When the BERT command is activated, the circuit sends and

checks a standard 511-bit pseudo random pattern. If errors are encountered, the

ERR indicator lights up.

The test can be carried out in local loopback, in remote digital loopback or in

normal point-to-point operation opposite a remote ASM-40 modem (press the

PATT pushbutton on the remote unit or connect a bit error rate tester which uses

the standard 511-bit pattern).

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RAD Data comm LRS-24 Especificações Página 20