TNETEL1400

EtherLoop

™ TRANSCEIVER

SPHS004A – FEBRUARY 1999 – REVISED MARCH 1999

2

POST OFFICE BOX 655303

description (continued)

POTS

Line

POTS

Line

SE Modem

Ethernet

Network

Central Office

CE Modem

CE Modem

Remote Location

Ethernet

Network

Ethernet

Network

¤

¤

See Note A

NOTE A: Flexible multiplexing scheme allows one SE modem to interface with many CE modems.

POTS Phone

POTS Phone

Remote Location

Figure 1. Typical EtherLoop System

Figure 2 shows a block diagram of a typical CE EtherLoop modem. Ethernet data destined for the POTS wire

is received via 10Base-T interface and presented to the EtherLoop processor. The EtherLoop processor

performs Ethernet frame processing and buffer management. The EtherLoop processor sends buffered

Ethernet frames to the TNETEL1200 EtherLoop modem. The TNETEL1200 performs data modulation before

passing the modulated digital data to a digital-to-analog (DAC) converter. The resulting analog signal passes

to the TNETEL1400 transceiver, which acts as the line interface. The modem uses a half-duplex communication

protocol over the POTS wire, and data received from the POTS wire follows the reverse path back to the

Ethernet framer.

Ethernet

Network

Ethernet

Interface

POTS

Line

EtherLoop

Processor

TNETEL1200

EtherLoop

Modem

DAC

ADC

POTS

Phone

TNETEL1400

EtherLoop

Transceiver

SRAM

Voice

Band

Filter

¤

Figure 2. Typical CE EtherLoop Modem

Figure 3 shows a block diagram of a typical SE EtherLoop modem. Data flow follows the same path as in the

CE EtherLoop modem. In the SE application, the EtherLoop processor also performs round-robin arbitration

between each of the attached TNETEL1400 devices.