XRT73LC04A_08 Datasheet, PDF (40/64 Pages) Exar Corporation – 4 CHANNEL DS3/E3/STS-1 LINE INTERFACE UNIT

XRT73LC04A
4 CHANNEL DS3/E3/STS-1 LINE INTERFACE UNIT
REV. 1.0.2
3.2 THE RECEIVE EQUALIZER BLOCK
The purpose of this block is to equalize the incoming
distorted signal due to cable loss. The Receive
Equalizer attempts to restore the shape of the line
signal so that the transmitted data and clock can be
recovered reliably.
.
FIGURE 23. THE TYPICAL APPLICATION FOR THE SYSTEM INSTALLER
Transmitting
Terminal
0 to 450 feet of
Cable
Digital Cross-Connect
System
DSX-3
or
STSX-1
Pulses that are
compliant to the
Isolated DSX-3 or
STSX-1 Pulse Template
Requirement
0 to 450 feet of Cable
Receiving
Terminal
3.2.1 Guidelines for Setting the Receive Equal-
izer
This data sheet presents guidelines for setting the
Receive Equalizer, for the following conditions.
1. If the overall cable length, from the local Receiv-
ing Terminal to the Remote Transmitting Terminal
is NOT known.
2. If the overall cable length, from the Local Receiv-
ing Terminal to the remote Transmitting Terminal
is known.
3.2.1.1 If the Overall Cable Length is NOT
Known
This section presents recommendations on what
state to set the Receive Equalizer when the overall
cable-length, from the local Receiving Terminal to the
remote Transmitting Terminal is NOT known. For
DS3, STS-1 and E3 applications, enable the Receive
Equalizer by setting either the REQEN_(n) input pin
“high” or the REQEN_(n) bit-field to “1”. The remain-
der of this section provides an explanation why we
recommend enabling the Receive Equalizer for these
applications.
3.2.1.1.1 The Use of the Receive Equalizer in a
Typical DS3 or STS-1 Application
Most System Manufacturers of equipment supporting
DS3 and STS-1 lines, interface their equipment to ei-
ther a DSX-3 or STSX-1 Cross-Connect. While in-
stalling their equipment the Transmit Line Build-Out
circuit is set to the proper setting that makes the
transmit output pulse compliant with the Isolated
DSX-3 or STSX-1 Pulse Template requirements. For
the XRT73LC04A, this is achieved by setting the
TXLEV_(n) input pin or bit-field to the appropriate lev-
el.
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