Tellabs 6943 Manual

Ttellabs
technical manual
76-836943
rev A
practice section 836943
©Tellabs, Inc., 1 May 1984
all rights reserved, printed in USA
6943 4Wire FXS SF Signaling Set
figure 1. 6943 4 Wire FXS SF
Signaling Set module
page 1
page 2
page 6
page 11
page 14
page 11
page 16
general description
application
installation
circuit description
block diagram
specifications
testing and troUbleshooting
contents
section 1
section 2
section 3
section 4
section 5
section 6
section 7
1. general description
1.01 The 6943 4Wire FXS (Foreign-Exchange,
Station-End) SF Signaling Set module (figure 1)
provides signaling and transmission interface be-
tween a 4wire facility that uses single-frequency
(SF) signaling and a 4wire metallic link that uses
the type of loop signaling normally associated with
the station end of a foreign-exchange (FX) or off-
premises-station (OPS) circuit. Specifically, in addi-
tion to providing full-duplex conversion between
the SF signaling on the 4wire facility and the FXS
signaling on the 2wire link, the 6943 contributes
passive level control (attenuation) in both the
transmit and receive channels and bump-type am-
plitude equalization in the transmit channel. Con- post-equalization is not required; balanced 600-
ventional 2600Hz SF tone is standard; other fre- ohm terminating impedance on the facility side;
quencies are optionally available by special order. baianced, switchable 1200, 600, or 150-ohm ter-
1.02 This practice section is reissued to cover minating impedance on the terminal (station) side;
the Issue 3 version of the 6943 module (Tellabs minimum-break transmit pulse correction; switch-
part number 836943). Please note that there is no selectable loop-start or ground-start operation;
Issue 2 version of the 6943. Functionally, the Issue switch-selectable build-out resistors (BOR's) for
3 module is virtually identical to its Issue 1 prede- currrent limiting on short 4wire links; strap options
cessor, differing mainly through the use of micro- that allow the signaling path (A and B leads) to be
processor control for increased circuit simplicity separated from the transmission path; an integrai
and reliability and through the ability to operate on SF tone oscillator (use of an external [master]
nominal -24Vdc as well as nominal -48Vdc input oscillator is optional); a circuit-status lead that can
power. Also, the conventional DIP-switch attenuator be used either as a local sleeve lead or as a traffic-
controls on the front panel of the Issue 1 6943 monitoring lead; alarm leads compatible with most
have been replaced by piano-style DIP switches on CGA formats; and internal access points available
the Issue 3 module, and the carrier-group-alarm at the module's card-edge connector for switched-
(CGA) option straps on the Issue 1 module have access testing or use with an associated echo-
been replaced by option switches on the Issue 3 control device.
version. In addition, the infrequently used option 1.05 The transmit portion of the 6943 converts
switch that allows separation of the signaling path station-end supervisory and dialing states to out-
from the transmission path on the Issue 1 6943 going SF tone signals. Tone is transmitted during
has been replaced by option straps on the Issue 3 station idle and also during the break portions of
module. dial pulses. A minimum-break transmit pulse cor-
1.03 Functionally equivalent to the Western rector ensures transmission of recognizable tone
Electric FRA Signaling Unit, the 6943 is designed pulses. A transmission-path-cut circuit with a
to operate in association with a 4wire or 2wire FXO nominal 15ms pre-cut delay interval prevents tran-
(foreign-exchange, office-end) SF signaling set sient interference with outgoing SF signaling.
(Tellabs 6944, 6924, or equivalent) at the opposite 1.06 The receive portion of the 6943 converts
end of the 4wire (SF) facility. incoming SF tone signals to station-end ringing
1.04 Features and options of the 6943 include and seizure states. Recognition delays prevent re-
the following: prescription optioning and alignment sponse to spurious SF tone bursts and to mom en-
capability in applications where transmit-channel tary tone interruptions. In the loop-start supervisory
page 1