Clear-Com ECLIPSE TEL-14, Instruction Manual

Page: 19 / 37

2- 5
TEL-14 TWO-CHANNEL TELEPHONE INTERFACE
RELAY CONTACTS
A pair of relay contacts for each line ("A/A1 leads") rated at 2A @ 24
VAC are available on the DB-9M connector or the RJ-11 adapter.
This pair of contacts is normally open when the line is "on-hook"
and closes when the TEL-14 goes "off-
hook.” These contacts are
not connected to any other circuitry inside the TEL-14 and can be
used to energize a line-in-use indicator light on a standard multi-line
phone set, or for any other low-power application.
SETUP
AUTOMATIC TELEPHONE LINE NULL
The TEL-14 features sophisticated automatic nulling circuitry, in addition
to its integral echo cancellation system. This nulling capability is in two
parts:
•
The initial telephone line hybrid null is performed the first time a
telephone line is connected to the TEL-14 or whenever a
different telephone line is connected. This process is automatic,
but must be initiated by the user. The way to do this is described
later in this section and in Chapter 1,
“Operation.”
•
The continuous dynamic voice null takes place during each
telephone call. It automatically "fine tunes" the null and cancels
echoes.
The TEL-14 must null itself to the telephone line before normal
operation is optimal. This procedure is to be performed once
whenever the TEL-14 isconnected to a different telephone line.
Once this nulling procedure is performed, the TEL-14 will
remember the telephone line characteristics when it is removed
from the frame or loses power. It is necessary to null (minimize) the
sidetone (the sound of the operator's own voice in his or her
headset) when an external telephone line is placed in an intercom
environment. Ideally, there should be no portion of the talk signal in
the listen signal.
TEL-14'S SIDETONE NULLING PROCEDURE
Before calling the TEL-14 to automatically null it, connect the external
telephone line and any other devices that affect the line's impedance.
These include other telephone extensions connected in parallel on
the same line. The phone line must be active (turned on at the
central telephone office) during the nulling process, and all local
parallel phone sets must be plugged in but on-hook so the line is in
its normal operating state.
1.
Enable the "auto answer" function using the front panel button.
2.
Call the TEL-14 interface from a standard telephone set or cellular
phone. Do not call the TEL-14 from another TEL-14 in an
intercom.
3.
Press and hold the "auto answer" button for 5 seconds. The
green "auto answer on" LED will turn off and then turn on again
after 5 seconds.
When this happens, release the "auto
answer" button.
4.
Maintain silence on the telephone line. The TEL-14 will listen for
one second of silence before beginning. The "ring/of- hook" LED
will then flicker yellow and a series of tones will appear on the