ABB ETL600, Instruction Manual

Page: 70 / 382

ABB Switzerland Ltd
1KHW001489-EN ETL600
3.4. Analog Services
The analog services comprise the following applications:
Telephony
•
Point-to-point hot line (direct phone),
•
Remote subscriber,
•
4-wire PAX connection with E&M signaling,
•
2/4-wire PAX connection with E&M signaling and hybrid control,
•
E&M signaling,
•
Service phone.
Teleoperation
•
Transmission of AF data signals from modems
•
Programmable transit filters
Connection of external teleprotection equipment
•
External teleprotection equipment instead of or in addition to the
integrated NSD600
•
Signal boosting control
The ports for all these applications are located on the O4LE board(s).
3.4.1. Telephony
One APLC channel of the ETL can carry one telephony channel, its
upper edge frequency being programmable to 2.0, 2.2, 2.4, 2.6, 2.8,
3.0, 3.2 or 3.4 kHz
2 . The speech signal is scaled to the nominal level
of 0 dBm0 (weight = 1.0) for transmission over the link. To prevent
saturation of the ETLs RF-signal in case the level of the incoming
speech signal is excessively high, the speech signal inside the ETL is
limited to a maximum level of +3 dBm0.
3.4.1.1. Point to point hot line (direct phone)
O4LE
a/b
ETL600
O4LE
ETL600
a/b
Direct
Phone
Direct
Phone
Fig. 3-26 Point to point hot line
In this application, a direct connection between two phones is
established. As soon as either of the phones is picked up, the phone
on the other side is ringing intermittently until it is picked up also. In-
2
For the case of 3 APLC channels in 8 kHz, the range of available speech
bandwidths is restricted.
3-38 November 2005 Structure and Function