Nortel DMS-100 Series Maintenance Manual page 87

line card by an ordinary non-loaded (NL) pair of metallic conductors.
Simultaneous voice and extended signaling services are provided on the same
loop.
The transmission bandwidth on the loop is divided into two frequency bands:
1. Voice channel, 300-3400Hz
2. Signaling channel, 6-10kHz. Normal high-voltage signaling (ringing), is
substituted with low level signals.
The NT6X21AD is a single line circuit line card that is hardware backward
compatible with the NT6X21AC line card. The NT6X21AD is hardware
backward compatible with correct dual in-line package (DIP) switch settings.
The NT6X21AD provides the following enhanced features:
• reduced messaging noise
• DIP switch selectable balance impedance
• UDLC (universal digital loop carrier) optimized operation
• DIP switch selectable (0 or -3.5dB) gain in the D/A (digital to analog)
direction
• DIP switch selectable short-loop/long-loop (slp/llp), signaling levels
Feature AE1516 allows the entries to the NT6X21AD cardcode. Feature
AE1516 is necessary for the following actions:
• maintenance and diagnostics on the new, selectable signaling level
• voice receive D/A level
• balance impedance
DMS-100 Family OPM Maintenance Manual ISN07 (TDM)/SN07 (DMS) and up
Functional overview 2-11