Operating instructions

ACCESSORIES

Standard

21552 15 ft. telephone cable with RJ-11 connectors

21553 9-pin male D-sub connector

21554 Shell for 9-pin D-sub connector

21551 12" mini-DIN LecNet expansion cable

21529 9-pin D-sub to stereo mini plug LecNet PC cable

40024 CH-40 wall transformer

LNETWIN LecNet software

M-TH3 TH3 instruction manual

35679 mini straight slot screwdriver

21580 5-pin depluggable terminal block

Optional

RCW-TEL wall plate remote control unit

RCW-DESK table top remote control unit

21592 24" mini-DIN LecNet expansion cable

GLOSSARY OF TH3 CONCEPTS

AGC

Automatic Gain Control. As used in the TH3, a circuit that compresses telephone receive volume levels, so that

weaker signals sound almost as loud as stronger ones. The trade-off is that background noise levels are also

increased in proportion to the AGC setting.

Bridging

Bridging refers to the interconnection of two otherwise separate interfaces. The TH3 not only has the ability to

communicate via telephone and to communicate via the 4-wire codec interface simultaneously, it has the ability to

bridge

the interfaces, such that codec signals are retransmitted over the telephone and vice versa.

Echo Suppression

A process whereby the gains of the transmit and receive paths are altered during a conversation, so that the path

that is least active receives the least gain. This has the effect of reducing both feedback and acoustic echo. The TH3

uses a patented echo suppression algorithm for smooth, transparent operation.

Hybrid

A device that converts a two-wire interface (e.g. the telephone network) to a four-wire interface, by isolating the

transmit and receive paths. The TH3 is a hybrid, with many special features.

Interface

As used in this manual, “interface” is used to distinguish groups of controls associated with the telephone and the 4-

wire codec. (e.g. “Press the CONNECT button for the telephone interface.”)

LecNet Anti-Echo

This is a special echo reduction feature available only when the TH3 is used with a Lectrosonics mixer. It allows the

TH3’s receive signal to participate in the automatic microphone mixing algorithm, so that the local microphones

receive less gain while the remote party is speaking.

Line Echo Canceller

The portion of a hybrid that removes as much as possible of the reflected transmitted signal from the receive path.

The job of the line echo canceller is made difficult by the highly variable conditions encountered on telephone lines.

The TH3 uses a specialized DSP chip for this purpose.