User manual

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CHAPTER 1
Introduction and Specification
Introduction
The IFB System is a one-way IFB (Interruptible Feedback)
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communications system (a program interrupt system) created
especially to meet the critical requirements of the television broadcast industry, as well as other live or recorded media
applications. The system is composed of User Stations, Central Electronics and Control Panels. A modular approach assures
the optimum configuration for each installation. Should system expansion be desired, additional components may be added as
necessary. A typical system may consist of the following: up to four (4) Control Panels, one (1) Central Electronics unit, four
(4) User Stations, and assorted cabling and interconnect units. The maximum standard configuration allows four (4) Control
Panels, three (3) Central Electronics, and 12 User Stations.
User Station Model 4020
The User Station, a small belt pack package, allows the talent to receive the audio signals designated by the Central Electronics
and the Control Stations and may be worn by talent, such as newscasters, musicians, sportscasters, etc. Behind-the-scenes
personnel may also find the IFB feeds useful for production coordination and control. These may be production assistants,
audio boom operators, stage monitor mixers, on stage producers, etc. Each belt pack contains the necessary electronics to
provide a stereo audio signal to the user. Two (2) power amplifiers rated at 1/2Watt each are capable of driving any set of
headphones or loudspeakers. Thus, the IFB can be conveniently extended to dressing rooms or other off-camera areas where
communication is desirable.
The line input to the belt pack is driven from the Central Electronics unit. This signal contains the audio information as well as
the DC voltage necessary to power the belt pack. Both the left and right signals are carried on a standard 2-conductor
microphone cable. The left channel is designated as interruptible, the right channel non-interruptible. Separate jacks are
provided for mono and stereo headphones. Individual left and right volume controls on the belt pack enable the user to adjust
listening levels for personal comfort. When mono headphones are used, they are fed only the left channel program –
interrupted program audio.
A standard TW Intercom belt pack is fully compatible with this system and may be used in place of the Model 4020 User
Station, if necessary.
1. IFB is also known as IRF, Interrupted Return Feed and foldback.