1543Chapter 42
Assistive Listening Systems
by Glen Ballou
42.1 Nature of the Problem................................................................... 1545
42.2 Types of Assistive Listening Systems....................................................... 1545
42.2.1 Magnetic Induction Loops............................................................. 1546
42.2.1.1 Loop Design Criteria............................................................. 1546
42.2.2 Loop Location and Size............................................................... 1547
42.2.2.1 Loop Current................................................................... 1548
42.2.2.2 Loop Impedance................................................................ 1548
42.2.2.3 Electronic System............................................................... 1549
42.2.2.4 Installation..................................................................... 1550
42.2.3 FM Broadcast...................................................................... 1550
42.2.4 AM Broadcast...................................................................... 1551
42.2.5 Infrared........................................................................... 1552
42.2.5.1 Components of an Infrared System.................................................. 1553
42.2.5.2 Categories..................................................................... 1553
42.2.5.3 Coverage...................................................................... 1553
42.2.5.4 Ambient Light.................................................................. 1553
42.2.5.5 The infrared Link................................................................ 1553
42.3 Receivers............................................................................. 1555
References................................................................................ 1557