Audio Engineering

664 Chapter 22

Frequency

Magnitude (dB)

Transmitter pre-emphasis and

receiver de-emphasis

20

15

10

5

102 103 104

0

 5

 10

 15

 20

Figure 22.11 : Typical preemphasis and deemphasis curves.

Receiver

expansion

Transmitter

compression

Output level (dB)

Input level (dB)

Compansion

 10

0

 20

 30

 40

 50

 60

 70

 80

 80  70  60  50  40  30  20  10 0

Figure 22.12 : Dynamic range compression at the transmitter and complementary

expansion at the receiver.

Transmitter units may be hand-held with a built-in microphone element or a body pack
unit provided with a minireceptacle for a microphone connection. The microphones
employed with body pack units are usually miniature dynamic or electret capacitor
microphones attached to short cables fi tted with mating connectors to that of the transmitter.