U4082B-DEV-BOARD Atmel, U4082B-DEV-BOARD Datasheet - Page 9

• Manufacturer Part Number: U4082B-DEV-BOARD
• Description: WiFi / 802.11 Modules & Development Tools Voice Switched Circuit
• Manufacturer: Atmel

3.10
4743D–CORD–03/06
Summary of the Truth Table
Two conditions that can cause fast idle mode:
Figure 3-4.
• The circuit will switch to transmit if
• The circuit will switch to receive if
• The circuit will switch to fast idle mode if the level detectors disagree on the relative strengths
• The circuit will switch to slow idle mode when
of the signal levels, and at least one of the background noise monitors indicates speech. For
example, referring to the block diagram
the microphone amp output (TLI2) to override the speaker signal (RLI2) and there is sufficient
signal at the receive input (RLI1) to override the signal at the hybrid output (TLI1), and either
or both background monitors indicate speech, then the circuit will be in fast idle mode.
- both transmit level detectors sense higher signal levels relative to the respective
- the transmit background noise monitor indicates the presence of speech.
- both receive level detectors sense higher signal levels relative to the respective
- the receive background noise monitor indicates the presence of speech.
- when both talkers are attempting to gain control of the system by talking at the same time,
- when one talker is in a very noisy environment, forcing the other talker to continually
- both talkers are quiet (no speech present), or
- when one talker's speech level is continuously overridden by noise at the other speaker's
receive level detectors (TLI1 versus RLI1, TLI2 versus RLI2), and
transmit level detectors, and
and
override that noise level. In general, fast idle mode will occur infrequently.
location. The time required to switch the circuit between transmit, receive, fast idle and
slow idle is determined in part by the components at pin 14 (see the section on switching
times for a more complete explanation of the switching time components). A diagram of
the C
T
circuitry is shown in
C
T
Attenuator Control Block Circuit
R
C
V
15
14
C
T
T
B
T
I
1
Figure
60 µA
2 k
I
2
3-4, and operates as follows:
(Figure 1-2 on page
Attenuator
control
+
-
4
AGC
Volume control
Dial tone detector
C1 to C4
To attenuators
2), if there is a sufficient signal at
U4082B
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