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Automatic Gain Control -- AGC
The audio input magnitude to microphones usually varies influencing the quality of the
audio output. This problem is usually resolved by the addition of an AGC circuit, however
this incurs a costs increase and requires circuit and component space. However this
device includes a fully internal AGC function which when accompanied with its internal
microphone amplifier (with a fixed gain of 5) and digital control, can fully implement an
automatic gain control mechanism. The range from 16mV~135mv (rms) which is selected
using the control bits I/O CMD-2Ch[0].
Audio Control - 2Ch Address
Bit
Name EN_Scram EN_Comp EN_Emp EN_NBW EN_WBW EN_HPF300 EN_VOX EN_AGC
AGC Enable Flow:
Flow description:
<82C01>：Setup data：01h. 2Ch[0] = 1 enables the AGC function.
AGC application circuit (Gain value = 5 ):
Parameter Setting
The Audio processor frequency generation, threshold detection, variation values, drop
time and limiting values can be modified according to actual requirements and generate
the required setting parameters using the application program in the appendix:
Use the program HT98R068_AppProg_Vxx.exe to generate the required parameters.
For details, see the HT98R068_AppProgNote_Vxx.pdf.
7
6
5
AGC Selection Register
28
HT98R068 Two-way Radio MCU
4
3
2
1
0
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