HT98R068 Two-way Radio MCU
Audio Advanced Function
The device provides multiple audio processors, including Scrambler, Compandor,
Emphasis, HPF, LPF…etc. for a wide range of applications. The function switches are
located at I/O CMD-2Ch[7-2]. As the Audio Processor operating frequencies are different,
there are some restrictions in enabling the function groups and for using the Tx/Rx. See
the appendix for reference:
Audio Control - 2Ch Address
Bit
7
6
5
4
3
2
1
0
Name
EN_Scra
m
EN_Com
p
EN_Em
p
EN_NBW
EN_WB
W
EN_HPF3
00
EN_VOX
EN_AG
C
Advanced audio process control register
Audio -- Scrambler \ De-scrambler Function Setting
Scrambling implements reverse signal processing execute inverse handling to the signal,
which is an encryption method for the transmitted signals. In the Tx mode, signals
transmitted through a scrambler will become meaningless and impossible to use.
Likewise, when in the Rx mode, after the descrambler is applied, the scrambled signals
will be returned back to their original signals. This function is controlled by the I/O
CMD-2Ch[7] bit by using the following setup:
Scrambler Enable Flow:
Flow description:
<82C80>
：
Setup data: 80h. 2Ch[7] = 1 enables the Scrambler.
Audio -- Compandor (Compressor \ Expander) Function Setting
Companding is used to lower the dynamic range by compressing or expanding the
signals. Dynamic range: 60dB, output 30dB, value = 0.5 (subject: MIC in). In a radio
transmission process, the RF signals will include noise after reception. Therefore, before
the signals are transmitted, the data is compressed by a certain setup ratio. When the
original signals are retrieved by the descrambler expanded with the same ratio, most of
RF noise that does not belong to the original signals will be eliminated after the expansion
and will thus greatly reduce the noise in the output. Control for this is setup using the I/O
CMD-2Ch[6] bit as follows:
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