HT98R068-1 Two-way Radio OTP MCU
Audio – Compandor Function Setting
Companding is applied 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. Set the companding amplitude turning
point by CLI CMD-012A in the TX mode and CLI CMD-012B in the RX mode. It’s
important to note that the TX/RX setting value is different in the same turning point. For
example, in the turning point of 100mV, the 1V signal in the TX mode will be measured to
be 550mV by MOD but in the Rx mode it is 1900mV. Note that if the signal exceeds the
limiter by companding. Control for this is setup using the I/O CMD-2Ch [6] bit as follows:
Compandor Function Enable Flow
Flow description:
<82C40>: Setup data: 40h. 2Ch [6] = 1 enables the compandor.
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