RT9107B

21

DS9107B-00 November 2016

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Dynamic Range Control (DRC)

DRC is a specific feature to automatically adjust the volume gain corresponds to different input signal. With DRC

function, the output dynamic range is under controlled from input amplitude is unknown or varies over a wide range.

RT9107B provide three thresholds as dynamic range compression (DRCx_T), extension (DRCx_E_T) and Noise Gate

(DRCx_N_T). For the application of compression and extension, the slope ratio can be programmed as DRCx_K and

DRCx_E_K, respectively.

DRC function is composed of several parts as following Figure.

Then, the filtered signal is compared with the given compression threshold. After the comparison between Input signal

amplitude and threshold, the Attack Rate (DRCx_AA) determines how quickly the DRC gain decreases when the signal

amplitude is high. The Decay Rate (DRCx_AD) determines how quickly the DRC gain increases when the signal amplitude

is low.

Compressor rate

Compressor/limit

Expander

Noise gate

Dynamic

range

Input Level (dB)

window

s

-1

t

f ln(1-ae)



Energy

Filter

Compression

Filter

Attack/Decay

Filter

Gain

AE

1-AE

AA

1-AA

AD

1-AD

Audio Input

Audio Output

Alpha Filter Structure

Z

-1

-

Note :

= 1









The input signal passes through the programmable Energy Filter (DRCx_AE). The Filter structure is shown in following

Figure.

The time constant of each filter can be determined by below equation :