CSR8635 데이터 시트보기 (PDF) - CSR plc

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CSR8635

The CSR8635 QFN single-chip Bluetooth® audio ROM device targets mid-range stereo speakers and headsets.

CSR plc 

The PLC tries to re-synthesise the lost packet from the history buffer with the same pitch period. The PLC uses a highly

efficient 3-phase pitch estimator and performs cross-fading at the concatenation boundaries, i.e. the PLC attempts to

clean up the audio signal by removing the pops and clicks and smoothing out gaps. This improves the audio quality for

the user and the improved signal enables proceding processing blocks to perform better.

The PLC significantly improves dealing with bit errors, using the BFI output from the firmware. The DSP calculates an

average BER and selectively applies the PLC to the incoming data. This optimises audio quality for a variety of bit errors

and packet loss conditions. The PLC is enabled in all modes.

Note:

The PLC is enabled in all modes, HFK (full processing), pass-through and loopback by default.

16.2.9 Adaptive Equalisation (AEQ)

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designs.

16.2.12 Noise Dependent Volume Control

The NDVC block improves the intelligibility of the receive path signal by increasing the analogue DAC gain value based

on the send noise estimate from the send path noise suppression block. As the send noise estimate increases, the

NDVC algorithm increases the analogue DAC gain value. The NDVC uses hysteresis to minimise the artefacts

generated by rapidly adjusting the DAC gain due to the fluctuation in the environmental noise.

16.2.13 Input Output Gains

Fixed gain controls are provided at the input to the CVC system. The mic gain is used set the ADC level so that proper

levels can be set according to hardware constraints, industry standards and the digital resolution of the DSP fixed point

processor. The speake gain represents the output DAC which drive the speaker. The DAC level varies under software

control for events such as the Bluetooth volume, NDVC, tone mixing and other volume based activities.

Production Information

© Cambridge Silicon Radio Limited 2013

Confidential Information - This Material is Subject to CSR's Non-disclosure Agreement

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