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VCP description

Voice Communication Package (VCP) is a universal software package of digital signal processing technologies for voice applications enabling high quality, full duplex, noise free communication from various environments.  Users of mobile phones, hands-free car kits, Bluetooth headsets, industrial intercoms and other types of  voice terminals will all benefit from VCP quality. VCP enabled devices can be used in different scenarios and modes:

• Vehicle-mounted applications in which a hands-free terminal is mounted inside a car (e.g. hands-free car kit); cars of different types are supported with either car built-in or dedicated speaker(s) used.
• Hand-held applications in which a hands-free terminal is held at the arm's length and the internal loudspeaker is used (e.g. mobile speakerphone);
• Desktop applications in which a hands-free terminal is laying on a desktop surface and the internal loudspeaker is used (e.g. office speakerphone);
• Stationary applications where a hands-free terminal is mounted in a stationary device with its own loudspeaker(s) (e.g. portable speakerphone);
• Hand-held applications in which a terminal is held in hand near speaker's ear and mouth (e.g. mobile phone or handset);
• Headset applications, in which a terminal is placed on speaker's ear (e.g. Bluetooth headsets)

VCP includes a number of signal processing components. Basic VCP version includes components required by virtually all voice communication devices. Add-on components provide the user with additional benefits and can be enabled or disabled depending on the required functionality and available DSP resources.

Basic version of VCP includes the following signal processing blocks on the Tx (microphone) channel:

• Subband Acoustic Echo Canceller (AEC) with Residual Echo Suppressor (ES) and Comfort Noise Generator (CN)
• Noise Suppressor for stationary and transient noises reduction (NS)
• Multiband frequency equalizer (EQ)
• Dynamic Range Compressor (DRC)
• Noise Gate (NG)
• Automatic Gain Control (AGC)

Basic VCP also provides the “must have“functionality on Rx (loudspeaker) channel including:

• Automatic Gain Control (AGC)
• Dynamic Range Compression (DRC)

All signal processing blocks  are optional and can be enabled or disabled depending on the required functionality and available DSP resources.

Add-on VCP components provide advanced functionality that is not generally available in today’s voice communication terminals. Currently the following add-on components are available:

• Noise Suppressor (NS) for Rx (receiving direction) channel
• Automatic Volume and Equalization Control (AVQ) for Rx channel (replaces NDVC)
• Adaptive Dual Microphone (ADM) technology for Tx (microphone) channel

Technical information

VCP performance

• Fast convergence (< 300ms) with no initial echo
• Convergence in double talk and high noise
• Robustness to speaker signal distortions
• Echo canceller filter length is limited only by available memory (can be 250 ms and higher)
• Special room reverberation handling mechanism
• Residual echo level < -60dB
• Noise suppression with high frequency resolution up to -30 dB
• Maximal AGC gain 24dB
• Processing delay 32 ms
• Supported sampling rates: 8 KHz, 16 KHz, 32 KHz
• Fully compliant with VDA specification
• ANSI C reference code + platform-specific optimization

Availability

VCP is available on the following platforms:

• Blackfin DSP family (Analog Devices)
• ARM 7, 9, 11
• Renesas SuperH family
• CSR BlueCore5 Multimedia (with Kalimba DSP)

Porting on other platforms can be performed quickly

Interactive audio examples for VCP

Use control buttons on the interactive screenshots to play/stop/navigate.

Microphone signal containing speech of near-end speaker (male), loudspeaker echo (female speech) and a background noise of car passing by:

Processed microphone signal with cancelled echo and attenuated noise:

Additional information

VCP technical spesification >>
VCP leaflet >>
VCP for CSR BlueCore Multimedia leaflet >>

Please contact us for more information, current MIPS/memory consumption, audio examples and real time demo availabilities.

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