Microchip Technology AC164343 데이터 시트
© 2005 Microchip Technology Inc.
DS30177T-page 17
Software
dsPIC30F Acoustic Echo Cancellation Library
The dsPIC30F Acoustic Echo Cancellation (AEC)
Library provides a function to eliminate echoes
generated in the acoustic path between a speaker and
a microphone. This function is useful for speech and
telephony applications in which a speaker and a
microphone are located in close proximity to each other
and therefore, susceptible to signals propagating from
the speaker to the microphone resulting in a
perceptible and distracting echo effect at the far end. It
is especially suitable for these applications:
Library provides a function to eliminate echoes
generated in the acoustic path between a speaker and
a microphone. This function is useful for speech and
telephony applications in which a speaker and a
microphone are located in close proximity to each other
and therefore, susceptible to signals propagating from
the speaker to the microphone resulting in a
perceptible and distracting echo effect at the far end. It
is especially suitable for these applications:
• Hands-free Cell Phone Kits
• Speakerphones
• Intercoms
• Teleconferencing Systems
For hands-free phones intended to be used in compact
environments, such as a car, this library is fully
compliant with the G.167 standard for acoustic echo
cancellation.
environments, such as a car, this library is fully
compliant with the G.167 standard for acoustic echo
cancellation.
Features
• Only 2 user functions
(“AcousticEchoCancellerInit” and
“AcousticEchoCanceller”), both of which can be
called from either a ‘C’ or Assembly application
program
“AcousticEchoCanceller”), both of which can be
called from either a ‘C’ or Assembly application
program
• Full compliance with the Microchip dsPIC30F C30
C Compiler, Assembler and Linker simple user
interface – just one library file and one header file
interface – just one library file and one header file
• Highly optimized Assembly code, utilizing DSC
instructions and advanced addressing modes
• Echo cancellation for 16, 32 or 64 ms echo delays or
‘tail lengths’ (configurable)
• Fully tested for compliance with G.167
specifications for in-car applications
• Audio Bandwidth: 0-4 kHz at 8 kHz sampling rate
• Convergence Rate: Up to 43 dB/sec., typically > 30
dB/sec.
• Echo Cancellation: Up to 50 dB, typically > 40 dB
• Can be used together with the Noise Suppression
(NS) Library, since the same processing block size
(10 ms) is used
(10 ms) is used
•
“dsPIC30F Acoustic Echo Cancellation Library
User’s Guide” is provided to help the user
understand and use the library
User’s Guide” is provided to help the user
understand and use the library
• Demo application source code is provided with the
library. Accessory kit available for purchase includes:
an audio cable, headset, oscillators, microphone,
speaker, DB9 M/F RS-232 cable and DB9M-DB9M
Null Modem Adapter and can be used for library
evaluation
an audio cable, headset, oscillators, microphone,
speaker, DB9 M/F RS-232 cable and DB9M-DB9M
Null Modem Adapter and can be used for library
evaluation
• Contact Microchip sales for FREE evaluation
samples
∑
+
-
Acoustic Echo
Cancellation
FAR END
NEAR END
Far End
Speech
Speech
Far End
Speech
Speech
Near End
Speech
Speech
Near End
Speech
Speech
Receive Path
Adaptive
Filter
Send Path
User Application
Echo
Ordering Information:
SW300060-EVAL dsPIC30F Acoustic Echo Cancellation Library Software License (Evaluation Copy)
SW300060-5K
dsPIC30F Acoustic Echo Cancellation Library Software License (Up to 5K units)
SW300060-25K dsPIC30F Acoustic Echo Cancellation Library Software License (5K to 25K units)
SW300060-100K dsPIC30F Acoustic Echo Cancellation Library Software License (25K to 100K units)
AC300030
Accessory Kit (includes: audio cable, headset, oscillators, microphone, speaker,
M/F RS-232 cable, DB9M-DB9M Null Modem Adapter)
M/F RS-232 cable, DB9M-DB9M Null Modem Adapter)
DS70123
“dsPIC30F Acoustic Echo Cancellation Library Product Overview”
(Available at: www.microchip.com)
(Available at: www.microchip.com)