Specifications

© 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:
• 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.
Features
• Only 2 user functions
(“AcousticEchoCancellerInit” and
“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
• 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
•
“dsPIC30F Acoustic Echo Cancellation 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
• Contact Microchip sales for FREE evaluation
samples
∑
+
-
Acoustic Echo
Cancellation
FAR END NEAR END
Far End
Speech
Far End
Speech
Near End
Speech
Near End
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)
DS70123
“dsPIC30F Acoustic Echo Cancellation Library Product Overview”
(Available at: www.microchip.com)