MA300015 Microchip Technology, MA300015 Datasheet - Page 20

• Manufacturer Part Number: MA300015
• Description: MODULE PLUG-IN DSPIC30F 80QFP
• Manufacturer: Microchip Technology

Specifications of MA300015

• Accessory Type: Plug-in Module (PIM) - dsPIC30F6010A
• Peak Reflow Compatible (260 C): Yes
• Mcu Supported Families: DsPICDEM 1.1 Plus
• Leaded Process Compatible: Yes
• Supported Devices: DsPIC30F6010A
• Development Tool Type: Hardware - Daughter Card
• Silicon Manufacturer: Microchip
• Core Architecture: DsPIC
• Core Sub-architecture: DsPIC30
• Silicon Core Number: DsPIC30F
• Silicon Family Name: DsPIC30F6xxx
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: dsPICDEM Boards (DM300014 or DM300019)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

DS01033C-0
dsPIC® DSC
Line Echo Cancellation Library
Summary
Line echo cancellation eliminates echoes generated in the
electrical path between the transmitter and receiver in a
communication device. Typically, echoes are the result of signal
reflection caused by impedance mismatch in telephone hybrids and
other network components. This “far-end” line echo results in a
perceptible and distracting echo effect at the near end.
Line echo cancellation is useful for telephony applications that
involve transmitting and receiving signals through a telephone
hybrid. It is also useful for digital network applications, such as
cellular telephony and voice-over internet protocol. Though the
dsPIC Digital Signal Controller (DSC) Line Echo Cancellation Library
is targeted to eliminate far-end echo (as demonstrated by the
demo application), the library functions are equally applicable to
eliminating near-end echo.
The dsPIC DSC Line Echo Cancellation Library is written
predominantly in Assembly language and is highly optimized
to make extensive use of the dsPIC DSC instruction set and
advanced addressing modes. The algorithm avoids data overflow.
The library provides a LineEchoCancellerInit function for
initializing the various data structures required by the algorithm
and a LineEchoCanceller function to remove the echo
component from a 10 ms block of sampled 16-bit speech data.
You can easily call both functions through a well-documented
Application Programmer’s Interface (API). Both the processing
frame size and echo tail length (the maximum echo path for which
the algorithm can eliminate the echo) are user-configurable through
constants defined in a header file.
The LineEchoCanceller function is primarily a time domain
algorithm. The received near-end speech samples (typically
sampled from a microphone) are filtered using an adaptive
Finite Impulse Response (FIR) filter. The coefficients of this filter
are adapted using the Normalized Least Mean Square (NLMS)
algorithm, such that the filter closely models the electrical path
between the transmitter and receiver (e.g., the path through a
telephone hybrid), which is essentially the path traversed by the
echo. An optional Double Talk Detection (DTD) feature can be used
to avoid updating the filter coefficients when there is simultaneous
speech from both ends of the communication link (double talk).
As a consequence, the algorithm functions correctly even in the
presence of full-duplex communication. An optional Nonlinear
Processor (NLP) feature can be used to eliminate residual echo.
Sample Rate Conversion
Computational requirements:
Program Flash memory:
RAM:
Note: The user application might require an
additional 1 KB of RAM for data buffering.
Length (ms)
Echo Tail
64
3
16
MIPS
16
10
7
1 MIPS
.6 KB
0.5 KB
Program Flash
Memory (KB)
9
9
9
www.microchip.com
RAM
(KB)
5.5
3.5
.5
Features
Key features of the Line Echo Cancellation Library include:
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Devices Supported
dsPIC30F6014
dsPIC30F6014A
dsPIC30F601
dsPIC30F601A
dsPIC30F5013 (for a max. of 3 ms echo delay)
dsPIC30F5011 (for a max. of 3 ms echo delay)
dsPIC33FXXXGPXXX
Simple user interface – only one library file and one header file
All functions can be called from a C application program
Two user functions:
- LineEchoCancellerInit
- LineEchoCanceller
Full compliance with the Microchip MPLAB® C30 C compiler,
assembler and linker
Functions predominantly written in highly optimized assembly
code that uses DSP instructions and advanced addressing
modes
Echo cancellation for 16, 3 or 64 ms echo delays or tail
lengths (configurable)
Speech processing interval of 5, 10 or 0 ms (configurable)
Fully tested for compliance with ITU-T G.168 specifications for
digital network echo cancellers
Audio Bandwidth: 0 to 4 kHz at 8 kHz sampling rate
Convergence Rate: Up to 60 dB/sec., typically greater than 30
dB/sec.
Echo Cancellation: Up to 70 dB; typically > 40 dB
Can be used together with the dsPIC DSC Noise Suppression
Library, since the same processing block size (10 ms) can be
used
Comprehensive User’s Guide is provided to help the user
understand and implement the library
Demonstration application source code is provided with the
library