1/18/2006 - Microchip Technology Inc., a leading provider of microcontroller and analog semiconductors, announced a new software library for its 16-bit dsPIC® Digital Signal Controllers (DSCs). The G.168-standard compliant Line Echo Cancellation Library (SW300080-EVAL) offers telecom designers improved integration possibilities and the ability to reduce costs, due to Microchip's unique licensing structure.
The dsPIC DSC's DSP instructions are used extensively in this library. Yet, despite the complex functionality of these libraries, the user interface is simple – just one library file and one header file. This library also leaves sufficient resource headroom to integrate other application requirements, including traditional microcontroller tasks, onto the dsPIC DSC to reduce cost and board space.
Example applications that can benefit from these advanced libraries include: hands-free cell phone kits, speaker phones, intercoms, voice over I/P solutions, teleconferencing systems, and cellular telephony applications.
"Designers today are under pressure to bring products to market quickly and at a lower cost," said Sumit Mitra, vice president of Microchip's Digital Signal Controller Division. "Our C-friendly DSC architecture, coupled with ready-to-use application libraries, reduces development risk and time to market. The low, one-time license cost of our libraries enables a lower overall solution cost."
The G.168 Line Echo Cancellation Library is easily callable via a well-documented Application Programmer's Interface (API). Two user functions are associated with this library, one is for initialization and the second function removes the echo component from a 5-, 10-, or 20-millisecond block of sampled 16-bit speech data. This library is configurable for 16-, 32- or 64-millisecond maximum echo delays (echo tail-lengths). Double-talk detection can be invoked to avoid updating filter coefficients when there is simultaneous speech from both ends of the communication link. As a result, the algorithm functions correctly in the presence of full-duplex communication. Also, an optional non-linear processor can be used to eliminate residual echo, which is typically caused by non-linearity in the echo path.
"Microchip makes it easy for engineers to test drive our advanced application libraries," Mitra said. "The evaluation/development license is downloadable from the Internet for just $5USD. A full license is required only when product shipment begins. We have made it as easy and low risk for our customers as possible."
Line echo cancellation is primarily a time-domain algorithm. The received near-end speech samples are filtered using an adaptive Finite Impulse Response (FIR) filter. The coefficients of this filter are adapted using the Normalized Least Means Square (NLMS) algorithm, so that the filter closely matches the path between the transmitter and receiver. One such example is the path through a telephone hybrid, which is essentially the path traversed by the echo. Echo cancellation of up to 70 dB can be obtained, although echo is typically at least 40 dB.
The G.168 Line Echo Cancellation Library is compatible with Microchip's Noise Suppression and Acoustic Echo Cancellation libraries, which are designed for a similar range of applications.
Availability and Pricing
All licensing options for the G.168 Line Echo Cancellation Library are immediately available. Among these options is a one-year evaluation/development license, which is unaltered from the libraries that are used for production and can be purchased online. The G.168 Line Echo Cancellation Evaluation Library license (SW300080-EVAL) is $5USD. Industry-unique, one-time-fee licensing options are also available for production, which runs counter to the per-unit royalty business model that is common for this class of library. Starting at $2,500USD for 5,000-unit products, the license fee that Microchip charges is attractive to many customers, since it is a fraction of the cost they would incur developing it and assuring compliance themselves.
These one-time fees are based on the estimated lifetime volume of products derived from the design effort that uses the library.
About dsPIC Digital Signal Controllers
The dsPIC digital signal controller is a 16-bit (data) modified Harvard RISC machine that combines the control advantages of a high-performance 16-bit microcontroller with the high computation speed of a fully implemented DSP to produce a tightly coupled single-chip, single-instruction-stream solution for embedded systems design. All dsPIC DSCs integrate Flash program memory and many have specialized codec interface supporting the I2S and AC97 protocols.
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About Microchip Technology
Microchip Technology Inc. (NASDAQ: MCHP) is a leading provider of microcontroller and analog semiconductors, providing low-risk product development, lower total system cost and faster time to market for thousands of diverse customer applications worldwide. Headquartered in Chandler, Arizona, Microchip offers outstanding technical support along with dependable delivery and quality.
The Microchip name and logo, and dsPIC are registered trademarks of Microchip Technology Inc. in the USA and other countries.
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