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EVRC-B and EVRC-WB
4GV™ Vocoders for cdma2000 Cellular Telephony

The Enhanced Variable Rate Coder (EVRC) is a speech codec used for cellular telephony in cdma2000 systems. EVRC provides excellent speech quality using variable rate coding with 3 possible rates, 8.55, 4.0 and 0.8 kbps. However, the Quality of Service (QoS) in cdma2000 systems can significantly benefit from a codec which allows tradeoffs between voice quality and network capacity, which cannot be achieved efficiently with the EVRC.

An upgrade of the EVRC vocoder, known as EVRC-B, was recently introduced by 3GPP2. The EVRC-B speech codec is based on the 4GV™ concept and is the newest and most advanced speech codec for cellular applications. In addtion to the Relaxed Code Excitation Linear Prediction (RCELP) used by EVRC, EVRC-B uses Prototype Pitch Period (PPP) approach for coding of stationary voice frames and Noise Excitation Linear Prediction (NELP) for efficient coding of unvoiced or noise frames. Using NELP and PPP coding at 2.0 kbps provides EVRC-B with superior flexibility in rate assignment, allowing it to operate at several operating points, each with a different trade-off between speech quality and system capacity. EVRC-B will replace EVRC as the main speech codec for cdma2000 and its first network commercial deployment is planned to start in 2007. A wideband extension, EVRC-WB, will provide speech quality that exceeds regular wireline telephony and its standardization process is planned to be completed at the summer of 2007.

Compandent Inc. intends to offer high-quality EVRC-B package as soon as at the beginning of 2008 and EVRC-WB package during the first half of 2008. The software package will include highly professional and optimized DSP codes with reduced complexity and improved quality for selected platforms. Compandent has been porting EVRC-B and EVRC-WB vocoders to various DSPs by Texas Instruments such as TMS320c54xx, TMS320c55xx, TMS320c64xx, OMAP, and DaVinci, and additional platforms are under consideration.

Compandent implementation of EVRC-B will have:

  • Hand optimized assembly real-time implementation of all algorithm components
  • Extensively analyzed, tested, fixed, and improved real-time implementation
  • C-callable high-level functions
  • Complexity below 30 MIPS
  • Table ROM of 15 Kwords
  • Static (context) RAM of 4 Kwords
  • Dynamic (scratchpad) RAM of 6.5 Kwords
  • Optional components available (customer can select desired combination):
    • EVRC-B encoder and/or decoder
    • EVRC-WB encoder and/or decoder
    • Multi-channel implementation
  • Example of main C program that initializes and runs the EVRC-B vocoder functions
  • "Packetized-Network-Ready" - to maintain high quality even in severe delay and FER conditions
  • Operation mode can be switched on the fly (no need to reload the program to the DSP)
  • Easy and fast test vectors running and verification setup
  • Comprehensive and spectacular Real-Time demo, using DIP-switch control and LEDs indicators
  • Comprehensive and detailed documentation that allows for smooth and easy integration
  • Compandent support and service
  • Very low-cost (about $400) complete DSP development board and tools (CCS) on which Compandent's EVRC-B may run, process the test vectors, and spectacular real-time audio demo

Compandent will also provide EVRC-B related DSP software & hardware in various COTS form factors and platforms, including multi-channel & multi-thread POSIX (Portable Operating System Interface) compliant software running on various platforms such as Unix, Linux, Windows PC, MacOS, etc.. Such implementations are suitable for applications such as PDA, pocket PC, laptop, cell-phones, VoIP.

 

 
 

Customer Reviews
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5 out of 5 stars Great package!!! Very professional!!!
 
Reviewer:   Product Manager - Defense industry (USA)

It was great pleasure doing business and working with you guys! I will be more than happy to support and recommend you. Compandent is a very professional and customer service oriented company. Your MELPe package was so easy to work with. It is a high quality software and has clear documentation. Thanks for everything, and we will support you as best we can.

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5 out of 5 stars Great product! Highly recommended!
Reviewer:   Project Manager - Secure Voice industry (Europe)

Compandent saved us many months of hard work, enabled us short time-to-market, and provided us with critical competitive advantage. Your package was very reliable, and achieved the best quality. The audio demo was very helpful for us in presenting our prototype successfully within a short period of time. It is pleasure working with Compandent. Highly recommended!

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5 out of 5 starsHigh quality software & excellent service!
Reviewer: Engineering Manager - Wireless comm. industry (USA)

Way to go Compandent! We integrated your MELPe into our product almost instantly! The Test Vector and software verification was so easy, we had almost nothing to do, it was all automatically performed, so smooth and easy. Great package which includes everything one may need for using MELPe vocoder in a product. We started with the c54xx, and in the future we will probably use the c55xx as well!

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5 out of 5 stars Excellent MELPe package, and very professional company!
Reviewer: Senior Engineer - NATO vendor (Europe)

Compandent knows the MELPe coder in-and-out! They responded promptly to any question or issue we had, and provided us with the correct answer and solution. Compandent's MELPe is very efficient computationally and memory-wise, which allowed us to run all our software on the c55xx! Definitely the best in the market. We will be more than happy to further recommend you.

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4 out of 5 stars Recommended Good Product

Reviewer: Project Manager - Wireless Device Manufacturer (USA)

This package was easy to test/verify, implement, and use on our platform. Compandent has been extremely helpful and professional with all questions and concerns. One improvement which could be made is related to the memory map. Otherwise, the product has worked exactly as expected.

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