AMBE-4020™ Half-Duplex and
AMBE-4020™ Full-Duplex
Vocoder Chips


Digital Voice System's AMBE-4020™ Vocoder Chips are an extremely flexible, low cost, voice compression solution that are ideal for commercial, consumer, and military mobile radio communication applications. As a new addition to DVSI's family of vocoder chips, the Half-Duplex AMBE-4020™ and the AMBE-4020™ Full-Duplex Vocoder Chips boast a built-in high performance ADC/DAC in a small footprint design that makes them easy to integrate and require minimal power.


The AMBE-4020™ Vocoder Chips use proven technology to deliver a level of performance and reliability typically associated only with customized ASICs, but without the associated risks and high development costs. With small quantity, off-the-shelf availability and no licensing fees or royalties, engineers and original equipment manufacturers are able to efficiently design and affordably produce high performance, narrowband, low volume communication equipment.

The AMBE-4020™ Vocoder Chips implement DVSI's patented AMBE+2™ Voice Compression Algorithm that can operate at virtually any data rate from 2.0 to 9.6 kbps. The built-in FEC combines block and convolution codes with up to four bits of Viterbi soft decision decoding.

With this high degree of flexibility, the user can optimize speech and Forward Error Correction (FEC) rates to provide exceptional robustness to background noise and intelligible speech in degraded channel conditions, even with bit errors (BER) of up to 20%. This level of performance can lead to the successful development and deployment of wireless communication systems in the most demanding environments.

The AMBE-4020™ Vocoder Chips offer several features in addition to the built-in ADC/DAC, such as an interface for low-cost digital microphone, automatic Voice/Silence Detection (VAD), adaptive comfort noise insertion (CNI), DTMF and Call Progress Tone detection/regeneration, and low power modes. Additionally, AMBE-4020™ Vocoder Chips include serial interfaces for vocoder configuration, status information, as well as, transferring speech and compressed data bits to/from the chip's encoder and decoder. The numerous advanced design features not only ease the design constraints of half-duplex systems, but also reduces additional hardware requirements.

The AMBE-4020™ vocoder chip offers our customers tremendous flexibility in the design of high performance, narrowband, push-to-talk equipment. This small, low-cost platform enables engineers and Original Equipment Manufacturers to efficiently produce mobile radio and other wireless communication solutions where bandwidth is at a premium and high quality voice is crucial to success.

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The AMBE-4020™ vocoder chip's low-power requirements allows it to be easily incorporated into base band circuit where ultra-low-power consumption is critical. In a typical push-to-talk communication system AMBE-4020™ vocoder chip's uses 28mW during encode, 18 mW for decode, <15uW in sleep mode. The chip's small form factor (80-pin LQFP) provides design flexibility in circuit boards where board real estate is at a premium.

As another member DVSI's family of advanced voice compression products, the AMBE-4020™ has interoperable modes that provide a seamless migration path from systems already using DVSI's AMBE-3000™ , AMBE-2000™ and AMBE-1000™ Vocoder Chips.

DVSI Vocoders Interoperable with the AMBE-4020™

AMBE-2000™ Chip Rates YES
AMBE-3000™ Chip Rates YES*
APCO Project 25 Half Rate NO
APCO Project 25 Full Rate NO
TerreStar NO
MexSat NO
GlobalStar NO

(* NOTE: The following AMBE-3000™ built-in rates are not supported: 33-37, 47, and 51-55. As a result, MotoTRBO, DMR, dPMR, NXDN and APCO Project 25 Half Rate are not supported as indicted above.)
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The value of DVSI's AMBE® Voice Compression Technology goes beyond low bit rate and voice quality. It has been thoroughly evaluated and tested by international manufacturers under various conditions using a variety of languages. This assures the user is getting the best vocoder available and makes the DVSI vocoder the logical choice without the need for additional comparison tests. Plus the fact, that DVSI's Voice Compression technology has been implemented worldwide for more than 25 years, delivers the added security of a field proven technology that can play a key role in making any communication system an overall success.

High Quality Performance

Design Flexibility/Low Cost Integration


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Download the AMBE-4020™ Manual