Advanced Multi-Band Excitation
Encyclopedia
Advanced Multi-Band Excitation (AMBE) is a proprietary speech coding
standard developed by Digital Voice Systems, Inc.
-based vocoder
that operates at bitrates
of between 2 and 9.6 kbit/s, and at a sampling rate of 8 kHz in 20-ms frames. The audio data is usually combined with up to 7 bit/s of forward error correction
data, producing a total RF bandwidth of approximately 2250 Hz (compared to 2700–3000 Hz for an analog single sideband transmission). Lost frames can be masked by using the parameters of the previous frame to fill in the gap.
) showed basic advantages of the multi-band representation of speech ("An Approximation to Voice Aperiodicity", IEEE 1968). This work gave a start to development of the "multi-band excitation" method of speech coding, that was patented in 1988 by founders of DVSI as "Multi-Band Excitation" (MBE). All consequent improvements known as Improved Multi-Band Excitation (IMBE), AMBE, AMBE+ and AMBE+2 are based on this MBE method.
and Iridium
satellite telephony
systems and certain channels on XM Satellite Radio
and is the speech coder
for OpenSky Trunked radio system
s.
AMBE is used in D-STAR
amateur radio
digital voice communications. It has met criticism because the nature of its patent
and licensing runs counter to the openness of amateur radio.
The NXDN
digital voice and data protocol uses the AMBE +2 codec. NXDN
is implemented by Icom in the IDAS system and by Kenwood as NEXEDGE.
APCO Project 25 Phase 1 and Phase 2 trunked radio systems also use the AMBE+2 codec.
standard starts at $15,000. For small-scale use and prototyping, the only option is to purchase a dedicated hardware IC from DVSI.
In spite of the fact that a license from DVSI is required in any case (for usage of technology), the software implementations of the MBE vocoders from DSPINI opens wide possibilities for developers and manufacturers of radio and of other equipment where a usage of these vocoders is needed. High quality, high optimization level, high reliability and reasonable prices are basic advantages of these implementations.
Speech coding
Speech coding is the application of data compression of digital audio signals containing speech. Speech coding uses speech-specific parameter estimation using audio signal processing techniques to model the speech signal, combined with generic data compression algorithms to represent the resulting...
standard developed by Digital Voice Systems, Inc.
Overview
AMBE is a codebookCodebook
A codebook is a type of document used for gathering and storing codes. Originally codebooks were often literally books, but today codebook is a byword for the complete record of a series of codes, regardless of physical format.-Cryptography:...
-based vocoder
Vocoder
A vocoder is an analysis/synthesis system, mostly used for speech. In the encoder, the input is passed through a multiband filter, each band is passed through an envelope follower, and the control signals from the envelope followers are communicated to the decoder...
that operates at bitrates
Bit rate
In telecommunications and computing, bit rate is the number of bits that are conveyed or processed per unit of time....
of between 2 and 9.6 kbit/s, and at a sampling rate of 8 kHz in 20-ms frames. The audio data is usually combined with up to 7 bit/s of forward error correction
Forward error correction
In telecommunication, information theory, and coding theory, forward error correction or channel coding is a technique used for controlling errors in data transmission over unreliable or noisy communication channels....
data, producing a total RF bandwidth of approximately 2250 Hz (compared to 2700–3000 Hz for an analog single sideband transmission). Lost frames can be masked by using the parameters of the previous frame to fill in the gap.
History
In 1967 Osamu Fujimura (MITMassachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
) showed basic advantages of the multi-band representation of speech ("An Approximation to Voice Aperiodicity", IEEE 1968). This work gave a start to development of the "multi-band excitation" method of speech coding, that was patented in 1988 by founders of DVSI as "Multi-Band Excitation" (MBE). All consequent improvements known as Improved Multi-Band Excitation (IMBE), AMBE, AMBE+ and AMBE+2 are based on this MBE method.
Usage
It is used by the InmarsatInmarsat
Inmarsat plc is a British satellite telecommunications company, offering global, mobile services. It provides telephony and data services to users worldwide, via portable or mobile terminals which communicate to ground stations through eleven geostationary telecommunications satellites...
and Iridium
Iridium (satellite)
Iridium Communications Inc. is a company, based in McLean, VA, United States which operates the Iridium satellite constellation, a system of 66 active satellites used for worldwide voice and data communication from hand-held satellite phones and other transceiver units...
satellite telephony
Satellite phone
A satellite telephone, satellite phone, or satphone is a type of mobile phone that connects to orbiting satellites instead of terrestrial cell sites...
systems and certain channels on XM Satellite Radio
XM Satellite Radio
XM Satellite Radio is one of two satellite radio services in the United States and Canada, operated by Sirius XM Radio. It provides pay-for-service radio, analogous to cable television. Its service includes 73 different music channels, 39 news, sports, talk and entertainment channels, 21 regional...
and is the speech coder
Speech encoding
Speech coding is the application of data compression of digital audio signals containing speech. Speech coding uses speech-specific parameter estimation using audio signal processing techniques to model the speech signal, combined with generic data compression algorithms to represent the resulting...
for OpenSky Trunked radio system
Trunked radio system
A trunked radio system is a complex type of computer-controlled radio system. Trunked systems use a few channels , and can have virtually unlimited talkgroups. The control channel computer sends packets of data to enable one talkgroup to talk together, regardless of frequency...
s.
AMBE is used in D-STAR
D-STAR
D-STAR is a digital voice and data protocol specification developed as the result of research by the Japan Amateur Radio League to investigate digital technologies for amateur radio...
amateur radio
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...
digital voice communications. It has met criticism because the nature of its patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....
and licensing runs counter to the openness of amateur radio.
The NXDN
NXDN
NXDN is a Common Air Interface technical protocol for mobile communications. It was developed jointly by Icom Incorporated and Kenwood Corporation. was formed in order to promote the NXDN protocol in North and South America...
digital voice and data protocol uses the AMBE +2 codec. NXDN
NXDN
NXDN is a Common Air Interface technical protocol for mobile communications. It was developed jointly by Icom Incorporated and Kenwood Corporation. was formed in order to promote the NXDN protocol in North and South America...
is implemented by Icom in the IDAS system and by Kenwood as NEXEDGE.
APCO Project 25 Phase 1 and Phase 2 trunked radio systems also use the AMBE+2 codec.
Licensing
Use of the AMBE standard requires a license from Digital Voice Systems, Inc. While a licensing fee is due for most codecs, DVSI does not disclose software licensing terms. Anecdotal evidence suggests that licensing fee begin from between $100,000 to $1 million. For purposes of comparison, licensing fees for use of the MP3MP3
MPEG-1 or MPEG-2 Audio Layer III, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression...
standard starts at $15,000. For small-scale use and prototyping, the only option is to purchase a dedicated hardware IC from DVSI.
In spite of the fact that a license from DVSI is required in any case (for usage of technology), the software implementations of the MBE vocoders from DSPINI opens wide possibilities for developers and manufacturers of radio and of other equipment where a usage of these vocoders is needed. High quality, high optimization level, high reliability and reasonable prices are basic advantages of these implementations.
External links
- http://www.dvsinc.com/products/software.htm
- http://www.dspini.com/dspini_imbe.htm
- http://www.dspini.com/dspini_dmr.htm