New DSP Technology Provides Superior Characteristics in Low-Bitrate Speech Coding
|DSP Innovations Inc.|
Sinusoidal Pulsed Representation (SPR) is innovative technology of the high quality speech coding for wide range of the low bit rates from 4800 bps down to 600 bps.
New technology is based on advanced parametric model of the speech synthesis where speech is formed as a mixture of three components:
- "fundamental frequency" harmonics,
- noise-like signal,
- aperiodic impulses.
Unlike well-known speech models, for example MELPe, where speech is presented as a mixture of two (voiced and unvoiced) components, SPR model includes a third component like used in popular Multi-Pulsed Excitation model. This representation allows to synthesize correctly all speech sounds, including complex speech transients with aperiodic vibration of vocal cords. All parameters of the new model are found on "analysis by synthesis" base, providing a very high quality of recovered speech.
SPR Classic and SPR Robust are two lines of proprietary "royalty free" innovative vocoders based on the new technology from DSP Innovations, Inc. (www.dspini.com/dspini_classic_robust.htm)
SPR Classic vocoders provide new level of speech quality, which was unachievable earlier for such low bit rates. These vocoders are suitable ideally for voice storage or voice communications through errorless channels.
Unlike SPR Classic vocoders, SPR Robust vocoders include Forward Error Correction (FEC) scheme which is integrated into vocoders, using "source-channel coding" method and provides very high robustness of the vocoders to channel errors. These vocoders are suitable for voice communications through noisy channels, including radio channels with very low SNR (signal to noise ratio). For example, high speech quality and robustness, low requirements to resources, low cost and royalty-freedom of the SPR Robust 3600 bps vocoder make this vocoder suitable very well for digital Private Mobile Radio (dPMR) European standard ETSI TS 102 490.
DSP Innovations Inc. (DSPINI), a supplier of DSP-software and engineering services, was founded in 2007, having united the best Russian scientists, software engineers and hardware designers who have great experience in DSP and development of various telecommunication equipment. The mainstream of the company is speech technologies and voice communication: innovative methods of speech coding, speech enhancement (noise and echo cancelling, spectrum equalization, etc.), advanced methods of "source-channel coding". Proprietary “royalty-free” and standard vocoders from DSPINI have superior characteristics, operate in range from 300 bps up to 64 kbps bit rates and are used in: secure voice, software defined radio, wireless, VoIP, voice storage, etc.
Having great experience in development of math intensive algorithms and software, in hardware design, production, testing and exploitation of various radio and telecommunication equipment, DSPINI’s team uses strong background to provide to each customer the most advantageous solution.
Source: DSP Innovations Inc.