New TWELP Vocoder (600…9600 bps)

DSPINI’s high-quality vocoder provides the best speech quality among competitors today. It has a wide range of bit rates from 600 bps up to 9600 bps and is intended for Digital Radio (HF, UHF, DMR, dPMR, etc.), wire communication, VoIP and other markets.

The vocoder is based on the newest speech coding technology, called “Tri-Wave Excited Linear Prediction”™ (TWELP™), developed by experts of DSPINI.


  • Advance reliable method of Pitch estimation
  • Pitch synchronous analysis
  • Advance tri-wave model of excitation
  • Newest quantization schemes
  • Pitch synchronous synthesis

Although the technology is based on well-known LPC-method, where output speech is gotten by the synthesizing LPC-filter, it is not a variety or combination of well-known speech coding methods, patented comprehensively during last 20-30 years.

TWELP is a unique three-component representation of pitch-synchronous LPC residual that is quantized by unique speech-driven quantizers in conjunction with LPC-parameters.


  • Superiority in speech quality. ITU-T P.50 multi-language speech base and ITU-T P.862 utility were used for objective estimation and pair comparisons by listening were used for subjective estimation.
  • Superiority in non-speech signals (sirens, etc.)
  • High robustness to acoustic noise.
  • High robustness to channel errors, thanks to FEC, integrated using “joint source-channel coding” approach. “Soft Decisions” and “Hard Decisions” from a modem can be used.
  • Automatic Gain Control (AGC), Noise Cancellation for Speech Enhancement (NCSE), Voice Activity Detector (VAD), Tone Relay (transparence) for any single and dual tones.
  • Guarantee of quality thanks to accurate testing and methods of quality control. Reliable support.


  • Any platforms (DSP, RISC or general-purposes) are available for porting.
  • Integrated Circuit (Chip). TWELP 2400/3600 bps vocoder is available also as specialized chip (IC) from CML Microcircuits.
  • One license. No third-party IP holders.
  • Related software: Linear and Acoustic Echo Cancellers (LEC and AEC), Multi-Channel Noise Cancellers, modems for radio and wire channels for any bit rates.


Varies. Check website and contact to find out current availability.


Communications & Telecom, Military, Security, Wireless


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