SPR Vocoders 2400 bps
Classic | Robust
SPR Robust ™ 2400 bps vocoder is based on Sinusoidal Pulsed Representation (SPR) model, providing high quality and other superior characteristics inherent to this model.
Moreover, the vocoder contains Forward Error Correction (FEC) scheme, which is integrated into vocoder on base of "source-channel coding" approach and provides high robustness of the vocoder to channel errors.
We used ITU-T P.50 multilanguage speech base and ITU-T P.862 utility to estimate speech quality.
In clear channel SPR Robust 2400 bps vocoder provides speech quality near to SPR Classic 1200 bps vocoder, conseding to SPR Classic 2400 bps.
However, the vocoder keeps the speech quality in noisy channel, providing high robustness to errors at high BER.
We passed encoded bit streams through AWGN channel simulator with various SNR and estimated quality of decoded speech.
SPR Robust 2400 bps vocoder shows very high robustness to errors, keeping high speech quality in noisy channel with BER up to 5% and even higher.
Time delay is very important characteristic of communication system. Algorithmic delay of vocoder does play determinative role in total delay. Well known, the delay more than 100 ms is not acceptable for normal conversation.
SPR Robust 2400 bps vocoder provides 60 ms delay.
Frame size is 40 ms (320 speech samples).
SPR Robust 2400 bps is very effective vocoder and requires very little of the computing resources.
Less than 23 MIPS for TI's C55xx.
SPR Robust 2400 bps vocoder needs uniquely little memory, providing high rate of the quality/cost.
SPR Robust 2400 bps vocoder is available right now for TI's C55xx DSP and for PC (Win32) platforms and also is available for any other DSP, RISC or general-purpose platform during two-three months.
- SPEECH QUALITY
- ALGORITHMIC DELAY
- COMPUTING COMPLEXITY
- MEMORY USAGE