ETSI TS 102 361 sayısal mobil telsiz standardına uyumlu telsizlerin ses kalitesinin ses şiddeti optimizasyonu ve daha iyi ileri hata düzeltme planı kullanılarak arttırılması

Abstract

Voice quality and intelligibility enhancement in digital mobile radios • Performance improvement of advanced multi-band excitation speech codec • Voice volume optimization Block diagram of our work is shown below. Purpose: Our purpose in this work is to enhance voice quality and provide deterministic voice quality in all conditions to increase intelligibility and clearness of the transmitted sound in digital radios. Theory and Methods: We proposed and presented two different improvements that are easy to implement and are isolated from the protocol itself and mainly focused on vocoder utilized in the radios. Primary proposition is to replace the block code based forward error correction with a better error correction schemes like convolution codes. Thus, hybrid of Golay and 5/6 punctured convolution codes are utilized instead of using solely block codes. Other proposed method is based on voice volume optimization using vocoder features like gain parameters. Smoothed and hard limited voice gain parameters offer a clear and understandable voice. Results: In this work, we achieved 2.95 dB coding gain with the help of proposed forward error correction. Also, smooth and clear voice reconstruction is guaranteed by volume optimization and voice gain smoothing. Conclusion: Proposed volume optimization and voice gain balancing help the reconstructed voice to have better dynamic range, increased intelligibility and more natural representation of the source voice. By replacing pure block codes with the hybrid of block and convolutional code, we achieved 2.95 dB coding gain for a BER value of Pb=10-5 with respect to the AMBE FEC. Due to the fact that proposed improvements are vocoder oriented and isolated from protocol, they can be applied to any newer and already manufactured digital mobile radios to enhance voice quality. Not only achieved coding gain offers better communication range and voice quality but also it may extend battery life of radios.