Speech signal improved transmission system for personal communications

In a personal communication system two essential requirements are better voice quality and reasonable cost of the communication terminal. The paper presents a transmission system that improves the speech signal for communication channel corrupted by impulsive noise. The noise cancellation scheme assumes that the speech signal is framed in 5 ms length windows. For each windows the presence of the noise is detected (using a cyclic redundancy check (CRC) code, overflows detection and the difference between two consecutive speech samples). If a window was determined as a noisy window it is muted by digital attenuation. A real time implementation using the DSP microcomputer ADSP2181 and some experimental results are illustrated. The conclusions are that the noise cancellation scheme works with good results and the system which implements it is realizable at low cost