Unit Testing of ETSI Cellular Text Telephone Modem

摘要

A special type of telephone is required for the deaf or hard of hearing or people with impaired speech. The error rates required for the transmission of text are not satisfactory in modern cellular telephone systems. For speech signals the encoding and compression techniques are optimized. However the modem signals distort too much. The cellular text telephone modem offers an improved solution having modulation techniques with FEC, interleaving and synchronization. The CTM adapter is directly adapted into the mobile subscriber phone. This includes a transmitter and a receiver respectively. The incoming text characters are recognized and converted by a CTM transmitter into a compatible signal that can be sent over a voice channel. Source code from ETSI is properly compiled and executed to ensure correctness of working.