Software V.18 Modem Standard Negotiation
Mika Kallijärvi · KTH Publication Database DiVA (KTH Royal Institute of Technology) · 2005
During the recent years, the telecommunication infrastructure has been moving slowly from analog techniques towards IP (Internet Protocol) and other digital formats. Along with this change, a new concern, packet loss, has arisen among the earlier problems during text telephone communication. During voice transmission this is not a problem, but in text transmission it leads to bit errors and corrupted characters. One solution to this problem is to change the analog text telephone tones to text, and send it with VoIP (Voice over IP). The characters sent in this fashion can be changed back to the same text telephone tones as transmitted or into some other text telephone standard, if needed. This decoding/encoding of analog- to digital signals is done in a gateway. The purpose of this project is to investigate if it is possible to implement a V.18 modem in Java. This project is divided in two parts: detection of the incoming text telephone signals standard, and decoding of the incoming signals. The part considered in this master thesis is the signal detection part. From the test results for the V.18 modem, we make the conclusion that it is possible to implement a V.18 modem in Java. The different V.18 sub standards, implemented in the modem, can be detected, and the project has resulted in an implementation of a V.18 modem in Java.