An Experiment of Data Transfer with ITU-T V.34 MODEM on a Telephone Line and Enhance the Communication Efficiency

V.34 28800bpsのモデムを用いた伝送実験によって以下のことが判った。 (1)本実験における伝送エラーは皆無であった。 (2)伝送効率は9600bpsを基準とすれば,非圧縮時にYMODEM-gで503%, ZMODEMで413%である。また,圧縮時の伝送効率は,YMODEM-gで884%, ZMODEMで766%である。 (3)データを圧縮して伝送した場合,非圧縮時と比べ平均2倍程度の伝送効率の向上が確保される。従って通信コストは2分の1に低減することができる。 (4)伝送プロトコルは回線の状態が良好な場合YMODEM-g,再送要求の多発する回線ではZMODEMを使用する方が通信効率の良いデータ伝送を行うことができる。 (5)その他データ長の長いファイルは,伝送中にフロー制御のため伝送を一時中断して伝送効率の低下を招くことから,DTEや通信ソフトは,高速データ通信に対応したものを使用することが必要である。We often heard a topic related to the Internet recently. Several millions of people are communicating by a personal computer in Japan. They are eager to join in the Internet with high speed modem or INS64 by public telephone line. Because, many Internet providers have been establishing for above users all over our country. Accordingly, we carried out a transmission experiment of ITU-T V.34 28800bps MODEM that will be used by many users. They can connect with the Internet by dial up IP even stay at home. Four kinds of files were used in this experiment. There are English text file, Japanese text file, NOAA APT image file and MS-DOS execute file. Also compressed files made up from each uncompressed files. The purpose of this research is to certify the transfer rate and to improve the communication efficiency by the V.34 28800bps MODEM. Results were as follows; 1) No transmission error was found during the experiment. 2) An average communication efficiency of none compression file had about 413% with ZMODEM protocol and 503% with YMODEM-g protocol. (The numerical value compared with communication speed 9600bps.) 3) The communication efficiency of compression file was about 766% with ZMODEM protocol and 884% with YMODEM-g. Thus we can get the best efficiency by using the YMODEM-g protocol. 4) Communication efficiency of a data transmission by compression file is about 200% of which by none compression file. 5) The dial up IP for the Internet connected good condition by V.34 28800bps on the public telephone line