| 摘要 |
<p>A method of automatic half-duplex communication switched between a first and second unit via a switched telephone network line. At least one matching signal stream exchange is used for half-duplex communication, each matching signal stream begins with an unmodulated carrier signal having a given nominal length and a first carrier frequency, and each unit is arranged to sense said unmodulated carrier signal frequency and exchange with the other unit two timing signal streams to enable communication in a first mode. The method is useful in multimode 'Minitel' R V23/V27ter/V29 and videotext access bridge (PAVI) V27ter/V29.</p> |
