| When a modem initiates a transmission sequence, it generates a low tone known as a carrier signal. The signal simply is a continuously repeating signal, which by itself conveys no information.However, it serves to inform the device at the opposite end of the telephone circuit that aconnection between the two modems has occurred. The modem that receives the carrier tone thengenerates its own carrier (at a different frequency or pitch from that of the originating device).Then, this new frequency is recognized by the original sending modem, which indicates that aconnection in BOTH directions has been established. This process, commonly referred to as handshaking, is for "full duplex" modems that are capable of transmitting and receiving data simultaneously. |