Modulation Protocols

　　Modulation protocols determine how modems convert digital data into analog signals that can be sent over a phone line. The first modulation protocols were Bell 103 and V.21, which allowed transmission at 300 bps. However, it is impossible to transmit more than 600 bps by converting a single bit into a single signal. By combining digital data into more complex signals, it is possible to transmit at higher speeds. How this is done is determined by other protocols, such as V.32bis and V.34. The suffixes "bis" and "ter" indicate that protocols are further versions of previous protocols. Thus, the 19.2 V.32terbo is an improvement over the 14.4 V.32bis, which is itself an improvement over the 9600 V.32 protocol. The latest modulation protocol is V.34, which allows transmission at 28.8 kbps.