DATA TRANSMISSION.

Abstract

The article considers the following factors involved in data transmission: modulation, bandwidth, pulse distortion, signal-to-noise ratio, and bit error rate. Modems are explained; these devices convert dc pulses supplied by a computer or supervisory control into modulated ac for the communication channel (at the transmitter) and re-convert the modulated-ac to dc pulses (at the receiver). The significance of band rate when considering a communication channel is explained. The limiting effect of channel bandwidth on data transmission capability and the consequent use of frequency division multiplexing are described. General guidelines are given for the signal-to-noise, ratio (S/N) which pipeline operations can tolerate, which is considerably higher than for other data communication systems. In addition, it is suggested that if the S/N is excessive, reducing the data rate and providing filters for the modems should improve the S/N.