An alternative form of signal transmission is that of sequence of numbers, each number reprcsenting the signal magnitude at instant of time. Read More

Digital signal :- Bit rate- number of bit per second (bps).   Bit interval- duration of one bit.

An significant disadvantage of biphase technique is that it requires at least one transition per bit time and may have as many as two transitions.

Telecommunication devices and computers use signals to represent data. These signals are transmitted from one device to another in the form of elelectromagnetic energy.

It follows the contour of the earth.
It can propagate considerable distances, well over the visual horizon.<