At any instant in time, the beam takes on an analog value of intensity to produce the desired brightness at that point on the screen. Digital Signals A. Digital Data Signaling - transmission of electromagnetic pulses that represent the two binary digits 1 and 2. Binary info is generated by terminals, computers, and other data processing equipment and then converted inot digital voltage pulses for transmission. Text characters are represented by a sequence of bits. Each character is represented by a unique 7-bit binary code.
Received signals differ from transmitted ones, due to transmission impairments.
For analog signals, random modifications degrade the signal quality, and for digital signals, bit errors are introduced. For c., which is particularly a problem for analog signals, techniques are available for equalizing attenuation across a band of frequencies. B. Delay distortion - occurs in transmission cables but not when signals are transmitted through the air by means of antennas. Caused by the fact that the velocity of propagation of a signal through a cable is different for different cables. This is a limitation to data rate for digital data.