TABLE OF CONTENTS More and more communication is becoming digital. Communication between computers is naturally digital, but current voice and video communication systems also typically transmit in digital form.
Digital communication is required for the use of high-security encryption and for some types of spread spectrum transmission. Digital signals can be efficiently multiplexed and routed to one or many intended recipients, and can be protected against intentional or unintentional interference by use of various error detection and correction approaches.
The good news about digital communication is that with reasonable care, the signal quality can be preserved through many changes of format, sequential link transmissions, and storage/retrieval cycles. The bad news is that once the signal is digitized, the output signal quality does not get any better through downstream processing although processing can optimize the signal format and presentation characteristics for specific applications.
A digital signal represents some information in digital form. Typically, this is in binary form a series of "ones" and "zeros." Some transmitted information is inherently digital, for example when two computers communicate. When you hit a key on your PC keyboard, the computer generates an 8-bit signal to capture your keystroke. However, analog data is also converted to digital form for transmission. Typical digitized analog data includes voice signals, video signals (television, infrared scanner output or radar output) and instrumentation signals (temperature, voltage, angular position).
Digitization is a complex field which we cover here at a very rudimentary level to support later propagation and EW...
