Communications Link

Radio performance is defined by two extremes: high power and very low power. On the high RF power side, there is a desire to create a large amount of RF power with the least amount of electrical power from an AC or DC power source. The radio transmitter is often the part of the radio that draws the most energy from the power source, which is of great concern to manufacturers of client devices that run on battery power. The transmitter is also often the most expensive part of the radio: the power amplifiers are the most expensive devices in the unit. In addition, the radio transmitter is potentially the greatest source of interference to itself and to other radios in the vicinity.

On the low RF power side, the radio receiver has to detect very low power signals in a noisy and high interference environment. The communication system does this by adding coding bits and changing modulation to suit the quality of the radio channel. The transmitter, receiver, antennas, and radio channel all play together to allow communications to happen. In this section we examine how each part influences link quality. It all comes together in the last section when we discuss link budgets. There the performance of each element is listed and the robustness of the link is determined.