![]() Either Eric and Sierra need to move closer together, or Sierra needs to speak louder. In this case, the interference of the baby has made it impossible to effectively support communications. If their baby, Madison, is crying loudly, Eric might miss a few words. Sierra, acting as the transmitter, is speaking just loud enough for Eric, the receiver, to hear every word. For illustration, imagine two people, Eric and Sierra, whom are 20 feet apart and trying to carry on a conversation. The ability of the receiver to make sense of the signal, however, depends on the presence of other nearby RF signals. ![]() Therefore, the signal must have enough power to reach the desired distance at a signal level acceptable that the receiver needs. The atmosphere causes the modulated signal to attenuate exponentially as the signal propagates farther away from the antenna. In an open environment, one clear of obstacles, the RF signals experience what engineers call free-space loss, which is a form of attenuation. If the range between the sender and receiver increases, the signal amplitude declines exponentially. As the power increases, so does the range.Īs a radio signal propagates through the air, it experiences a loss in amplitude. Power, in terms of electromagnetic signals, represents the amount of energy necessary to push the signal over a particular distance. The measure for amplitude is generally power, which is analogous to the amount of effort a person needs to exert to ride a bicycle over a specific distance. The amplitude indicates the strength of the RF signal. Amplitude, Frequency, and Phase Are Basic Elements of RF Signal These attributes vary in time in order to represent information.įigure 3-2. ![]() As shown in Figure 3-2, the signal that feeds the antenna has an amplitude, frequency, and phase. The RF signal propagates between the sending and receiving stations' antennae. In fact, RF signals are the most common means for carrying data over a wireless network. They provide the means for carrying music to FM radios and video to televisions. RF signals have been in use for many years. An RF signal is an electromagnetic wave that communications systems use to transport information through air from one point to another.
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