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CIT228 chapter 3 RF
CIT228 Chapter 3 RF Fundamentals
| Term | Definition |
|---|---|
| 10’s and 3’s Rules of RF Math | A shortcut for calculating the increase or decrease of RF values. |
| 180 degrees out of phase | Term used to describe two electromagnetic signals that are the complete opposite of each other. |
| absorption | The RF propagation behavior in which an RF signal is assimilated into a material. |
| amperes (amps) | The measure of the flow of electrical current. |
| amplification | An increase in a signal’s strength to achieve gain. |
| amplitude | The magnitude of the change of a wave; measured by how high or how deep the wave is. |
| amplitude modulation (AM) | A modification of an analog electromagnetic wave that changes the amplitude (height) of the wave. |
| amplitude shift keying (ASK) | A modification of a digital electromagnetic wave that changes the amplitude (height) of the wave. |
| analog signal | A continuous signal with no “breaks” in it. |
| attenuation | Loss of signal strength that results in a decrease in the signal’s amplitude. |
| bands | The 450 different sections of the electromagnetic spectrum. |
| carrier | A modified electromagnetic wave that is used to transmit information. Also known as a carrier wave or a carrier signal. |
| corruption | The loss in a signal that occurs when a delayed multipath signal is significantly out-of-phase with the primary signal. |
| current (I) | The flow of electrical energy. |
| cycle | The repetitive movement of an electromagnetic wave that returns back to its starting point. |
| decibel milliwatt (dBm) | The power ratio in decibels (dB) referenced to one milliwatt (mW). |
| decibels (dB) | The measure used to determine RF power gain and loss on a relative scale. |
| delay spread | The difference in time of multipath signals that reach the receiver. |
| diffraction | The RF propagation behavior in which an RF signal bends in response to striking a rough surface. |
| digital signal | A signal that consists of data that is discrete or separate. |
| downfade | The signal loss that occurs when a delayed multipath signal is out-of-phase with the primary signal |
| electromagnetic spectrum | The range of all the different types of electromagnetic waves. |
| electromagnetic wave | A special form of energy that transmits heat and light. |
| Free space path loss (FSPL) | The “natural” loss of signal strength that occurs as a signal travels through space |
| frequency | The number of times that a wave completes a cycle within a given amount time. |
| frequency modulation (FM) | A modification of an analog electromagnetic wave that changes the frequency (number of waves). |
| frequency shift keying (FSK) | A modification of a digital electromagnetic wave that changes the frequency (number of waves). |
| gain | The positive difference in amplitude between two signals. |
| hertz (Hz) | The unit of measurement for electromagnetic frequencies. |
| impedance | The total amount of resistance to the flow of electrical current. |
| Industrial, Scientific and Medical (ISM) | An unlicensed band used for WLANs. |
| in phase | Two electromagnetic signals that have the same peaks and valleys. |
| license-exempt spectrum | Parts of the radio spectrum that are available nationwide to all users without requiring a license. |
| milliwatt (mW) | One thousandth of a watt of power. |
| modulation | The modification of an electromagnetic wave to transmit information; also called keying |
| multipath | The phenomena in which multiple copies of a signal reach the receiver at different times. |
| nanosecond | One billionth of a second. |
| noise | Unwanted interference that impacts an RF signal. |
| nulling | The cancellation of a signal that occurs when a delayed multipath signal is 180 degrees out of phase with the primary signal. |
| ohms | The measure of the restriction of the flow of current. |
| oscillating signal | The visual representation of up-and-down electrical waves. Also called sine wave. |
| out of phase | Term used to describe two electromagnetic signals with peaks and valleys that do not match. |
| phase | The relationship between at least two signals that share the same frequency yet have different starting points. |
| phase modulation (PM) | A modification of an analog electromagnetic wave that changes the starting point of the wave. |
| phase shift keying (PSK) | A modification of a digital electromagnetic wave that changes the starting point of the wave. |
| Receive Signal Strength Indicator (RSSI) | A value intended for internal use by the wireless NIC. |
| reflection | The RF propagation behavior in which an RF signal bounces back after striking a material. |
| refraction | The RF propagation behavior in which an RF signal bends due to a change in atmospheric condition |
| resistance (R) | Measure of the restriction of the flow of electrical current. |
| scattering | The RF propagation behavior in which an RF signal bounces off small objects, such as raindrops. |
| signal-to-noise ratio (SNR) | A ratio of the desired signal to undesired signal in the average power level of a transmission |
| unlicensed bands | Parts of the radio spectrum that are available nationwide to all users without a license |
| Unlicensed National Information Infrastructure (UNII or U-NII) | An unlicensed band used for WLANs. |
| upfade | The gain in a signal that occurs when the delayed multipath signal arrives at the same time as ad is in phase with the primary signal. |
| voltage (V) | Electrical pressure on a wire. |
| volts | The measure of electrical pressure on a wire. |
| watts (W) | A basic unit of power of 1 amp of current that flows at 1 volt. |
| wavelength | The distance between peaks in an electromagnetic wave. |
| wave propagation | The way in which an electromagnetic signal travels. |
Created by:
Leisac
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