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CIT228 chapter 3 RF

CIT228 Chapter 3 RF Fundamentals

TermDefinition
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