03

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Flashcards by rowelld, updated more than 1 year ago
rowelld
Created by rowelld over 5 years ago
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Description

cwna CWNA Flashcards on 03, created by rowelld on 09/06/2015.

Resource summary

Question Answer
Transmitter Generates AC signal Takes data and modifies the AC signal using a modulation technique Responsible for determining the transmission amplitude
Antenna Receives AC signal from transmitter and radiates RF waves or receives RF waves
Intentional Radiator (IR) Intentionally generates radio frequency
EIRP Equivalent Isotropically Radiated Power Highest RF signal strength transmitted from an antenna
Units of absolute power watt (W) milliwatt (mW) decibels relative to 1 mW (dBm)
Units of comparison (relative) decibel (dB) decibels relative to an isotropic radiator (dBi) decibels relative to a half-wave dipole antenna (dBd)
Watt 1 watt = 1 amp of current flowing at 1 volt Amount of watts generated is = to volts * amps
Milliwatt mW Unit of power, 1/1000 of a watt
Decibel dB Unit of comparison Represents a difference between two values / measurement of change in power Often used to compare power of two transmitters or difference or loss between EIRP output of a transmitter's antenna
dBi Gain/increase/power from an antenna when compared to an isotropic radiator Relative measurement of antenna gain
dBd Describes antenna gain in decibels dipole Increase in gain compared to signal of a dipole antenna
dBm Comparison of signal to 1 mW Because of FSPL, received signals will always measure below 1 mW
Rules of 10s and 3s For every 3 dB gain (relative), double absolute power (mW) For every 3 dB of loss (relative), halve absolute power (mW) For every 10 dB gain (relative), multiply absolute power (mW) by factor of 10 For every 10 dB loss (relative), divide absolute power (mW) by factor of 10
What is noise floor Ambient or background level of radio energy on a specific channel
What is SNR Signal-to-noise ratio Difference in decibels between received signal and background noise level (noise floor)
What is RSSI Received Signal Strength Indicator Power level of signal required to be successfully received by the receiver radio Relative metric used by radios to measure signal strength. Expressed in absolute dBm values
What is link budget Sum of all planned and expected gains and losses from the transmitting radio through the RF medium to the receiver radio
What is fade margin Level of desired signal above what is required
What is System Operating Margin Planning for the buffer. Difference between actual received signal and signal necessary for reliable communications
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