RF theory Flashcards
(31 cards)
denotes an absolute power level measured in decibels and referenced to 1 milliwatt;
the amount of power that an antenna or amplifier is able to produce, or how much signal is present at a site;
If you need to convert W to mW you just move the decimal 3 positions to the right. 10W = 10,000mW
Decibel-milliwatts dBm
According to the Rule of 3 if you increase the dBm by 3 you ________ your power
double
Rule of three states that if for every loss/gain of 3dBm you multiply your power by __
2
According to the rule of 10 if you multiply your power by 10 you _________ to your dBm?
add 10
Rule of ten states that if for every loss/gain of 10dBm you multiply your power by __
10
Electronics measure power with what unit of measurement?
dBm
primary signal type used for almost all communication, including radio, wifi, and cellular signal
sine waves
4 types of waves
sine (sinusoidal), square, triangular, saw tooth
_____ waves are generally used for digital signals;
cable tv, HDMI, MIDI, serial connections
square waves
____ waves have been used with some optical signals
triangular
“pure wave” of a constant frequency;
contains no information;
one frequency/tone/pitch that doesn’t change, like a hearing test;
higher than any other signals that will be used to add data
carrier wave
transmits data through space, or across a medium, by adding another signal called a _____ signal
carrier wave; modulating
signal that holds the information; signal sent thru a modulator to attach data onto a signal that is sent across the airwaves to a destination
modulating signal
process of changing or combining a carrier wave and a modulating signal;
this signal is sent at a higher frequency, which means it doesnt travel as far, but it travels with high bandwidth and better throughput;
once signal reaches its destination, it is demodulated to retrieve the data
modulation
amplitude fluctuates as the modulating wave combines with the carrier wave;
frequency of the carrier wave stays constant
AM amplitude modulation
frequency of the carrier wave is changed in accordance to the modulating signal;
As the amplitude is higher in the modulating signal the frequency becomes higher on the modulated wave
FM frequency modulation
a measurement of the amount of resistance between two points in an electrical circuit;
unit of measurement is Ohms
-how much energy loss you will have to ensure adequate electricity makes it through to run your device
-the more resistance the more heat, and cooling must be setup to counter this
impedance
what occurs when two devices that are connected have different impedances, which results in inefficient power transfer or signal reflection
impedence mismatch
low impedence;
copper, gold, silver, aluminum, tap water
conductor
very high resistance;
Rubber, Plastic, Paper and Distilled Water
insulator
impedence is bad. If you have a transmitter it will be connected to an antenna to transmit a signal. You must compare the impedance level of both devices to see how well they match up. this comparison is called ____, and must be as low as possible. 1 means they perfectly match up, while higher viswer means signal strength is lower with a higher chance of signal reflection. if signal is too strong, it damages the transmiter, as it’s designed to transmit not receive
VSWR/viz-wer
system that allows communication in only one direction;
transmitter never receives a response from the receiver;
ex: radio, tv broadcast
simplex
Data flows back and forth, but only in one direction at a time because all transmitters share the same channel/frequency;
each participant can transmit and receive, but only one station can transmit at a time;
Tactical Radios, Walkie-Talkies, WIFI
Half-duplex
Tactical Radios, Walkie-Talkies, WIFI
Half-duplex
