Cwna Chapter 3 Radio Frequency Components, Measurements, And Mathematics

Front 1

The initial component in the creation of the wireless medium. This component's job is to begin the RF communication.

Back 1

Transmitter

Front 2

The transmitter takes the data provided and modifies the AC signal by using a ____________ technique to encode the data into the signal.

Back 2

Modulation

Front 3

The transmitter is responsible for determining the original transmission amplitude, or what is more commonly referred to as the _______ _______.

Back 3

power level

Front 4

When this is connected to the transmitter, it collects the AC signal that it receives from the transmitter and directs, or radiates, the RF waves away form it in a pattern specific to its type.

Back 4

antenna

Front 5

The ________ converts the AC signal to bits and bytes.

Back 5

receiver

Front 6

The term used to describe a signal that is radiated equally in all directions. The sun is one of the best examples of this term as it generates equal amounts of energy in all directions.

Back 6

isotropic radiator

Front 7

The final component in the wireless medium. This takes the carrier signal that is taken or given from the antenna and translates the modulated signals into 1s and 0s.

Back 7

receiver

Front 8

A device that intentionally generates and emits radio frequency energy by radiation or induction. A device that is specifically designed to generate RF.

Back 8

Intentional Radiator (IR)

Front 9

The highest RF signal strength that is transmitted from a particular antenna.

Back 9

Equivalent isotropically radiated power (EIRP)

Front 10

The transmit power of most indoor WLAN radios varies in range between _______ and _______.

Back 10

1 mW; 100 mW

Front 11

Units of Power (absolute)

Back 11

watt (W)
miliwatt (mW)
decibels relative to 1 milliwatt (dBm)

Front 12

Units of comparison (relative)

Back 12

decibel (dB)

decibels relative to an isotropic radiator (dBi)

decibels relative to a half-wave dipole antenna (dBd)

Front 13

The basic unit of power. One _____ is equal to 1 ampere (amp) of current flowing at 1 volt.

Back 13

watt

Front 14

A unit of power that is 1/1,000 of a watt. Most indoor 802.11 equipment transmitts at power levels between 1 _____ and 100 ____.

Back 14

milliwatt (mW)

Front 15

A unit of comparison, used to represent a difference between two values, relative expression and a measurement of change in power. Most often used to compare the difference or loss between the EIRP output of a transmitter's antenna and the amount of power received by the receiver's antenna.

Back 15

decibel (dB)

Front 16

A _______ is equal to 1/10 of a bel.

Back 16

decibel

Front 17

A relative measurement and a measurement of antenna gain. Its value is measured at the strongest point, or the focus point, of the antenna signal.

Back 17

decibels isotropic (dBi)

Front 18

A unit of comparison or relative measurement that is the increase in gain of an antenna when it is compared to the signal of a dipole antenna.

Back 18

decibels dipole (dBd)

Front 19

A unit of power that is used to compare a signal to 1 milliwatt of power.

Back 19

decibels relative to 1 milliwatt (dBm)

Front 20

The 6 dB rule states that...

Back 20

a +6dB change in signal will double the usable distance of a signal and a -6dB change in signal will halve the usable distance of a signal.

Front 21

This law states that the change in power is equal to 1 divided by the square of the change in distance.

Back 21

Inverse Square Law

Front 22

In the rules of 10s and 3s, the 3s state:

Back 22

For every 3 dB of gain, double the abolute power (mW)

For every 3 dB of loss, halve the absolute power (mW)

3 dB gain = mW * 2

3 dB loss = mW / 2

Front 23

In the rules of 10s and 3s, the 10s state:

Back 23

For every 10 dB gain, multiply the absolute power (mW) by a factor of 10.

For every 10 dB loss, divide the absolute power (mW) by a factor of 10.

10 dB gain = mW * 10

10 dB loss = mW / 10

Front 24

The ambient or background level of radio energy on a specific channel. This can include modulated or encoded bits from nearby 802.11 devices such as microwaves, Bluetooth devices, portable telephones, etc.

Back 24

Noise Floor

Front 25

The difference in decibles between the received signal and the background noise level .

Back 25

Signal to Noise Ratio (SNR)

Front 26

If the amplitude of the noise floor is too close to the amplitude of the received signal, what will likely occur and results in layer 2 retransmissions?

Back 26

data corruption

Front 27

_______ _______ refers to the power level of an RF signal required to be successfully rceived by the receiver radio. The lower the poser level that the reciver can successfully process, the better the ________ ______.

Back 27

Receive sensitivity

Front 28

A metric used by 802.11 radios to measure amplitude (signal strength).

Back 28

received signal strength indicator (RSSI)

Front 29

The _____ ______ is a measurement of what might affect coding techniaques, sucha the Barker code or Complementary Code Keying (CCK), which rlates to the transmission speed. The ______ ______, which is a measure of pseudonoise code correlation qaulity received by a radio.

Back 29

signal quality (SQ)

Front 30

______ ______ calculations include original transmit gain, passive antenna gain, and active gain from RF amplifiers.

Back 30

Link budget

Front 31

What term is the sum of all the planned and expected gains and losses from the transmitting radio, through the RF medium, to the receiver radio?

Back 31

Link budget

Front 32

A level of desired signal above what is required. If a receiver has a receive sensitivity of -80 dBm, a transmission will be successful as long as the signal received is greater than -80 dBm.

Back 32

Fade margin

Front 33

This functional measurement is the difference between the actual received signal and the signal necessary for reliable communications.

Back 33

system operating margin (SOM)

After the RF link has been installed, it is important to measure the link to see how much buffer there actually is.

Front 34

When calculating IR power, The IR consist of all the components from the transmitter to the antenna but exclude the ______.

Back 34

antenna

Front 35

When the ________ receives the data from the computer, it begins generating an AC (alternating current) signal.

Back 35

Transmitter

Front 36

As the distance from the source of a signal doubles, the energy is spread out over four times the area, resulting in one-fourth of the original intensity of the signal. What term describes the rate at which this expansion happens.

Back 36

Inverse square law