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75 Cards in this Set

  • Front
  • Back
Spectrum Analyzer
Magnitude (power) on y -axis
Frequency (Hz) on x- axis
OSI Model
7 - Application
6 - Presentation
5 - Session
4 - Transport
3 - Network
2 - Data Link
1 - Physical
Physical Layer Technology?
OFDM, Ethernet Hubs. FHSS
Data Link Layer Technology
MAC addresses, 802.11, 802.3
Network
IP, Routers, packet filters
Transport
TCP, UDP
Session
RCP, Some parts of TCP
Presentation
Encryption Protocols, SSL, HTTPS
Application
Most Firewalls, FTP, POP3, HTTP
Hook batteries in parallel
Increases Current
Hook batteries in Series
Increases Voltage
AC
Electric Current in which direction of flow reverses at frequent regular intervals
DC
Electric Current that flows in one direction
Amp
Unit of electrical current going through a wire
Watt
One Amp under the pressure of one volt
Volt
Unit of force that causes electrons to flow through a wire
Power = Watts (W) =
V(volts) X A(Amps)

1000W = 1kW
Series Wiring
Positive Terminal to Negative Terminal

Increases Voltage
Parallel Wiring
Positive to Postitive

Increases Amps
Loads in Series are Bad!
Because they cause a additive voltage drop. If one light burns out, the other receives no power
Loads in Parallel are Good!
Voltage remains constant. Each load can be controlled individually.
Frequency
# of cycles per second. Frequency is measured in Hz, one complete cycle.
Freq Ranges
HF
VHF
HF: 3- 30 MHz (Shortwave)
VHF : 30 - 300 MHz (Radio, FM Broadcasting)
Freq Ranges
UHF
UHF : 300 MHz - 3 GHz (Cordless Telephones, GPS)
Freq Ranges
SHF
EHF
SHF : 3 - 30 GHz (WiFi, Satellites)
EHF : 30 - 300 GHz (Microwave)
GPRS
General Packet Radio Service
Works with GSM to enable mobile devices to send Packets. Users get assigned a Uplink/Downlink Freq.
Rescue 21 has:
* portable radio towers
* fully housed communications shelters
* satellite backup communications
* remotely located watchstander equipment
* remotely located backroom operating equipment
What is the definition of Gain
Signal going into the device is smaller then the device going out
What is a amplifier
A device which causes Gain
Describe an impedance matching circuit.
A circuit capable of changing the impedance with different values for incoming and outgoing impedance.
What is the L-Band
1-2 GHz , GPS Band!
What’s the relation between dB and change of signal?
+3 dB is 2 times bigger, +10 dB is 10 times bigger
What is a dB
A Comparative Logarithmic Power Measurement
what is dBm
It is a absolute power measurement in milliwatts
what is dBi
It is a measurement against a isotropic radiator
what is dBd
Measurement against a dipole antenna,
0 dBd = ? dBi
2.14
How many bels in a decibel
1/10 of a bel
RF signals experience ? decay as they travel
logarithmic. They lose power exponentially
How do you convert mW to a dBm measurement?
10 X log10(Power in mW)
Noise Floor
The level of Background Noise
SNR
Power of your RF Signal relative to the power level of the noise floor
RSSI
Arbitrary level of received signal strength
Link Budget
A accounting of all components of power, gain, loss, receiver sensitivity, and fade margin
Fade Margin
The amount by which a received signal level may be reduced without causing system performance to fall below a specified threshold value.
Multipath
propagation phenomenon that results in radio signals' reaching the receiving antenna by two or more paths
Fresnel Zone
LOS Zone that is blocked by the bulge of the earth
Loss : Reflection
Signal bounces off of a surface and changes direction
Loss : Refraction
Occurs when a RF Signal changes speed and is bent while moving between different densities
Loss : Diffraction
Change in direction or intensity of a wave as it passes by the edge of a obstacle
Loss : Scattering
RF Signal strikes a uneven surface and spreads so the resulting signals are less significant then the original signal
Loss : Absorption
Material absorbs the signal
Impedance mismatching
Impedance bridging is unsuitable for RF connections because it causes power to be reflected back to the source from the boundary between the high impedance and the low impedance. The reflection creates a standing wave, which leads to further power waste. In these systems, impedance matching is essential.
What is impedance
??
VSWR
A Measurement of mismatched impedance in a RF System, usually a ratio.
Return Loss
Backward reflection of the signal toward the transmitter
Free Space Path Loss
Weakening of RF Signal due to broadening of the wave front.
sideband
a band of frequencies higher than or lower than the carrier frequency, containing power as a result of the modulation process.
How fast do radio waves travel?
The speed is 300,000,000 meters per second
or 186,000 miles per second or The Speed of Light.
A Transmission Lines has what two things?
Antenna Portion and a Ground Portion.
Every antenna has how many poles?
Antenna and the ground plane
How do you calculate the length of the antenna
234 / Freq in MHz = # of ft to get a 1/4 wavelength
Polarization of the Antenna
Horizontal sends waves Vertical, Vertical sends waves Horizontal. Think of a bow and a arrow
Factors determining propagation of radio signal
Frequency, Polarization of Antenna, Height of Antenna
What is more dangerous to humans, the volts or the Amps?
The Amps is what will hurt you
What is a vector?

What is a scalar?
Vector: Magnitude + Direction

Scalar: Magnitude
Series Circuit
One or more resistors (loads) connected to a voltage source with one path for Electron Flow
Parallel Circuit
Two or more different paths for the current to flow
VSAT
Very Small Aperture Terminal
KU Band
Satellite Band
Downlink: 11.7-12.7 GHz

Uplink: 14 - 14.5 GHz
HF Field Expedient Antenna

Ground:
Vertical Wire
Sloping Wire (vary angle )

Antenna is 1/4 or freq wavelength
HF Field Expedient Antenna

Sky:
1/2 Wave Length Horizontal Dipole

Ins-(-)--1/4---Cobrahead---1/4-(+)--Ins.
Ohm
Volt
Amp
Watts(Power)
A measurement of Resistance
Pressure
Current/Electron Flow
Volts X Amps
OHM's Law
It takes one volt of electrical pressure to push one amp of electrical current through a resistance of one ohm
Volts = ?
Current = ?
Current X Resistance
Voltage / Resistance