VHF Communications Flashcards
VHF Communications is found under what ATA?
23-10
VHF Communications, or in short VHF COM, for aviation is found in the frequency range from:
118.00 - 136.99163 MHz
VHF waves propagate as:
Space waves
VHF transmissions and reception is over a relatively ______ range.
short
A fairly recent change to the VHF spectrum for aviation was that the subdivision for channels now has what spacing?
8.33 KHz spacing
What VHF channel is reserved for emergencies?
121.5 MHz
(1215 if you wanna stay alive)
What VHF channel is reserved for flight testing?
123.4 MHz is reserved for flight testing
Most flight schools use 123.3 MHz
(Testing.. Testing… 123)
Aviation VHF communication systems are Amplitude Modulated and transmit between what wattage?
One (1) and Fifty (50) Watts
Some maintenance data states the VHF Comms range as 118- 136.992 MHz. The actual range is:
118.00 to 136.99163
What type of antenna is used for VHF communications?
Marconi type
May be mounted on the top or bottom of the airframe
VHF antennas can be one of two designs, which are:
Whip or Blade
How many VHF COM antennas are there?
typically 3
Whip antennas are used on slower aircraft while blade types are normally used on high-speed aircraft. How do the blade type antennas normally differ from whip antennas?
shorter in length than the whip antennas
The heart of the VHF COM system is a:
Transceiver
(in order to communicate you need to be able to talk and listen. TRANSmit and reCEIVE. Transceiver.)
What is a transceiver?
a radio transmitter and receiver enclosed in one common housing
What does the VHF COM control head contain?
Channeling switches, displays, volume control, and squelch control.
(Think of a cell phone.
Channeling switches - keyboard
Displays - screen
Volume Control - volume buttons
Squelch Control - Ringtone on/off up/down)
Many times the microphone input and audio output are connected to:
the Audio System (or Audio Control Panel) in the aircraft.
On small aircraft the transceiver and control head are:
combined into a single unit
Most large aircraft, use an integrated flight management system (FMS) which includes what functions?
navigation and communication functions
The FMS system has modules also known as:
Line Replacement Units (LRUs) that are connected to a common power supply and data buses
(The FMS is a software.
The LRU is the computer box.)
Aircraft with an FMS do not have control heads but are controlled through a:
Multifunctional Control Display Unit (MCDU for AirBus, CDU for Boeing).
(If FMS is software
And LRU is a computer
The MCDU/CDU is just the screen and keyboard)
In many smaller aircraft the VHF communication system is combined with:
the navigation system and mounted in the instrument panel
(Navigation and communications go hand in hand)
Typical testing of VHF communications includes checking:
SWR (Standing Wave Ratio), antenna and transceiver signal/power strength
The IF 4000 verifies the operation and installation of:
ILS, VOR, and Marker Beacon receivers, and VHF/UHF, AM/FM, and HF AM/SSB transceivers
The SelCal Decoder is designed to:
relieve the pilot and copilot from continuously monitoring the aircraft radio receivers.
The decoder is, in effect, an automatic monitor that listens for:
a particular combination of tones that are assigned to the individual aircraft.
When a coded transmission is received from a ground station, the signal is decoded by the Selcal unit which then does what?
alerts the flight crew to an incoming
message.
(SelCal = Steve from Blue’s Clue’s
“Here’s the mail, it never fails
It makes me want to wag my tail
When it comes I want to wail
MAIL!”)
The SELCAL system automatically activates what?
the correct radio for the flight crew
When the proper tones are received from the ground station, the decoder does what?
Operates an external alarm circuit to produce a chime, light, buzz, or combinations of thes signals.
(Decoder = Mailman bringing the mail to Steve)
How many channels are available in VHF COM?
2280 channels
