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In this section, we will look at the radio equipment used in aircrafts. There is no difference between that in airplanes or in helicopters.
This section will cover the following basics:
The transceiver is the heart of the system, and consists of 2 sub-systems: the transmitter and the receiver,
hence the name transceiver. The transceiver works in the VHF (Very High Frequency) radio spectrum range (General / Civil Aviation).
All communications use amplitude modulation (AM). To communicate with another party or facility, both parties must agree upon the
frequency to use, otherwise there isn’t an effective communication channel. These frequencies range from 118,000 to 136,975 MHz.
For an overview of common frequencies, see the Communications Frequencies’ Overview. The resolution of the frequencies used has
typically been 0.050 MHz, although nowadays you may also encounter 0.025Mhz. This means that the frequency selected is a multiple
of 0.050 or 0.025 MHz.
The only action you are required to take is to choose the right frequency. What is more, all digital radios enable you to store those
that are most commonly used (e.g. control, tower, departure, centre, unicom, etc.).
Of course, you need a microphone to talk in to. All hand held microphones have a Push-To-Talk button (PTT button). Note that your
transceiver will either be transmitting or receiving, but it will never do both at the same time (this is called Simplex communication,
as opposed to the Duplex mode, where you can simultaneously speak and listen). You must keep the distance between your lips and the
microphone to almost zero, which enables your voice to be broadcast at maximum amplitude despite the noise in the cockpit.
In order to hear what you are being told, you need to use earphones. There are many different kinds available. For example, you can utilise
an earset with just one earphone, meaning that you can listen to ATC and the environment around you or your passengers. You also can
use a pair of earphones (headset), which will reduce much of the noise in the cockpit. For the quietest experience, headsets with
electronic noise cancellation technology are available. You will probably want to experiment before determining your favourite, but,
these days, using a headset is common sense.
Headsets also come with boom microphones, which take away the need to return the microphone to its holder every time you have
finished using it.
Whenever you wear a headset, talking to your passengers is impractical. This is where the intercom comes into play, since it enables everybody
wearing a headset to talk to each other. This means that every passenger should wear one. This configuration is becoming more and more
common in the general aviation fleet. The intercom system also inter-connects with the transceiver, thereby allowing the pilot to talk to
both passengers and ATC.
Audiopanels come in handy when using two transceivers. With 2 transceivers, you have the ability to listen to two channels simultaneously,
for example, to ground control and the tower. The audiopanel enables you to: select different configurations, such as transmitting on
channel one or two (a channel now is one of the two transceivers) while listening to both; listen to the cabin speakers, the headset or both;
assign a channel to the cabin speaker or choose to always make the chosen channel audible on the cabin speakers, and so on. By using two
transceivers with an audiopanel, you also can keep each transceiver’s settings at the desired position, since you do not have to switch
frequency every time you use it.
As well as installed transceivers, it is also possible to obtain handheld models, which play an important role in circumstances where the
installed systems stop functioning (for example, due to a power failure, or a blank display). Modern digital handheld transceivers are a
remarkable piece of technology, with a great deal of functionality within a small unit. Handhelds are also useful for monitoring
communications on the ground, from which you can learn a great deal.
Uniden BC72XLT Bearcat Handheld Scanner (Black)
This fairly priced scanner is particularly well suited to listening to aviation communications. It features a 100 channel memory,
which is organized into 10 memory banks of 10 channels each. The Uniden BC72XLT is very light and small, and can easily be carried
with you. It is a very exciting piece of technology, which will bring you much closer to understanding how aviation communications work.