Communication means exchange of views. In order to establish Communication we need a transmitter, a receiver and a media. A low frequency signal may be audio, video or other type is modulated inside the transmitter and through a media directed towards the receiver where signal is recovered after detection. The purpose of communication is to convey information from one place to other.
Typical Communication Systems. Communication plays a vital role in flying station. With the help of signal and radio equipment. ‘Communication links’ are established between ground to air, air to ground, ground to ground, for passing various information between one place to another.
Air to Ground & Ground to Air Communication. The basic purpose of this network is to aid the flying aircraft and to supply various information demanded by the aircraft, e.g., homing/bearing, weather conditions, landing aids or other mission control information. It is carried out with the help of signal equipments fitted both in aircraft and at ground. In terms of frequency, these equipments are divided into two categories, viz., HF equipment and VHF equipment.
Generally a VHF trans-receiver is equipped in aircraft, which is of comparatively small size to reduce the weight and occupies less space. These are called airborne equipments and established for RT communication only.
In case if the above fails, then pilot can be aided by HF trans-receiver which are not popularly used now a days.
Besides the above, at ground, numbers of facilities are extended to the aircraft and ground stations.
HF Range. Inter tower RT (Open/Confidential) and stand by facilities to HF RT.
(a) Met broadcast RT reception channel.
(b) NOTAM reception channel.
VHF Range.VHF transmitter and receiver to establish the communication between ground to air. The number of channel will vary from station to station as per demand.
(a) Medium frequency beacon (for Airborne Radio Compass).
(a) V/UHF direction finder and Standby set of DF.
(a) Instrument Landing System.
(iii) Glide Path
(b) Eureka/Rebecca (Radar).
(c) Ground control approach (GCA) it consists of procession approach radar and search radar equipment.
In addition to the above, tape recorders are placed in air traffic control (ATC) to record the conversation of pilot with ground station. Such recordings are very helpful in aircraft accident/incident investigations. The same job is carried out in aircraft by equipments like
(a) Cockpit voice recorder.
(b) Digital Flight Data Recorder (Black box).
Black Box is totally full proof from all external stimuli. Likewise detection can also be in terms of amplitude, frequency or phase. Amplitude modulation has advantage of simplicity of equipment where as FM/PM has advantage of less noise, better clarity but range is comparatively low.
Fibre Optical Communication System. It is a long haul in communication which use light as a media for carrying various intelligences. e.g. Audio, Video, analog or digital Signal. This concept was firstly given by American scientist Charles Kao and George Hookem. It was practically shaped by M/S Corning Glass Works by making a optical Transmitter (Txr), optical Receiver (Rxr) and a propagating Media. Later it was further improved by Bell Labs of USA. Today this system has emerged out as leader of communication. Silica in its pure form possesses optical qualities; that’s why it is used for this purpose.