Transceivers

Aircraft are generally equipped with at least one communications radio set operating in the Very High Frequency (VHF) range.

These radio sets are both a transmitter and a receiver and are called Transceivers.

The items associated with the main transceiver in the cockpit are:

• Microphone used to transmit messages;
• Speaker/headset for listening to received messages;
• Master switch(electrical) to give power supply to the radio;        

Adjustment of the controls of commonly used aeronautical transceivers.

Squelch Control

May be fixed or adjustable with a knob or a sequence of button presses.

Typically the operator will adjust the control until the unwanted noise is heard, and then adjusts in the opposite direction until the noise is squelched.

At this point, the weaker and wanted signal will be heard by the operator.

Caution:  If the squelch control is turned down too low, the wanted signal could be muted.

Microphone Techniques (PTT - Push To Talk)

• The microphone should be positioned directly in front of, and close to your mouth.
• To transmit your message, hold down the microphone transmit button fully on the control, pause and then speak. 
• Finish the message, pause, then release the transmit button. 
• Do not depress the transmit switch until ready to speak. 
• Speak at a normal and slightly slower conversation level. 
• It is not possible to receive messages while you are transmitting.
• While you are transmitting on a given frequency, no one else can transmit on that frequency.
• Make sure the button is released when finished transmitting.
• Think about what to say before you press the transmit button.
• Pausing between pressing the microphone button and speaking gives the radio time to stabilise the transmission.