Navigation and Seamanship

 

6.5.2. Working principle

                                                

When the magneticlines of force of a radio wave out across a receiving antenna, a voltage causesa current to flow between the antenna and ground. The antenna of the radioreceiver will separate the desired signal with particular frequency from the available signals. The process of selecting the frequency is called tuning.The signal received after tuning is the modulated radio frequency carrier of a particular transmitter is very weak and requires amplification. Then the amplified modulated signal is fed into a demodulator for recovery of audio frequency from the carrier waves. Conversion of the audio frequency signal into sound waves is done by loudspeakers.

The following are the six steps in receiving radio signals,

1. Radio waves of many frequencies and from many sources induce electric current in an antenna

2. A tuner selects the modulated carrier signal of the desired frequency.

3. The signal is modified.

4. The audio frequency signal is separated from the radio frequency carrier.

5. The audio frequency signal is amplified.

6. The electrical audio frequency signal is converted into sound waves.