求翻译：A basic radio communication system consists of a microphone or key,a transmitter and transmitting aerial, a receiver and receiving aerial ,and a loudspeaker or headphones. The microphone or Morse key produces an electrical signal . The radio transmitter generates radio-frequency waves which vary in accordance with the electrical signal. The transmitting aerial radiates these waves into space and receiving aerial receives them. The radio receiver amplifies the signal and reproduces the original electrical signal. The loudspeaker or headphones convert this signal into sound, consequently the original sound is reproduced. In a radio communication system the information to be transmitted must first be converted into an electrical signal. In radio-telegraphy this is done using a Morse key or microphone. These radio waves are generated by the transmitter at a definite frequency. After that, they are conveyed to the transmitting aeriai for radiation. The receiving aerial picks up the radio signal in addition to a mass of other signals as well. The radio signal is then dealt with by the radio receiver. The receiver must do a number of things. After selecting the desired signal, it must amplify it. After that, it must reproduce the original electrical signal, which is then sent to headphones or a loudspeaker. These reproduce the original sound and, therefore ,complete the system.是什么意思？

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