Physics 1F

Physics 1F

1. Analogue and Digital signals

   • Analogue signals have a continuously variable value
   • Digital signals are either on (1) or off (0)
     • The advantages of using digital signals include: that it is easier to remove noise and you can use multiplexing

2. Infrared

   • Everyday uses of infrared radiation include: remote controls and short distance data links
   • Infrared sensors detect body heat

3. The advantages of using optical fibres include: multiplexing and lack of interference in the final signal

   • Multiplexing is when you send more than one signal on a carrier wave

4. Key Processes

   • Digital signals carry more information per second than analogue signals and they maintain their quality better over long distances. This is why we are switching to digital TV and radio
   • Information such as computer data and telephone calls can be converted into infrared signals and transmitted by optical fibres. Optical fibres are able to carry more information than an ordinary cable of the same thickness. In addition the signals they carry do not weaken so much over long distances. Television remote controls use infrared light to transmit coded signals to the television set in order to, for example, change channels or adjust the volume
   • Noise also adds extra random information to digital signals. However, this noise is usually lower in amplitude than the 'on' states of the digital signal. As a result, the electronics in the amplifiers can ignore the noise and it does not get passed along. This means that the quality of the signal is maintained