A digital phone call (DSL, ISDN) is transmitted as an audio frequency. If you listen in to the transmission signal, though, all that you can hear is an incomprehensible twittering noise. This is because the signal is digitized and coded in binary form. At the beginning you will hear the dialing tone, a sequence of different pitches containing the call number in coded form. The subsequent twittering noise is then the digital call signal.
Information and ideas:
Students can carry out their own experiments with a classic analog modem with a monitor speaker which is a very good way to study the transmission of digital data in the audio frequency range. If you carry out the connection test with T-Online, for example, you can see what is happening and being transmitted at that moment in a text log displayed on the screen parallel to the audible sound.
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Learning resource type:
Sample audio clip
Information and Communication Technology (ICT); Physics; Technology
Grade 5 to 6; Grade 7 to 9; Grade 10 to 13
Middle/high school; Vocational training
Coding; Communication; Computer technology; Data processing; Digital technology; Signal (electricity); Speech; Coding; Communication (technical); Data processing (electronic); Data technology; Digitization; Signal transmission; Signaling technology; Speech
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