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Communication in waves Cheat Sheet by

Btec physics unit 1 Btec science


Power and mode of transm­ission
Frequency band
How it is used and regulated
Satellite commun­ication
High power signals over very long distances; concen­trated by dish antennae
1 to 40GHz (micro­waves)
Satellite transp­onders recieve incoming upload signals, amplify them and retransmit them as a downward signal on a different frequency band
Mobile phones
High power networked system, range several km
800MHz to 2.6 GHz (UHF radio to microwave border­line)
5 or 10 MHz bands allocated to different operators. 2G, 3G and 4G cellular networks offering increasing speeds for data. Higher freque­ncies have greater data capacity but travel less distance through air and penetrate into buildings less well
Low power device to device links, range up to about 10m
2.4 to 2.4835 GHz - the industrial scient­ific, epically (ISM) unlicensed band - borderline between UHF radio and microwave freque­ncies
Early Bluetooth devices interfered with Wi-Fi devices because both would use the same channel for an extended period of time. Modern Bluetooth uses frequency - hopping - i.e. broadc­asting in short bursts on a number of different frequency channels across the band. This reduces the amount of data lost, and in most cases both Bluetooth and Wi-Fican maintain service
Medium power networked system, range ~ 10 to 100m
same as Bluetooth
same as bluetooth
Low power device to device links, range only a few meters
IR wavele­ngths 870nm or 930 to 950 nm (frequency about 320 THz)
Used for remote controls and for data transfer between computers, phones, etc. the longer wavelength band is better because it does not suffer from ‘sunlight blinding’. Atmosp­heric moisture blocks that range in sunlight


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