-: RF Remote Controls :-
In RF remotes radio frequency signals are used as an interface between transmitter and receiver. As we know radio frequency ranges from 10 KHz (VLF) to 10GHz (SHF) so it acquires very wide band. In RF remotes signal is modulated over RF carrier. Depending upon the carrier frequency used (also the modulation scheme used) RF remotes can be further classified into subcategories like AM (Amplitude Modulation), FM (Frequency Modulation), ASK (Amplitude shift keying), FSK (Frequency Shift Keying) etc.
Carrier frequency range of AM transmitters varies from 1 MHz to 10 MHz and they have very high range in terms of hundreds of kilometers (if it's very high power transmitter). Normal AM remotes have range of about 1-5 Km. They are very noisy that's why they are just used for voice communication.
Same way FM transmitter have carrier frequency range of 88-108MHz and an operating range of around 50-60 Km. Commercial FM remotes with low power transmitter has a range less then or around 1 Km. They are less noisy then AM remotes and so widely used in remote control applications.
For transmitting digital data over very high frequency ASK or FSK scheme is used. You will get totally noise free communication between transmitter and receiver. Frequency range starts from as high as 300 MHz and ranges up to 3 GHz. Operating range varies from 100-1000 Mt. They are very costly and only used for industrial remote control applications and wireless applications.
Some of the advantages of these remotes
Advantages:-
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Incredible high operating range in terms of hundreds of meters
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RF signals can penetrate through obstacles like wall, partition etc.
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No need of line of sight between transmitter and receiver
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No problem with directivity also means no need to point transmitter toward receiver
Also some of the draw backs are
Disadvantages:-
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They are bit more costlier because cost of components is increased
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Not so easy to implement as you have to take great care of noise
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Because of antennas it is bulkier
Although they are drawbacks but because of it's higher operating range and other advantages they are widely used in industries for wireless applications.
