Digital satellite receivers sets the frequency of the programme that we wish to view. After amplification, the signal is processed and if it is security encrypted it will be decoded, so that the original sound and information is recovered. The audio/video signal can then be fed to a television using a scart cable or modulated onto an RF channel which can be viewed through the aerial input of the television.
Digital satellite receivers use a microprocessor to carry out the majority of these functions. The software which manages the microprocessor can be updated through satellite transmissions, which is why they are best left connected to the mains power.
As mentioned earlier some satellite transmissions are encrypted, sometimes to particular countries eg Viaccess, Irdeto, Videoguard etc. The reason for this is copyright limits the reception of certain channels to particular countries and other channels cost a premium to make so have to be paid for, the encryption safeguards this. The conditional access module (CAM) is the part of a digital satellite receiver which a viewing card is placed in order to unlock the encrypted channels.
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