The process of receiving more than one channel on the same frequency on satellites involves several steps. Firstly, carrier frequency, which is the frequency of a carrier wave used for signal transmission, is modulated. Modulation can be done in various ways, such as frequency modulation (FM), amplitude modulation (AM), or phase modulation (PM). In satellite TV transmission, frequency modulation is commonly used.
Digital frequency modulation is predominant in satellite TV transmissions, where the carrier's frequency is varied based on binary data. Frequency-division multiplexing (FDM) is employed to combine multiple signals onto a single channel by assigning each signal a different frequency.
At the receiving end, demodulation is carried out to recover the transmitted data. Signals are received through a satellite dish and a low-noise block (LNB) down converter. The desired television program is then decoded for viewing.
FDM involves a demultiplexing process, where signals are modulated and transmitted over separate bands, then combined and transmitted over the channel. At the receiving end, the combined signal is demultiplexed to extract individual signals. Double-sideband suppressed-carrier transmission (DSB-SC) is used, where frequencies produced by amplitude modulation (AM) are symmetrically spaced above and below the carrier frequency, ideally suppressed, to reduce complexity in demodulation.
