A wireless communication system has a transmitter at one end and a receiver at the other. Also it is possible to have both transmitter and receiver built into one device called transceiver. However the following diagram shows a one way communication system where the transmitter and receiver is shown separately.

process of transmitting and receiving

The explanation of the each block function is as follows. An information signal is passed into the modulator at the transmitter. The information signal can be analog or digital. Analog signal examples are audio or speech signals. The process of modulation embeds the information into another signal suitable for transmitting over the air. The modulated signal is then bandpass filtered to limit the information carrying signal to a certain bandwidth and avoid interferences with other channel among others. The modulated and bandpass filtered is then mixed with some high frequency carrier signal by the mixer. The output is then bandpass filtered again and finally amplified before sending to the antenna.

At the receiver the receving antenna detects the signal. This is bandpass filtered and then passed through a LNA(Low Noise Amplifier). After that it is mixed with locally generated frequency to down-convert the high frequency to some intermediate frequency(IF). The IF frequency signal is again bandpass filtered and amplified to a suitable for demodulation. In the demodulator, the information signal is extracted from the information bearing signal.


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