What is the function of a mixer in a radio transmitter?

A mixer in a radio transmitter plays a crucial role in the modulation process by combining signals from different sources, typically an incoming audio or data signal and a high-frequency carrier signal. This combination results in the creation of a modulated output signal, which is necessary for effective transmission.

The modulation process allows the information contained in the lower frequency audio or data signal to be superimposed onto the higher frequency carrier wave, making it suitable for transmission over long distances. In essence, the mixer facilitates the transition of baseband signals (lower frequency signals) into a form that can be efficiently radiated by antennas.

This function distinguishes it from other components that you might find in a radio transmitter. For instance, while amplifying signals is important, it is typically done in separate amplification stages after the modulation process. Similarly, decoding and filtering functions serve different purposes that do not involve the primary mixing role central to producing a modulated signal for transmission.