A transmitter is an electronic assembly that conditions signals so that they can be transmitted via transmission medium. The term transmitter is most often used in connection with radio technology equipment in which the signals are processed for radio transmission and adapted to the air interface. However, it can also refer to an optical transmitter that generates the light signals for the FOC transmission link.
A radio transmitter consists of an oscillator, modulator, several RF amplifiers and an RF power amplifier that provides frequency, impedance and level matching to the antenna. The oscillator generates the transmit or carrier frequency. This frequency is modulated in the modulator with the signal to be transmitted. Depending on the radio network, a wide variety of modulation methods are used: Amplitude, frequency or phase modulation, or a combination of several methods.
The modulated carrier signal is then processed in the RF amplifiers and adapted to the radio characteristics of the antenna in the RF power amplifier. For this purpose, the carrier frequency is amplified in terms of power and the output impedanceof the RF power amplifier is matched to the antenna impedance. The output signal of the transmitter is transmitted to the antenna, from where it is released as an electromagnetic radio wave.
The transmitting power is specified as an effective value or as peak RF power.