In an analogue microwave link, the baseband video and audio signal from the camera and the microphone is connected to the input of the modulator. This takes the basic message signal and modulates it, using the FM process, turning it into an RF signal called the intermediate frequency (IF) signal typically based on a 70 MHz carrier. The output of the modulator is fed to an upconverter, which shifts the frequency of the IF signal from the relatively low 70 MHz frequency up to the super high frequency (SHF) of the microwave transmitter – typically in the 2.5, 5 or 7 GHz frequency bands. This is then amplified, fed to the antenna and transmitted as a microwave signal. The power of the transmit amplifier is typically between 5 and 15 Watt (W), where Watt is the measurement of power.