In the context of gigahertz-range microwave communications, neither AM (Amplitude Modulation) nor FM (Frequency Modulation) is typically used. The terms AM and FM are more commonly associated with radio broadcasting in the audio frequency range.
Microwave communications refer to the use of electromagnetic waves with frequencies typically ranging from hundreds of megahertz (MHz) to several gigahertz (GHz) for transmitting data, voice, and video signals over long distances. In microwave communications, the modulation schemes used are different from traditional AM or FM.
Two common modulation techniques used in microwave communications are:
Phase Shift Keying (PSK): In PSK modulation, the phase of the microwave signal is varied to represent digital data. Common PSK variants include Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), and higher-order PSK schemes.
Frequency Shift Keying (FSK): In FSK modulation, the frequency of the microwave signal is changed to represent digital data. Common FSK variants include Binary Frequency Shift Keying (BFSK) and Multiple Frequency Shift Keying (MFSK).
These modulation techniques allow for efficient and reliable transmission of digital information over microwave communication links. The choice of modulation scheme depends on factors such as data rate requirements, available bandwidth, and the level of signal robustness needed to overcome various communication challenges.
So, in summary, in gigahertz-range microwave communications, neither AM nor FM modulation is used. Instead, digital modulation techniques like PSK and FSK are employed to transmit data, voice, and video signals.