![]() In this case the carrier is made to move up and down by 3 kHz.īroadcast stations in the VHF portion of the frequency spectrum between 88.5 and 108 MHz use large values of deviation, typically ☗5 kHz. As an example the signal may have a deviation of plus and minus 3 kHz, i.e. It is known as the deviation and is normally quoted as the number of kilohertz deviation. The amount by which the signal moves up and down is important. When the audio signal is modulated onto the radio frequency carrier, the new radio frequency signal moves up and down in frequency. ![]() To generate a frequency modulated signal, the frequency of the radio carrier is changed in line with the amplitude of the incoming audio signal. A low cost FM broadcast radio What is frequency modulation, FM? Whether for fixed or mobile radio communication systems, or for use in portable applications, FM is widely used at VHF and above. In addition to its widespread use for high quality audio broadcasts, FM is also used for a variety of two way radio communication systems. These transmissions could offer high fidelity audio, and for this reason, frequency modulation is far more popular than the older transmissions on the long, medium and short wave bands. It is able to provide near interference free reception, and it was for this reason that it was adopted for the VHF sound broadcasts. Frequency modulation is widely used on frequencies above 30 MHz, and it is particularly well known for its use for VHF FM broadcasting.Īlthough it may not be quite as straightforward as amplitude modulation, nevertheless frequency modulation, FM, offers some distinct advantages. It is also possible to change the frequency of a signal to give frequency modulation or FM. ![]() ![]() ![]() While changing the amplitude of a radio signal is the most obvious method to modulate it, it is by no means the only way. Modulation formats: Modulation types & techniques Amplitude modulation Phase modulation Quadrature amplitude modulation What is Frequency Modulation, FM Frequency modulation, FM, is used in many applications from broadcasting to communications and offers several advantages over other modes.įrequency modulation, FM Modulation index & deviation ratio FM sidebands, bandwidth FM demodulation FM slope detector FM ratio detector Foster Seeley detector PLL FM demodulator Quadrature demodulator MSK GMSK ![]()
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