Frequency Modulation: Historical Background and Basics

Frequency modulation (FM) is the widely utilized form of radio communications applications. FM broadcasts on the VHF bands continue to provide an extremely high audio quality, and FM is used for a wide array of forms of two way radio communications. It’s especially helpful for mobile radio communications, and is usually used in taxis and a lot of other vehicles as well.

In line of its widespread utilization as a FM-Band band pass filter or for other forms of communication systems, FM is also an essential form of modulation. Despite its numerous forms of digital transmission being utilized these days, FM frequencies continue to provide clearer signals for radio communication.

History of Frequency Modulation

FM has been utilized by many for a lot of years. However, its benefits were not immediately realized. In the early wireless days, it was considered that a narrower bandwidth was required to reduce noise and interferences. As FM failed to perform effectively under these conditions, AM then predominated and FM was never to be used. However, American engineer Edwin Armstrong looked at the use of wideband FM in broadcast communication and introduced the thought against the thinking trend of the time.

Ever since then, FM has grown enormously. Nowadays, wideband FM is still acknowledged as a form of very high quality transmission medium for high quality broadcasting. Plus, it’s also used for communication where it’s resilient to different signal strengths.

FM Concepts: The Need for Modulation

For a successful transmission and information reception, modulation is considered to be an essential process. Both audio and video signals can’t be sent directly from a broadcast station for a thousand miles, as these signals are both low on frequency and power. The signal strength diminishes as it propagates due to varying atmospheric effects. Other reasons for modulation include:

Mutual interference takes place if everyone starts sending low frequency signals
For a proper reception of signals, the size of the antenna should be of the wave length order of the signal ready to be received. Therefore, the lower the signal frequency the greater its wavelength will be and much larger antennas will be required and vice versa.

FM Frequency Features

The most noteworthy feature of frequency modulation is its resilience to varying signal levels. The modulation is carried only as variations in frequency. That is, any signal level variations won’t affect the audio output, provided that the signal doesn’t fall in a level that the receiver can’t cope up with.
FM waves possess a resilience property to noises and interferences. It’s for this reason that FM is utilized for high quality broadcast transmissions.

FM Transmission Applications

FM, as mentioned above, is usually utilized in VHF radio frequencies for high-fidelity broadcasts for both music and speech. Regular TV sound is also broadcasted through FM transmissions. The FM-Band band pass filter utilized in broadcast is typically called a wide-FM, or W-FM. In two-way radio, Narrowband-FM (N-FM) is used to conserve bandwidth. Adding up to the fray, it’s used to send signals into space.