You can work on amplitude modulation (AM), frequency modulation (FM), or phase modulation (PM) based analog communication projects in analog communication projects. You've probably heard that each town and city has its own radio station. It's commonly referred to as an 'FM Radio Station.' Frequency modulation (FM) is the technology utilized to operate such radio stations. It has a frequency range of 90 to 108 MHz.
A high-frequency carrier is required to transmit any baseband signal. It's nearly difficult without a carrier. We've already talked about why modulation is so important. You are welcome to look through it. We modulate our original speech signal with a high-frequency carrier wave and change the frequency of the modulated carrier signal by the amplitude or voltage of the voice signal to transmit it.
For your information, a vocal transmission, for example, is first translated into an electric signal. It is now known that distinct voltage levels exist for different signals. Now, the carrier wave's frequency is varied by the voltage or current of voice signals, allowing us to transfer data through free space or air.
Now, for a better understanding, we'll go over basic mathematical concepts.
Vc = A*Sin(ฮธ) = A* Sin (wt + ฮฆ)
The above equation is a modulated signal notation, which shows that all signals have some common properties such as amplitude, frequency, and phase. Our portfolio in this article is frequency modulation or FM. So, in this case, we're primarily interested in the modulated signal's frequency component.
As the amplitude or voltage of the speech signal varies, the carrier signal's frequency swings in a certain range. In that instance, we see a certain level of frequency deviation.
For instance, we can represent it numerically as follows:
Fi = Fc + ฮFc
where Fi is the instantaneous frequency that the FM receiver receives. Fc is the carrier signal's frequency, and ฮFc is the frequency deviation which is basically responsible for carrying information.
Assume, for example, that you have a wideband FM signal.
The standard bandwidth of a wideband FM is 200 kHz. A frequency deviation of +/-75 kHz is used on both sides, as well as an extra guard band of 25 kHz, to protect the signal from interference from other radio stations.
Now the entire band will have the same appearance.
25 KHz + 75 KHz + 75 KHz + 25 KHz (guard band + frequency deviation (due to -75 KHz deviation + frequency deviation (due to +75 KHz deviation + guard band)
As previously stated, the bandwidth of the above FM channels is 200 KHz. Wideband FM has been demonstrated in the example above.
When the ratio of the highest to lowest operating frequency (positive frequency) is substantially more than one. Then it's known as a wideband signal. On the other hand, if the radio is close to 1, it is referred to as a narrowband signal.
For realistic FM broadcasting First, the microphone converts the original voice signal to an electrical signal, which is then passed via a pre-amplifier to amplify the millivolt signal into a stronger signal, which helps to enhance the signal-to-noise ratio. The next stage is to use an oscillator to generate a high-frequency carrier wave, which is then modulated by the baseband message or speech signal. Final amplifiers compensate for signal attenuation after it has passed through the modulation step. Finally, the signal is sent from the transmitter to free space or air. Read More...
MATLAB code for FM (Frequency Modulation) Signal
Output
Also read about
[1] Digital Communication Mini Projects
[2] More Wireless Communication Projects/Thesis ideas for Final Year Students [click here]
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#analog and digital communication projects
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