Courses
Courses for Kids
Free study material
Offline Centres
More
Store

# Difference between AM, FM and PM

Last updated date: 15th Jul 2024
Total views: 60.9k
Views today: 1.60k

## What is AM, FM, and PM?

In FM, a radio wave known as the "carrier" or "carrier wave" is modulated in frequency by the signal that is to be transmitted. However, the amplitude and the phase constant remain constant in the case of frequency modulation. While amplitude modulation or AM is a technique that we use in electronic communication, most commonly for transmitting information through a radio carrier wave.

Additionally, there is a term that is one of the two principal forms of angle modulation alongside frequency modulation, and it is called phase modulation. PM is a modulation pattern that we use for conditioning communication signals for transmission.

This page will help you distinguish between amplitude modulation and frequency modulation. Also, you will get to learn the difference between FM, AM, and PM modulation in tabular form.

### How does FM Work?

Frequency modulation works by continuously changing the strength of the transmitted signal in relation to the information being sent.

FM radio uses frequency modulation. However, to understand frequency modulation, assume a signal with a low frequency and amplitude. As the signal passes, its frequency remains unchanged or unmodulated. We find that a signal carries very little information.

So, when you introduce information to this signal, there's a variation to the frequency that varies directly with the information. Also, when the frequency is modulated between low and high, the carrier frequency transmits music or voice. Therefore, we find that the frequency changes as a result, but the amplitude remains constant the entire time.

For example, the changes in the strength of the signal may be utilized to specify the sounds to be reproduced by the speaker, or the light intensity of television pixels.

### How does an AM Work?

While receiving input signals, an AM receiver discovers amplitude variations in the radio waves at a specific frequency. It amplifies changes in the signal voltage to operate a loudspeaker or earphone.

Working principle of an AM receiver in reality:

In this, a radio receiver is present in the opposite of a radio transmitter that uses an antenna to capture radio waves. Further, it processes those waves to elicit only those waves that are vibrating at the needed frequency and filters the audio signals that were added to those waves, following, amplifying the audio signals, and finally plays them on a speaker.

### How does PM Work?

Phase modulation encodes a message or an input signal as variations in the instantaneous phase of a carrier wave.

In phase modulation, the working principle is that the instantaneous amplitude of the baseband signal modifies the phase of the carrier signal thereby keeping the constant amplitude and frequency. The phase of a carrier signal is modulated by phase modulation to follow the altering signal level or amplitude of the message signal.

Furthermore, the peak amplitude and the frequency of the carrier signal are also kept constant. However, as the amplitude of the message signal alters, the phase of the carrier also changes.

### Difference between AM and FM

Below is the table of AM versus FM:

### Difference between AM, FM, and PM

 S.No. Parameters FM AM PM 1. Definition Frequency modulation is a technique of modulation, in which the frequency of the carrier varies in accordance with the amplitude of the modulating signal. The amplitude and phase are constant. Amplitude modulation is a technique of modulation in which the amplitude of the carrier wave varies in accordance with the amplitude of the modulating signal. The frequency and phase are constant. Phase modulation is a technique of modulation in which the phase of the carrier wave varies in accordance with the amplitude of the modulating signal. The amplitude and frequency are constant. 2. Noise Noise immunity of FM is superior to AM and PM. AM receivers are very susceptible to noise. Noise immunity is better than AM but not FM. 3. Function The frequency of the carrier wave deviates as per the voltage of the modulating signal input. The amplitude of a carrier wave in AN diverges as per amplitude or voltage of modulating signal input. A phase of the carrier wave varies as per the voltage of modulating signal input. 4. Constant parameter The amplitude of the carrier wave is kept changeless. The frequency of the carrier wave is kept invariable. The amplitude of the carrier wave is kept changeless. 5. Types Digital FM types: FSK, GFSK, offset PSK, etc. AM types: DSB-SC, SSB, VSB, etc. Digital PM types: QPSK, BPSK, QAM (the combination of amplitude and phase, modulation). 6. Waveforms (Image will be Uploaded soon) (Image will be Uploaded soon) (Image will be Uploaded soon)

For a radio signal to carry audio or other information for broadcasting or for two-way radio communication, signals must be modulated or changed in some way. Though we have several ways in which a radio signal may be modulated, one of the easiest is to change its amplitude in line with variations of the sound. Here, we discussed three types of modulation, viz: FM, AM, and PM, which will help you understand the basics of the modulation along with the difference between each.

## FAQs on Difference between AM, FM and PM

1. What is the modulation?

Modulation is a technique in electronics that is used for impressing a piece of information such as voice, music, picture, or data on a radio-frequency carrier wave by changing one or more features of the wave in accordance with the intelligence signal. The most commonly altered features include amplitude, frequency, phase, pulse sequence, and pulse duration.