# Amplitude modulation (AM)

Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the amplitude of the carrier wave in proportion to the information being sent. For example, if a carrier wave has an amplitude of 1 volt and is modulated so that its amplitude becomes 1.5 volts when transmitting a signal, then the modulation is said to be 50% amplitude modulation.

The information is typically encoded in the amplitude of a sinusoidal carrier wave. In an AM signal, the amplitude of the carrier wave is varied in accordance with the amplitude of the message signal. AM is the oldest form of modulation and is still in use today, particularly for medium wave (MW) and long wave (LW) transmissions.

### What is AM and FM and PM?

Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the amplitude of the carrier wave in proportion to the information being sent. For example, if a carrier wave has a amplitude of 1V and the information being sent is a sinusoidal signal with an amplitude of 0.5V, the resulting signal will have an amplitude that varies between 0.5V and 1.5V.

Frequency modulation (FM) is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. FM works by varying the frequency of the carrier wave in proportion to the information being sent. For example, if a carrier wave has a frequency of 100MHz and the information being sent is a sinusoidal signal with a frequency of 1kHz, the resulting signal will have a frequency that varies between 99.999MHz and 100.001MHz.

Phase modulation (PM) is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. PM works by varying the phase of the carrier wave in proportion to the information being sent. For example, if a carrier wave has a phase of 0 degrees and the information being sent is a sinusoidal signal with a phase of 180 degrees, the resulting signal will have a phase that varies between 180 degrees and 360 degrees.

### What is the difference between FM and AM modulation?

The main difference between FM and AM modulation is that in FM, the frequency of the carrier signal is varied in accordance with the amplitude of the modulating signal, while in AM, the amplitude of the carrier signal is varied in accordance with the amplitude of the modulating signal.

Other differences between FM and AM modulation include the following:

- FM signals are less susceptible to interference than AM signals.
- FM signals have a higher bandwidth than AM signals.
- FM signals can be transmitted over longer distances than AM signals.

##### What is amplitude modulation formula?

Amplitude modulation (AM) is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the amplitude, or strength, of the carrier wave in proportion to the information signal being sent. The information signal is typically a voice or music signal. The amplitude-modulated signal is then broadcast via antenna.

The strength of the amplitude-modulated signal is typically measured in terms of the modulation index, which is the ratio of the amplitude of the modulating signal to the amplitude of the carrier wave. The modulation index is a measure of the depth of modulation and is usually expressed as a percentage.

The AM formula is:

AM = A_c * (1 + m * cos(2 * pi * f_m * t))

where:

A_c is the amplitude of the carrier wave
m is the modulation index
f_m is the frequency of the modulating signal
t is time

#### What are the types of AM modulation?

There are two main types of AM modulation:

1. Double-sideband modulation (DSB)
2. Single-sideband modulation (SSB)

DSB is the most common type of AM modulation, and is used for most AM radio transmissions. In DSB, the carrier wave is amplitude modulated by the signal, resulting in two sidebands (upper and lower) being generated.

SSB is less common, but has some advantages over DSB. In SSB, only one sideband is transmitted, resulting in a more efficient use of the available bandwidth.