# Why the value of modulation index is less than 1?

So when m is greater than one, over-modulation occurs and the modulating signal being of greater amplitude,part of its information is lost in the process of modulation which is undesirable. Hence its modulation index is kept below 1.
A.

### What is frequency modulation index?

Here is a simple FM signal: Here, the carrier is at 30 Hz, and the modulating frequency is 5 Hz. The modulation index is about 3, making the peak frequency deviation about 15 Hz. That means the frequency will vary somewhere between 15 and 45 Hz.
• #### What is modulation index for FM?

The modulation index (or modulation depth) of a modulation scheme describes by how much the modulated variable of the carrier signal varies around its unmodulated level. It is defined differently in each modulation scheme. Amplitude modulation index. Frequency modulation index.
• #### Why the modulation index is kept low?

If the modulation index is greater than , that means the amplitude of the modulating wave is higher than that of the carrier wave. This causes over- modulation of the carrier wave which results in distortion. Thus, a low modulation index is always maintained.
• #### What is frequency deviation of FM?

Frequency deviation ( ) is used in FM radio to describe the maximum difference between an FM modulated frequency and the nominal carrier frequency. The term is sometimes mistakenly used as synonymous with frequency drift, which is an unintended offset of an oscillator from its nominal frequency.
B.

### What is the value of amplitude modulation index?

A is the carrier amplitude. M is the modulation amplitude and is the peak change in the RF amplitude from its unmodulated value. From this it can be seen that for an AM modulation index of 0.5, the modulation causes the signal to increase by a factor of 0.5 and decrease to 0.5 of its original level.
• #### What is the use of carrier signal?

A carrier signal is a transmitted electromagnetic pulse or wave at a steady base frequency of alternation on which information can be imposed by increasing signal strength, varying the base frequency, varying the wave phase, or other means. This variation is called modulation.
• #### What is the image frequency?

In heterodyne receivers, an image frequency is an undesired input frequency equal to the station frequency plus (or minus) twice the intermediate frequency. The image frequency results in two stations being received at the same time, thus producing interference.
• #### Can modulation index be greater than 1?

So when m is greater than one, over-modulation occurs and the modulating signal being of greater amplitude,part of its information is lost in the process of modulation which is undesirable. Hence its modulation index is kept below 1.
C.

### What are the different types of modulation?

There are 3 basic types of modulation: Amplitude modulation, Frequency modulation, and Phase modulation. a type of modulation where the amplitude of the carrier signal is modulated (changed) in proportion to the message signal while the frequency and phase are kept constant.
• #### What is meant by Delta Modulation?

A delta modulation (DM or Δ-modulation) is an analog-to-digital and digital-to-analog signal conversion technique used for transmission of voice information where quality is not of primary importance. The analog signal is approximated with a series of segments.
• #### What is the analog modulation?

Analog modulation refers to the process of transferring an analog baseband (low frequency) signal, like an audio or TV signal over a higher frequency signal such as a radio frequency band. There are two ways to modulate an RF carrier: 1.
• #### What is depth of modulation?

The modulation index (or modulation depth) of a modulation scheme describes by how much the modulated variable of the carrier signal varies around its unmodulated level. It is defined differently in each modulation scheme. See: Amplitude modulation index. Frequency modulation index.

Updated: 2nd October 2019