Combining the low frequency signal with very high frequency radio wave is called
Modulation: Combining Signals for Transmission
The process of combining a low frequency signal with a very high frequency radio wave is known as modulation. This fundamental concept is crucial in various communication systems, including radio, television, and mobile phones. Understanding modulation helps explain how information travels wirelessly over long distances.
What is Modulation?
Modulation is the technique where a property (like amplitude, frequency, or phase) of a high-frequency carrier wave is varied in accordance with the instantaneous amplitude of a low-frequency message signal. Here's a breakdown of the key components involved in modulation:
- Low Frequency Signal (Message Signal): This is the information we want to transmit, such as audio (voice, music), video, or data. Its frequency is typically low, making it unsuitable for direct long-distance transmission.
- Very High Frequency Radio Wave (Carrier Wave): This is a high-frequency, stable waveform that "carries" the message signal. It's chosen for its ability to travel efficiently through the air and allow for smaller antennas.
By varying the carrier wave's properties according to the message signal, the low-frequency information is essentially "encoded" onto the high-frequency carrier. This modulated signal can then be transmitted through the air.
Why is Modulation Necessary?
Modulation serves several critical purposes in wireless communication:
- Efficient Radiation: Low-frequency signals would require impractically large antennas for efficient radiation. High-frequency carrier waves, produced through modulation, allow for reasonably sized antennas.
- Avoiding Signal Mixing: Without modulation, if multiple signals were transmitted simultaneously, they would interfere and mix up, making it impossible to differentiate them. By modulating signals onto different carrier frequencies, multiple transmissions can occur simultaneously without interference (e.g., different radio stations on different frequencies).
- Increased Transmission Range: High-frequency radio waves, used in modulation, can travel much longer distances efficiently compared to low-frequency signals.
Analyzing the Options
Let's examine why the other options are not the correct answer for combining a low frequency signal with a very high frequency radio wave:
| Option | Explanation |
|---|---|
| Demodulation | This is the exact opposite of modulation. Demodulation is the process of extracting the original low-frequency message signal from the high-frequency modulated carrier wave at the receiver end. |
| Coding | Coding refers to the process of converting information into a specific format (e.g., binary code, error-correcting codes) for efficient storage or transmission. While often used in conjunction with modulation (e.g., digital modulation), it's not the act of combining the low-frequency signal with the high-frequency radio wave itself. |
| Superimposition | Superimposition is a general principle in wave physics stating that when two or more waves overlap, the resultant displacement at any point is the vector sum of the displacements of the individual waves. While modulation involves combining signals, superimposition is a broader concept and not the specific engineering term for preparing a signal for radio transmission. Modulation is the precise and correct term in this context. |
Conclusion
Based on the definitions and purposes of these communication processes, the act of combining a low frequency signal with a very high frequency radio wave for transmission is accurately described as modulation.
Important Questions from Modulation
During the heterodyne process in the receiver, the modulation of the signal __________
Which of the following modulations is used in India for radio transmission?
- Which of the following is a result of over-modulation?
Which of the following statements are correct?
A. DSB‐SC modulation is well suited for point to point communication involving one transmitter and one receiver.
B. VSB modulation is a linear modulation scheme.
C. SSB is a non‐linear modulation scheme.
D. FM is a linear modulation scheme.
Choose the correct answer from the options given below:
The process of superimposing message signal with the carrier wave is known as :
