Table of Contents
- 1 How will you produce an AM signal?
- 2 What is the effect on received signal in AM if the modulating signal amplitude is more than the carrier amplitude?
- 3 What is the difference between AM and FM waves?
- 4 What happens to the AM waveform during the demodulation process?
- 5 What happens to the modulation index of an AM signal if the modulating signal voltage is higher than the carrier signal voltage?
- 6 What are the advantages of AM over FM signal?
- 7 What is effect of change in modulating signal frequency on modulation index?
- 8 How does an AM radio work?
- 9 How does AM signal travel over the Earth?
- 10 What happens to a signal when there is no modulation?
How will you produce an AM signal?
AM is achieved by multiplying carrier and message signals. Demodulation is achieved by sampling the AM signal at carrier frequency. Amplitude modulation (AM) is defined as modifying the amplitude of the carrier wave according to the message or information signal.
What is the effect on received signal in AM if the modulating signal amplitude is more than the carrier amplitude?
When the amplitude of the modulating signal is greater than the amplitude of the carrier, distortion will occur. 5. What is the effect of distortion? Explanation: Distortion occurs when the modulating signal amplitude is greater than the amplitude of the carrier, causing incorrect information to be transmitted.
What is the problem with the AM signal when it is over modulated?
If over-modulation does occur the carrier is chopped up and the modulation no longer resembles its modulating signal. At the receiving end the signal will be very distorted and unreadable – but more important, the over-modulated signal will have an increased bandwidth and will be rich in unwanted harmonics.
What is the difference between AM and FM waves?
The difference is in how the carrier wave is modulated, or altered. With AM radio, the amplitude, or overall strength, of the signal is varied to incorporate the sound information. With FM, the frequency (the number of times each second that the current changes direction) of the carrier signal is varied.
What happens to the AM waveform during the demodulation process?
In the demodulation process the audio or other signal carried by amplitude variations on the carrier is extracted from the overall signal to appear at the output. As the most common use for amplitude modulation is for audio applications, the most common output is the audio.
How does an AM modulator work?
If an input signal’s height varies with the loudness of a user’s voice and then adds this to the carrier, then the carrier’s amplitude will change corresponding to the input signal that’s been fed into it. This is called amplitude modulation or AM.
What happens to the modulation index of an AM signal if the modulating signal voltage is higher than the carrier signal voltage?
Multiplying the modulation index (m) by 100 gives the percent modulation. When the peak voltage of the modulating signal (V m) exceeds the peak voltage of the unmodulated carrier (Ve) overmodulation will occur, resulting in distortion of the modulating (baseband) signal when it is recovered from the modulated carrier.
What are the advantages of AM over FM signal?
Pros and Cons of AM vs. FM. The advantages of AM radio are that it is relatively easy to detect with simple equipment, even if the signal is not very strong. The other advantage is that it has a narrower bandwidth than FM, and wider coverage compared with FM radio.
How does the bandwidth of an AM signal relate to the information signal?
In other words the bandwidth occupied by the AM signal is twice the maximum frequency of the signal that is used to modulated the carrier, i.e. it is twice the bandwidth of the audio signal to be carried.
What is effect of change in modulating signal frequency on modulation index?
The carrier deviates maximum from its normal value. The frequency of a carrier will decrease as the amplitude of the modulating (input) signal decreases….Difference between Amplitude Modulation and Frequency Modulation.
|Amplitude Modulation||Frequency Modulation|
|More liable to noise||Less liable to noise|
How does an AM radio work?
Radio works by transmitting and receiving electromagnetic waves. In AM (Amplitude Modulation) radio, the strength (amplitude) of the signal is changed (modulated) to make the sounds. In FM (Frequency Modulation) radio, it is the speed (frequency) of the signal that is changed.
Why do AM radio signals change at sunset?
This change in AM radio propagation occurs at sunset due to radical shifts in the ionospheric layers, which persist throughout the night. During daytime hours when ionospheric reflection does not occur to any great degree, AM signals travel principally by conduction over the surface of the earth.
How does AM signal travel over the Earth?
During daytime hours when ionospheric reflection does not occur to any great degree, AM signals travel principally by conduction over the surface of the earth. This is known as “groundwave” propagation. Useful daytime AM service is generally limited to a radius of no more than about 100 miles (162 km), even for the most powerful stations.
What happens to a signal when there is no modulation?
Under these circumstances the signal level falls to zero and rises to twice the value with no modulation. In this case the voltage rises to a maximum of twice the normal level – this means that the power will be four times that of the quiescent value, i.e. 2 2 the value of the no modulation level.
How is amplitude modulation used in a radio signal?
Fig 1: An audio signal (top) may be carried by a carrier signal using AM or FM methods. Amplitude modulation ( AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave.