Table of Contents
Which of the following is a method for retrieving the original modulating signal from an AM signal?
Demodulation
Demodulation is a key process in the reception of any amplitude modulated signals whether used for broadcast or two way radio communication systems. Demodulation is the process by which the original information bearing signal, i.e. the modulation is extracted from the incoming overall received signal.
What would happen if a 1 kHz signal amplitude modulate a 1 kHz carrier signal?
Sidebands. It is possible to plot the frequency spectrum of an AM transmission using a spectrum analyser. If a 1 kHz sine wave tone is modulated onto a 1 MHz carrier, two sidebands will be produced 1 kHz above and 1 kHz below the 1 MHz carrier signal.
Which device is used to remove the carrier wave leaving only the original signal?
Unsourced material may be challenged and removed. Demodulation is extracting the original information-bearing signal from a carrier wave. A demodulator is an electronic circuit (or computer program in a software-defined radio) that is used to recover the information content from the modulated carrier wave.
What change is carried out in amplitude modulation?
In AM, the voltage or power level of the information signal changes the amplitude of the carrier in proportion (see Fig. 7.7). With no modulation, the AM carrier is transmitted by itself.
Why the carrier signal doesn’t carry any information?
The frequency of a radio or television station is considered to be the carrier frequency. However the carrier itself is not useful in transmitting the information, so the energy in the carrier component is a waste of transmitter power. Therefore, in many modern modulation methods, the carrier is not transmitted.
What is carrier signal and modulating signal?
In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a separate signal called the modulation signal that typically contains information to be transmitted.
How does the carrier amplitude vary in AM?
In AM, the carrier does not vary in amplitude. However, the modulating data is in the form of signal components consisting of frequencies either higher or lower than that of the carrier. The signal components are known as sidebands and the sideband power is responsible for the variations in the overall amplitude of the signal.
What is the difference between carrier and modulating waves?
The first figure shows the modulating wave, which is the message signal. The next one is the carrier wave, which is a high frequency signal and contains no information. While, the last one is the resultant modulated wave.
How is message signal extracted from amplitude modulated wave?
The carrier wave which has a much higher frequency than the message signal carries the information. At the receiving station, the message signal is extracted from the amplitude modulated wave by demodulation technique. Consider a sinusoidal modulating signal or message signal (am) of frequency (ωm) and amplitude (Am) given by:
How to calculate the modulation index of a signal?
Hence, one can easily calculate the modulation index, when the amplitudes of the two signals are known. We can also determine the modulation index with the help of modulated wave. Assume, A max to be the maximum amplitude of the modulated signal and A min to be the minimum amplitude of the modulated signal.