Contents
What determines signal bandwidth?
The bandwidth of a signal is defined as the difference between the upper and lower frequencies of a signal generated. As seen from the above representation, Bandwidth (B) of the signal is equal to the difference between the higher or upper-frequency (fH) and the lower frequency (fL).
HOW AM signal is generated?
AM generation involves mixing of a carrier and an information signal. In low level modulation, the message signal and carrier signal are modulated at low power levels and then amplified. The advantage of this technique is that a small audio amplifier is sufficient to amplify the message signal.
Why carrier is used to transmit the information signal?
The purpose of the carrier is usually either to transmit the information through space as an electromagnetic wave (as in radio communication), or to allow several carriers at different frequencies to share a common physical transmission medium by frequency division multiplexing (as in a cable television system).
Which signal has wider bandwidth?
A square wave has more “bandwidth” if you consider both waves as having the same fundamental frequency. The fundamental frequency if taken to be more or less approximate to a real sine wave, will then “narrowly” allow sine waves to pass.
How is the frequency of a multiplying signal found?
Since the time domain signals are multiplied, the corresponding frequency spectra are convolved. That is, (f) is found by convolving (b) & (d). Since the spectrum of the carrier is a shifted delta function, the spectrum of the modulated signal is equal to the audio spectrum shifted to the frequency of the carrier.
What is the process of multiplying radio waves?
For instance, if a 100 volt, 1 MHz sine wave is fed into an antenna, the resulting radio wave can be detected in the next room, the next country, and even on the next planet. Modulation is the process of merging two signals to form a third signal with desirable characteristics of both.
One side of this was discussed in the last chapter: time domain signals can be convolved by multiplying their frequency spectra. Amplitude modulation is an example of the reverse situation, multiplication in the time domain corresponds to convolution in the frequency domain.
What is the process of merging two signals?
Modulation is the process of merging two signals to form a third signal with desirable characteristics of both. This always involves nonlinear processes such as multiplication; you can’t just add the two signals together.