In olden days all radio stations followed only amplitude modulation to propagate the signals.
Presently still some of the radio stations follow the same and mostly have switched over to frequency modulation.
Especailly in tv transmission the picture signal is propagated only by amplitude modulation.
QAM is a combination of phase modulation & amplitude modulation.
the maximum amplitude of carrier wave varied with respect to instantaneous values of message signal is called amplitude modulation
In Frequency Modulation (FM), if the modulation frequency is doubled, the modulation index does not necessarily double; it depends on the amplitude of the modulating signal. In Amplitude Modulation (AM), the modulation index is defined as the ratio of the peak amplitude of the modulating signal to the carrier amplitude, so it remains unchanged with varying modulation frequency. For Phase Modulation (PM), similar to FM, the modulation index is influenced by the amplitude of the modulating signal and does not inherently double with the modulation frequency. Thus, modulation frequency and modulation index are not directly linked in this way for FM, PM, or AM.
AM imply amplitude modulation of a carrier signal
because noise usually changes the amplitude not frequency.
AM - Amplitude Modulation FM - Frequency Modulation
QAM is a combination of phase modulation & amplitude modulation.
In amplitude modulation, modulation depth refers to the ratio of the unmodulated carrier amplitude to the amplitude deviation for which the modulated carrier wave reaches its minimum value. If this minimum value is zero, the modulation depth is 100%.For amplitude modulation,modulation depth = (a-b)/(a+b),wherea is the unmodulated carrier amplitude, andb is the minimum amplitude deviation.The modulation depth ratio is also referred to as the modulation index.
amplitude modulation is where we modulate our signal with a carrier signal amplitude changes but frequency remains constant in amplitude modulation
Frequency modulation have some advantages over amplitude modulation, FM is not sensitive to the amplitude noise, and have high efficient use of transmitted power
Normal frequency range for amplitude modulation is 550kHz to 1610kHz
In amplitude modulation, modulation depth refers to the ratio of the unmodulated carrier amplitude to the amplitude deviation for which the modulated carrier wave reaches its minimum value. If this minimum value is zero, the modulation depth is 100%.For amplitude modulation,modulation depth = (a-b)/(a+b),wherea is the unmodulated carrier amplitude, andb is the minimum amplitude deviation.The modulation depth ratio is also referred to as the modulation index.
Amplitude modulation is a method of sending information by modifying the intensity of a carrier wave.
the maximum amplitude of carrier wave varied with respect to instantaneous values of message signal is called amplitude modulation
In Frequency Modulation (FM), if the modulation frequency is doubled, the modulation index does not necessarily double; it depends on the amplitude of the modulating signal. In Amplitude Modulation (AM), the modulation index is defined as the ratio of the peak amplitude of the modulating signal to the carrier amplitude, so it remains unchanged with varying modulation frequency. For Phase Modulation (PM), similar to FM, the modulation index is influenced by the amplitude of the modulating signal and does not inherently double with the modulation frequency. Thus, modulation frequency and modulation index are not directly linked in this way for FM, PM, or AM.
Amplitude Modulation (AM) Frequency Modulation (FM)
AM imply amplitude modulation of a carrier signal