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
AM imply amplitude modulation of a carrier signal
because noise usually changes the amplitude not frequency.
Pulse-Amplitude Modulation
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
Amplitude Modulation (AM) Frequency Modulation (FM)
AM imply amplitude modulation of a carrier signal
low level amplitude modulation occurs when the carrier signal is first modulated and then amplified,whereas in high level modulation,the carrier signal is first amplified and then is modulated.