Disadvantage of angular modulation, such as frequency modulation (FM) or phase modulation (PM), includes its susceptibility to noise and interference, which can degrade signal quality and lead to distortion. Additionally, angular modulation typically requires more bandwidth compared to amplitude modulation (AM), making it less efficient in terms of spectrum usage. The complexity of demodulating angularly modulated signals also increases, necessitating more sophisticated receiver designs.
One disadvantage of the standard amplitude modulation system is that 67% of the power is used for the carrier, but the carrier transmits no information, so it can be considered as wasted power.The 34% remaining power is split between two mirror opposite sidebands so, in effect, you really only have 17% of your power used to carry the signal.
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.
the modulation system is of FM
QAM is a combination of phase modulation & amplitude modulation.
Frequency modulation Phase modulation
The difference between frequency modulation and phase modulation is that with frequency modulation the angular frequency of the signal is modified while with the phase modulation, the phase angle of the signal is modified.
It is called angle modulation because it changes the angle of the carrier which is exponential, e.g. sin theta = {(e*j theta + e (-j theta)} / 2
One disadvantage of the standard amplitude modulation system is that 67% of the power is used for the carrier, but the carrier transmits no information, so it can be considered as wasted power.The 34% remaining power is split between two mirror opposite sidebands so, in effect, you really only have 17% of your power used to carry the signal.
Advantage - 1. Phase modulation & demodulation is easy compared to Frequency modulation. 2. Phase modulator is used in determining velocity of moving target by extracting Doppler information. Doppler information needs stable carrier which is possible in phase modulation but not in frequency modulation. Disadvantage - 1. Phase ambiguity comes if we exceed its modulation index pi radian(180 degree). 2. we need frequency multiplier to increase phase modulation index. Visit my website http://harshit.org
AM - Amplitude Modulation FM - Frequency Modulation
modulation
Frequency Modulation and Phase Modulation
frequency modulation..
due to velocity modulation density modulation occurs in TWT
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.
the modulation system is of FM
advantage-its a base for all the digital modulation technique disadvantage- 1.since amplitude keeps varying so there is noise associated with it. 2.due to nyquist criteria its require high bandwidth. 3.due to amplitude variation peek power of receiver also varies with it nitesh