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advantages of am

时间:04-10 整理:3721RD 点击:
What are the advantages and disadvantages of AM and FM modulation?
With regards

Ajish Babu S

Hello!

- Advantage of AM

1- Corverage area of AM Reciever is wider than FM because atmospheric propagation
2- AM is long distance propagation because λ
3- AM Circuit is cheapter and non complex than FM.
4- AM have bandwidth limited and FM unlimited
- Disadvantage of AM

1- The only one way to withance to noise happen is increasing power transmite
2- Signal of AM is not stronger than FM when it propagate to obstacle. (Urband)
3- Only one sideband of AM transmites Information Signal, So it loss power on other sideband and Carrier.
4- Noise mixes AM Signal in amplitude when it propagates in free space that it make difficulty to recover Original Signal at reciever.

Your sincerely,


I am sorry, but I can agree only with point 3 from Disadvantage.
In my opinion all the others are wrong.

One big advantage of FM is that you can run the PA in Compression and/or
Saturation Mode. With AM you care about the linearity

one main advantage of the FM is low noise compare to AM

and we dont need any amplitude limitter circuit in AM where as in FM we need an amplitude limitter ckt.

For AM, linear amplifiers are rarely used because of their poor efficiency. Most high level AM modulation transmitters use a class C (non-linear) RF amplifier. Newer ones use switcher PA (Class E, F, etc) which are also non-linear. In the non-linear cases, the audio is injected by modulating the DC power supply of the non-linear RF amplifier.

So a class C amplifier works equally well for AM or FM. However, if you are high level AM modulating the class C amplifier, you would need an audio amplifier that supplies the additional audio sideband power. This is not needed for FM.

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