Receiver Sensitivity vs analogue modulation technqiues

[kamranraja222]

Hello everyone,

I wish to know the dependence of receiver sensitivity over analogue modulation techniques(AM or FM). As per my knowledge If we know the NF of the receiver, desired output SNR and bandwidth of the receiver, we can easily calculate the sensitivity of the receiver at input. My concern is whether the sensitivity of the receiver depends upon the modulation frequency, modulation index(in case of AM), Frequency deviation(in case of FM) or not? If yes than how?? Thanks and best regards

 

[vfone]

AM sensitivity is more susceptible to noise because noise affects amplitude.
FM modulation is less susceptible to noise because information is transmitted through varying the frequency, and not the amplitude.

 

[c_mitra]

FM modulation is less susceptible to noise because information is transmitted through varying the frequency, and not the amplitude

It really depends on the noise frequency bandwidth at the receiving frequency. However, amplitude modulation also causes frequency modulation. The nomenclature is really notional.

 

[albbg]

You could be interested in the following lecture note:

https://nptel.ac.in/courses/106106097/pdf/Lecture25-26_NoiseAMFM.pdf

The sensitivity is defined as the minimum level to have a defined level of SINAD (Signal to Noise And Distortion), equivalent to the BER of the digital world. A usual value for SINAD is in the 10 - 12 dB range measured at 1kHz modulation frequency. This value of SINAD theorically correspond to an intellegible demodulated speech.

 

[vfone]

For the same RX bandwidth FM is less affected by the noise than AM.
The percent of the parasitic AM of an FM signal, and the parasitic FM of an AM signal, is insignificant when is about noise analysis
In any given (and equivalent) noisy conditions, FM is better than AM.