Advantages of Standard Amplitude Modulation
The following are the advantages of Standard Amplitude Modulation :
- AM transmitters are less complex .
- AM receivers are simple, detection is easy .
- AM receivers are cost efficient .
- AM waves can travel a longer distance .
- Low bandwidth
Applications of AM
- Radio broadcasting
- Picture transmission in a TV system
Disadvantages of Standard Amplitude Modulation
The disadvantages of standard Amplitude modulation or DSB-FC (Double sideband – Full Carrier ) system are as follows :
- Power wastage takes place in DSB-FC transmission
- DSB-FC system is bandwidth inefficient system
- AM wave gets affected due to noise
Now we will discuss each one in detail .
Power wastage in DSB-FC transmission
The carrier signal in the DSB-FC system does not convey any information . The information is contained in the two sidebands only .
But, the sidebands are images of each other and hence both of them contain the same information .
Thus, all the information can be conveyed by only one sideband .
As we know that the total power transmitted by an AM wave is given by :
Out of these three terms in the above equation , the carrier component does not contain any information and one sideband is redundant . Hence, out of the total power, the wasted power is given by :
This shows that we have to transmit much higher power than what is actually required . Hence, DSB-FC system is a power inefficient system .
Bandwidth Requirement of DSB-FC
The bandwidth (BW) of DSB-FC system is 2fm . This is due to the simultaneous transmission of both the sidebands, out of which only one is sufficient to convey all the information .
Thus, the BW of DSB-FC is double than actually required and therefore, DSB-FC is a bandwidth inefficient system .
Effect of Noise
When the AM wave travels from the transmitter to receiver over a communication channel, noise gets added to it .
The noise changes the amplitude of the envelope of AM in a random manner .
As the information is contained in the amplitude variations of the AM wave, the noise will contaminate the information contents in the AM .
Hence, the performance of AM is very poor in presence of noise .