AM radio:
AM means Amplitude Modulation. It is the amplitude that is modified. AM has the poor sound quality in comparison to the FM radio and it is cheap as well. It was invented in the year 1906. It is broadcasted in mono.
FM radio:
FM is the Frequency Modulation. In FM radio it is the frequency that undergoes modification. It was invented in the year 1933. It is broadcasted in stereo.
Differences:
| Basis | AM radio | FM radio |
|---|---|---|
| Definition (www.oxforddictionaries.com) |
Plural form of tooth. | FM broadcasting is a VHF broadcasting technology, pioneered by Edwin Howard Armstrong, which uses frequency modulation (FM) to provide high-fiedlity sound broadcast radio. |
| Full Forms | AM means Amplitude Modification. | FM means Frequency Modulation. |
| Pronunciation |
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| Origin | AM method of audio transmission was first successfully carried out in the mid 1870s. | FM radio was developed in the United states in the 1930s, mainly by Edwin Armstrong. |
| Frequency Range | AM radio ranges from 535 to 1705 KHz (OR) Up to 1200 bits per second. | FM radio ranges in a higher spectrum from 88 to 108 MHz. (OR) 1200 to 2400 bits per second. |
| Bandwidth Requirements | Twice the highest modulating frequency. In AM radio broadcasting, the modulating signal has bandwidth of 15kHz, and hence the bandwidth of an amplitude-modulated signal is 30kHz. | Twice the sum of the modulating signal frequency and the frequency deviation. If the frequency deviation is 75kHz and the modulating signal frequency is 15kHz, the bandwidth required is 180kHz. |
| Complexity | Transmitter and receiver are simple but syncronization is needed in case of SSBSC AM carrier. | Tranmitter and reciver are more complex as variation of modulating signal has to beconverted and detected from corresponding variation in frequencies.(i.e. voltage to frequency and frequency to voltage conversion has to be done). |
| Noise | AM is more susceptible to noise because noise affects amplitude, which is where information is “stored” in an AM signal. | FM is less susceptible to noise because information in an FM signal is transmitted through varying the frequency, and not the amplitude. |
| Cost | It can be purchased at low cost. | It is more expensive in comparison to the FM radio. |
| Advantages/Benefits | The main advantages of AM radio are it is cheaper along with that it can be transmitted over long distances. | FM has better sound quality due to higher bandwidth. |
| Disadvantages | AM has poor sound quality compared with FM. | FM signals are impacted by physical barriers. |
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