AM radio VS. PM radio

AM radio (AM stands for Amplitude Modulation) and PM radio (PM stands for Phase Modulation) are two different types of radio transmission technologies. Both AM and PM radio use electromagnetic waves to transmit audio signals over long distances, but they differ in the way the information is encoded onto the wave.

Purposes

The primary purpose of AM radio is to transmit low-fidelity audio signals over medium to long distances, while PM radio is designed for transmitting high-fidelity audio signals over shorter distances.

Characteristics

1. AM radio: AM radio uses amplitude modulation, where the amplitude (height) of the radio wave is varied in proportion to the audio signal. This makes AM radio susceptible to interference from static electricity and other radio signals. AM radio signals also have a narrower bandwidth compared to PM radio signals, which means they can suffer from frequency crowding. The audio quality of AM radio is usually poorer than that of PM radio due to the lower frequency of transmission (535-1705 kHz) and the susceptibility to interference. Examples of AM radio stations include talk radio, news radio, and sports radio.

2. PM radio: PM radio uses phase modulation, where the phase of the radio wave is varied in proportion to the audio signal. This makes PM radio less susceptible to interference from static electricity and other radio signals. PM radio signals also have a wider bandwidth compared to AM radio signals, which allows for more channels to be used in the same frequency range. The audio quality of PM radio is generally higher than that of AM radio due to the higher frequency of transmission (87.5-108 MHz) and the reduced susceptibility to interference. Examples of PM radio stations include music radio, talk radio, and news radio.

Key differences

1. Modulation method: The primary difference between AM and PM radio is the method used for encoding the audio signal onto the radio wave. AM radio uses amplitude modulation, while PM radio uses phase modulation.

2. Susceptibility to interference: AM radio is more susceptible to interference from static electricity and other radio signals, while PM radio is less susceptible.

3. Bandwidth: AM radio signals have a narrower bandwidth compared to PM radio signals.

4. Audio quality: Due to the higher frequency of transmission and reduced susceptibility to interference, PM radio generally provides better audio quality than AM radio.

Tips

If you are trying to listen to an AM radio station and are experiencing interference, you can try using a more sensitive radio or repositioning the antenna for better reception. For PM radio, you can use an external antenna to improve signal strength and reception quality.