WHY CAN AM broadcasts be heard for a great distance under certain conditions?
Because of their longer wavelengths, AM waves reflect off a layer of the upper atmosphere called the ionosphere. You can see how this happens in the Figure below. Because the waves are reflected, they can reach radio receivers that are very far away from the radio tower.
Why are AM radio stations able to reach further distances?
In contrast to line-of-sight propagation, at low frequency (below approximately 3 MHz) due to diffraction, radio waves can travel as ground waves, which follow the contour of the Earth. This enables AM radio stations to transmit beyond the horizon.
Why do AM signals travel farther at night?
However, during nighttime hours the AM signals can travel over hundreds of miles by reflection from the ionosphere, a phenomenon called “skywave” propagation. Most of these stations are also required to reduce power at night, to avoid causing interference to the dominant stations and to each other.
Why do AM radio waves travel farther than FM?
Without interference, radio waves travel in a straight line from the broadcast source, ultimately hitting the ionosphere. For AM waves, given the right conditions, they will essentially bounce back and forth between the ground and the ionosphere, propagating the signal farther and farther.
What happened to AM radio?
Seems so retro, but it is still useful. Nevertheless, AM radio has been in decline for years, with many AM stations going out of business each year. Now there are only 4,684 left as of the end of 2015. Most of the listeners moved on to FM or other radio sources.
What are the disadvantages of listening to AM radio?
The major disadvantage of AM is that the signal is affected by electrical storms and other radio frequency interference. Also, although the radio transmitters can transmit sound waves of frequency up to 15 kHz, most receivers are able to reproduce frequencies only up to 5kHz or less.
What is the bandwidth requirement for AM radio?
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.
Why is am preferred over FM in long distance communication?
If we talk about the bandwidth of AM then it is 1071KHz and bandwidth of FM is 20.5 MHz.According to the bandwidth FM should be used for long distance transmission but it is not usedfor long distance but AM is used fir long distance transmissions.
How many kHz does an AM radio station transmit?
16) An AM broadcast station transmits modulating frequencies up to 6 kHz. If the AM station is transmitting on a frequency of 894 kHz, the values for maximum and minimum upper and lower sidebands and the total bandwidth occupied by the AM station are: