I'm currently doing a project which is related to marker beacon,
The circuit given is using a FM radio waves and I heard that in an airport they use AM radio waves.
Can anyone tell me either it is a FM or a AM?
Perhaps the answer can together with a link.
Thanks
The circuit given is using a FM radio waves and I heard that in an airport they use AM radio waves.
Can anyone tell me either it is a FM or a AM?
Perhaps the answer can together with a link.
Thanks
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Assuming you mean the NDB (non directional beacon), it is amplitude modulated (AM).
AM is also used in communications between aircraft and control tower.
The reason is that if 2 aircraft transmit at the same time, both signals will be noticed, even if one (or both) are unreadable.
The tower can then ask one of them to repeat the message, if able to identifying part of the transmission, then ask the second aircraft to repeat its message.
The problem with FM is that the stronger signal "captures" the frequency, and any other simultaneous transmission from another aircraft might nor be received at all. Thus, FM is NOT used for aircraft beacons or communications.
AM is also used in communications between aircraft and control tower.
The reason is that if 2 aircraft transmit at the same time, both signals will be noticed, even if one (or both) are unreadable.
The tower can then ask one of them to repeat the message, if able to identifying part of the transmission, then ask the second aircraft to repeat its message.
The problem with FM is that the stronger signal "captures" the frequency, and any other simultaneous transmission from another aircraft might nor be received at all. Thus, FM is NOT used for aircraft beacons or communications.
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Marker Beacon is a AM signal at 75 MHz. Search Google for ILS Instrument Landing System which includes, Marker Beacon, VOR, Glide Slope, and I forget the 4th one. With these signals you can land a plane automatically
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The marker is transmitted with AM. Tower communications is done with FM.