Avlite AvMesh, Руководство по установке и устранению неисправностей

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AvMesh ® RF Communications Systems
Installation & Service Manual
Latest products and information available at www.avlite.com 7
3.0 RF Fundamentals
3.1 Elements of a Radio Frequency communications system
A typical radio frequency communication system consists of the following elements:
• Transmitter
- Feeds the signal to a transmitting antenna by first encoding the data
into RF waves (signals) with a certain signal strength (known as the power output) to
project the signal to the receiver.
• Receiver - Accepts and decodes the RF signals that come through the receiving
antenna and rejects unwanted ones via the use of a filter.
• Environment - The physical space between the transmitter and receiver over which
the radio waves propagate. The environment through which communication is
occurring can be affected by interference and physical obstructions such as walls,
buildings and vegetation.
• Antennas or other focusing elements - Devices that focus the radio frequency
energy in a particular direction.
Figure 2: Radio Communications System
In radio frequency communication, electromagnetic waves (signals) are created and
radiated from a source (i.e. transmitting antenna at the transmitter) and then travel through
the air at the speed of light after which they are picked up at a particular destination (i.e.
receiving antenna at the receiver). The higher the frequency of an electromagnetic wave
(signal), the shorter the wavelength. Signals with longer wavelengths are typically able
to travel a greater distance and bend around objects better than signals with shorter
wavelengths.
Figure 3: Wavelength is inversely proportional to frequency
Transmitter
Receiver
Transmitter
Receiver
Transmitting
Antenna
Receiving
Antenna
Environment
Transmitter
Receiver
Transmitting
Antenna
Receiving
Antenna
Environment
Lower frequency-
longer wavelength
Lower frequency-
longer wavelength
Higher frequency-
shorter wavelength
Higher frequency-
shorter wavelength
Higher frequency-
shorter wavelength
Lower frequency-
longer wavelength
Lower frequency-
longer wavelength
Higher frequency-
shorter wavelength
Higher frequency-
shorter wavelength
Higher frequency-
shorter wavelength