Harris RF-7800W Manuale utente
Table of Contents
Chapter 1 Introduction 1
a. History and Timeline of Radio Communication
b. Antenna Characteristics
- OMNI Directional vs. Directional
c. Frequency Range of Operations and Common Ranges
d. IEEE Standard 802.16/WiMAX vs. 802.11
Chapter 2 Harris RF-7800W System & BlueSky 15 Meter Mast Overview 13
a. Equipment Specifications
b. Components
c. BlueSky 15 Meter Mast Layout
Chapter 3 7800W Radio Programming 25
a. Recovery
b. Cut Sheets
c. Programming 7800W Radio
- Web Interfacing/GUI
d. 7800W Radio Operation
Chapter 4 System installation 39
a. Safety
b. Site Survey
c. BlueSky Mast Setup
d. Grounding
e. Antenna Orientation
Chapter 5 Lab 67
a. GUI
b. Ping
c. Phone Call - Table Top vs. Radio Link
Chapter 6 Additional Information 71
a. Specifications for the 7800W
b. Tunnel Architecture
c. Software Upgrade
d. Link Budget Tool
e. Glossary
TAB
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Introduction
2
3
History
Guglielmo Marconi
Inventor of the “wireless” Receiver-Transmitter
1873 – James Clerk Maxwell published his Treatise on Electricity and
Magnetism, setting forth the basic theory of electromagnetic wave propagation.
1888 - Heinrich Rudolph Hertz detected the first radio waves. He demonstrated
that disturbances generated by a spark coil showed the characteristics of
Maxwell’s radio waves.
1891 - Guglielmo Marconi invented the first “wireless” Receiver-Transmitter using
Morse Code.
1896 – Marconi communicated messages over distances of a few kilometers.
1901 - In Newfoundland, Canada, Marconi detected a telegraphic signal
transmitted from Cornwall, England 3000 kilometers away.
1908 - Frequency Hop was studied.
1912 – The sinking of the Titanic became the worst maritime disaster in history.
There had been a ship capable of rescue only 4 miles away, but the radio
operator was “off duty”. Due to this incident, ships are required to have 24-hour
radio watch.
4
1917 - The U.S. Army started using radios as they entered WWI.
1924 - Edward Appleton proved that the blanket of electrically charged (Ionized)
particles in the earth’s atmosphere (Ionosphere) was capable of reflecting radio
waves. In the late 1920’s, Scientists applied this theory and developed ways to
measure and predict the refractive properties of the ionosphere.
1942 - Hedy Lamarr and George Antheil received a patent for Frequency Hop.
After it was patented, the government used frequency hop as top-secret
communications until the 1980’s. Today, this secure communications method is
used in SINCGARS radio systems
5
Antennas
• Transmit and/or receive electromagnetic waves
• Varies in shape and size depending on the type of wave it
transmits/receives
An antenna is a passive device, which does not offer any added power to the
signal. Instead, an antenna simply redirects the energy it receives from the
transmitter. The redirection of this energy has the effect of providing more
energy in one direction, and less energy in all other directions.
An antenna gives the wireless system three fundamental properties: gain,
direction, and polarization.
6
Antenna Characteristics
Gain is a measure of increase in power and is the amount of increase in energy
that an antenna adds to a radio frequency (RF) signal.
Direction is the shape of the transmission pattern. As the gain of a directional
antenna increases, the angle of radiation usually decreases. This provides a
greater coverage distance, but with a reduced coverage angle. The coverage
area or radiation pattern is measured in degrees and is called beam width.
Beam widths are defined in both horizontal and vertical plains. Beam width is the
angular separation between the half power points (3dB points) in the radiation
pattern of the antenna in any plane. Therefore, an antenna has horizontal beam
width and vertical beam width.
Polarization is the physical orientation of the element on the antenna that emits
the RF energy.
7
Omni Directional - Radiation Pattern
Omni Directional Antennas use Vertical Polarization
Pros
Point to multi-point connections are best
Provides 360 degree area coverage
Easy installation and mounting
Cons
Limited distance (military use – 35 miles optimum terrain; 25 miles in difficult
terrain)
Poor coverage below the antenna
Indice
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