MICROWAVE LINK COMMUNICATION SYSTEM
INTRODUCTION
Communications is the process of sending and/or receiving data, signal or information through the help of the different media.
TYPES OF COMMUNICATION
Wired Communication
Wireless Communication
MICROWAVE LINK DESIGN CONSIDERATIONS
In putting up microwave links, the different considerations are made:
Site Selection Equipment selection Tower Selection Power Equipment Lightning Protection
SITE SELECTION
In locating the sites, the following factors should be considered: Terrain mapping for possible obstructions; Geographical location, for possible line-of-sight
path obstruction; Adequate source of power and water; Population on each site and; Be in the vicinity of any popular landmark or a
City in the region. The proponents also considered the topographic
map of every province covered by Region 3 for establishment of each site.
EQUIPMENT SELECTION
Microwave Antenna
The microwave antenna that is to be chosen:
Must have high antenna gain; And must not be too heavy and large for easy
mounting in the tower.
EQUIPMENT SELECTION
microwave radio that is to be chosen must have:
A frequency at which the links is to be operated; low receiver sensitivity value; High transmitted output power; An indoor and outdoor unit installation for
eliminating the use of waveguides for transmission;
And must be a user-friendly interface for simple maintenance management.
EQUIPMENT SELECTION
Automatic Transfer Switch The ATS must have the ability to be switched on
and off to different sources that is the main power source and the backup source.
Air Conditioning Unit The site must contain an air conditioning unit for
proper cooling and must accommodate the whole room to maintain the proper temperature in which all the equipments are stored so that overheating and malfunctioning of the equipments is prevented.
TOWER SELECTION
The tower used must possess the following: The capability of the tower to hold loads such as
antennas and cables prior to construction; The type of soil wherein the tower is raised must
also be considered for any ground movement to prevent the tower from swaying;
The height of the tower must be enough in order to avoid obstructions;
The anticipated wind loading was identified under harsh condition and additional loading.
A stand – by power equipment should be provided for possible power interruptions at the microwave site to maintain operation.
Generator
Uninterruptible Power Supply
POWER EQUIPMENT
LIGHTNING PROTECTION
The lightning protection that will be used must contain the appropriate conductive paths for lightning currents and be able to disperse atmospheric discharge in order to prevent surge current to enter the equipments and sustain safety in the facility.
GROUNDING PROTECTION
The grounding equipment must be installed at every equipment inside the facility and must be coordinated with the lightning protection in order to prevent abrupt surge entering to the equipments thus making the equipments safe.
OBSTRUCTION LIGHTING
21 feet – 120 feet: Use 2 obstruction lights;
151feet – 300 feet: Use 2 obstruction lights at one-half way level of
the tower & a beacon light at the top of the tower;
301 feet – 405 feet Use 2 obstruction lights at 2/3 way level and a
beacon at the top; 405 feet and above
Use various light combinations stated.
SAMPLE DESIGN
The following are the objectives of the design:
To construct a feasible microwave link between: Bamban, Hermosa, Bataan (Site 1) and Pulung Bulu, Angeles City, Pampanga(Site 2) with the frequency of 5Ghz;
To achieve an overall system reliability of 99.999999%;
PATH PROFILE
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Ele
vati
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Distance
Site 1
Site 2
FREQUENCY ASSIGNMENT
GREAT CIRCLE DISTANCE CALCULATION
The formula in getting the Great Circle Distance is as follows:
A = |LONGITUDE 2 - LONGITUDE 1|b = 90° - LATITUDE 1c = 90° - LATITUDE 2cos a = (cos b) (cos c) + (sin b) (sin c) (cos A)
Conversion factor: 1° = 60 nautical mile1 nautical mile = 1.151 statute mile1 statute mile = 1.609 kilometre
COMPUTATIONS:
Known DataSite Longitude Latitude
A. Bamban, Hermosa, Bataan
120°25’28.33” 14°48’31.96”
B. Pulung Bulu, Angeles City,
Pampanga120°36’12.07” 15°8’1.95”
COMPUTATIONS:
ANTENNA ORIENTATION CALCULATION
Where: C = difference of the longitudinal coordinates of the sites in a hop X = the computed coordinate of the first site Y = the computed coordinate of the second site
ANTENNA ORIENTATION CALCULATION
ANTENNA ORIENTATION CALCULATION
ANTENNA HEIGHT CALCULATION
ANTENNA HEIGHT CALCULATION
FRESNEL ZONE SHOWING ANTENNA HEIGHTS OF THE LINK
TRANSMISSION CALCULATION
The calculation of the power dissipation at certain points in the system wherein we can determine at what level of the signal will be received by the receiver part of the microwave link. The points are as follows:
PT = P1
P2 = PT – TLLTX
P3 = P2 + AGTX
P4 = P3 – FSLP5 = P4 + AGRX
P6 = P5 – TLLRX = RSL
TRANSMISSION CALCULATION
TRANSMISSION CALCULATION
LINK BUDGET OF HOP
P1 P2 P3 P4 P5 P6
-100
-80
-60
-40
-20
0
20
40
60
80
RELIABILITY CALCULATIONS
Where: = expected outage time = the percent of time that the system is expected to operate
without an outage.
RELIABILITY CALCULATIONS
RELIABILITY CALCULATIONS
RELIABILITY CALCULATIONS
Reliability using Vigants and Barnette Method
RELIABILITY CALCULATIONS
REFLECTION POINT CALCULATION
The formulas for getting the reflection point are:
REFLECTION POINT CALCULATION
REFLECTION POINT CALCULATION
REFLECTION POINT OF HOP 1