Microwave link communication system

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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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