CTR20104.pdf

8/11/2019 CTR20104.pdf

1/103

Note: The source of the technical material in this volume is the Professional

Engineering Development Program (PEDP) of Engineering Services.

Warning: The material contained in this document was developed for Saudi

Aramco and is intended for the exclusive use of Saudi Aramcos

employees. Any material contained in this document which is notalready in the public domain may not be copied, reproduced, sold, given,

or disclosed to third parties, or otherwise used in whole, or in part,

without the written permission of the Vice President, Engineering

Services, Saudi Aramco.

Chapter : Communications For additional information on this subject, contact

File Reference: CTR20104 J. S. Phillips on 873 - 0228

Engineering EncyclopediaSaudi Aramco DeskTop Standards

Evaluating The Acceptability Of

A Proposed Narrowband Radio System

Design Or Modification

8/11/2019 CTR20104.pdf

2/103

Engineering Encyclopedia Communications

Evaluating the Acceptability of a Proposed Narrowband Radio Systems

Saudi Aramco DeskTop Standards

CONTENTS PAGES

TYPICAL ENGINEERING WORK PACKAGES (EWPS): PURPOSES

AND BASELINES.................................................................................................. 1

Purposes of EWPs ....................................................................................... 1

Baselines for EWPs ..................................................................................... 1

Problem Reports .............................................................................. 2

Parameters for System Configuration .............................................. 5

PREPARING AN EWP FOR DESIGN OF A TRANSMISSION PATH FOR

A NARROWBAND RADIO SYSTEM.................................................................. 7

Specific Purpose..........................................................................................7

Required Baseline Data and Information .................................................... 7

Required Analyses and Calculations ........................................................... 8

Point-to-Point Line-of-Sight Calculations ....................................... 9

Computerized Spreadsheet Calculations........................................ 14

Factors that Affect the Design of More Complicated

Transmission Paths ........................................................................ 17

Appropriate EWP Formats and Contents .................................................. 20

PREPARING AN EWP FOR EQUIPMENT MODIFICATIONS AND/OR

ADDITIONS FOR A NARROWBAND RADIO SYSTEM................................. 23

Specific Purpose........................................................................................23

Required Baseline Data and Information .................................................. 23

Options for Equipment Modifications and/or Additions ........................... 24

Base Station(s) ............................................................................... 24

Multiplex Equipment ..................................................................... 25

Controllers ..................................................................................... 26Antenna System ............................................................................. 27

Bridges...........................................................................................28

Appropriate EWP Formats and Content....................................................31

PREPARING AN EWP FOR DEVELOPMENT OR ALTERATION OF A

FREQUENCY PLAN FOR A NARROWBAND RADIO SYSTEM...................33

8/11/2019 CTR20104.pdf

3/103

8/11/2019 CTR20104.pdf

4/103



Saudi Aramco DeskTop Standards 1

TYPICAL ENGINEERING WORK PACKAGES (EWPS): PURPOSES AND

BASELINES

The following topics that pertain to typical EWPs are covered in this section:

Purposes of EWPs

Baselines for EWPs

Purposes of EWPs

An EWP can be viewed as the media through which resolutions to problems with narrowband

radio systems are formulated and expressed. For example, in the Evaluation for the first

Module of this course, systems that required expansion were identified. An EWP would be

used to detail the means and methods that would be used to implement the expansion.

EWPs serve specific purposes. Handouts 1 and 2 are sample EWPs that will be used to

illustrate the types of purposes that can be served by an EWP. Only the purposes of the

EWPs will be covered in this section. A more detailed examination that shows how the

formats and contents of the sample EWPs help to execute the purposes of the EWPs will be

performed in later sections of this Module.

Handout 1 is an EWP that was written to address a problem in which the coverage in the Ain

Dar area for the paging system needed to be improved. The specific purpose of this EWP is

to detail the steps that are required to increase the Abqaiq paging transmitter coverage in the

Ain Dar area.

Handout 2 is an EWP that addresses a problem in which helicopter pilots could not

communicate with personnel at Pump Station 6. The specific purpose of this EWP is to detail

the plans to provide the means for Saudi Aramco MEDIVAC helicopter crew to communicate

with personnel at Pump Station 6.

Baselines for EWPs

A baseline is the documentation that provides the problem that the EWP is to address. The

nature of the problem determines the source of the baselines. The following topics thatpertain to baselines for EWPs are covered in this section:

Problem Reports

Parameters for System Configuration

8/11/2019 CTR20104.pdf

5/103




Problem Reports

A problem report is a document that details the problems that are experienced by the users of

a narrowband communication system. For example, the problems that resulted in thedevelopment of the Handout 1 and 2 EWPs were reported through use of problem reports.

A Communications Service Request (Aramco Form 6934) is used to report communications

problems. Figure 1 is a Form 6934. Items 1 through 11 are completed by the organization or

individual that reports the problem. These items are completed before the form is submitted.

Items 12 through 14 are completed by Communications. The following information is

recorded by the organization or the individual that requests service:

Item 1 is titled "Location." This item identifies the location that requires

service. "Requesting Organization" identifies the organization or the individual

that requests service.

Item 2 is titled "Date Service is Required." This item is used to record the date

by which the service is required.

Item 3 is titled "Department/ Division Section/Unit." This item specifies the

organization that requests service.

Item 4 is titled "Organization Code." This item specifies the code of the

organization that requests service.

Item 5 is titled "Individual Receiving Service." Saudi Aramco employees enter

their name, badge number, and job title. Contractors enter only their name; the

badge number and job title spaces are left blank.

Item 6 is titled "Approved By." This item is used to record the name, title, box

number, and date of the required proponent approval.

Item 7 is titled "Custodian." If radio equipment is to be turned in, this item is

used to record the name, organization code and badge number of the individual

who is responsible for turning in the radio equipment. The date is also

recorded.

Item 8 is titled "Contact Name." This item is used to record the name of the

individual who is to be contacted by Communications to coordinate the work

and the location and phone number of the individual.

8/11/2019 CTR20104.pdf

6/103




Items 9 through 11 are titled "Type of Action," "Location of Work," and

"Description of Service Requested and Justification." The information that is

recorded in these items depends on the nature of the requested service.

Generally, if the Communications Service Request is used to report a problem,

the "Other" block in item 9 is checked.

The following information is recorded by the Customer Services Unit:

A service request control number is entered in the Control Number block at the

top of the form. This number is referenced in future inquiries as to the status of

the request. A priority also is assigned to the request. Requests that are from

VIPs and other essential users are designated as Priority A. All business

service requests, except those requests covered by Priority A, are designated as

Priority B. All residential requests for service, except those requests covered

by Priority A, are designated as Priority C.

Item 12 is titled "Received By: Name, Telephone No. and Date." The

individual who receives the request provides his name, telephone number, and

the date that the request is received.

Item 13 is titled "Customer Services Supervisor: Telephone and Date." This

item is used to record the signature, the telephone number, and the date of

approval by the Customer Services Supervisor.

Item 14 is titled "Approved by: Title and Date." This item is used to record the

signature, title, and date of final approval of the request for service.

Because the Communications Service Request states a problem from the perspective of the

system user, the description of the service that was requested and justification (Item 11)

provides baseline data that are used to generate an EWP. Again, EWPs address specific

problems; these problems are articulated in item 11 of the Communications Service Request.

8/11/2019 CTR20104.pdf

7/103




Communications Service Report

Figure 1

8/11/2019 CTR20104.pdf

8/103




Three example EWP's are contained in Handouts 1, 2, and 5. The following is some of the

pertinent information that is contained in the problem report that was a baseline for the EWP

contained in Handout 2:

The problem is stated; helicopter and ground control personnel are unable to

communicate.

Amplifying information is provided; the frequencies and systems that are used

by the various personnel are provided.

Justification for the need to solve the problem is provided; occasionally,

helicopters need to land at Pump Station 6.

Parameters for System Configuration

The following topics that pertain to how parameters for system configuration can serve as

baselines for EWPs are covered in this section:

Synopses of Identified Problems

Suggested Solutions

Synopses of Identified Problems - After a Communications Service Request or an

Engineering Study/Services Request has been submitted, further documentation that

can serve as a baseline for an EWP may be generated. An Engineering Study/Services

Request can be developed in response to a Communications Service Request. TheEngineering Study/Services Request is a document that can be used to order an

investigation into a problem that has been reported by a Communications Service

Request. Handout 5 contains an Engineering Study/Services Request and a

Communications Services Request that call for an investigation into a problem with

the Ras Tanura Refinery Radio System.

In response to an Engineering Study/Services Request, a study can be performed to

provide a synopsis of the identified problem. The purposes of these studies basically

are to isolate the cause of a problem through use of the steps of the systematic method

of troubleshooting a system-level problem. When the problem has been isolated, the

appropriate corrective action can be determined.

8/11/2019 CTR20104.pdf

9/103




Suggested Solutions - The studies that are used to provide a synopsis of the identified

problem conclude with a suggestion as to how the problem can be resolved. For

example, an Engineering Study/Services Request was issued to study the problem that

was addressed in the EWP contained in Handout 2. That is, a request was made to

Communications Engineering to study the communications problem between the

Saudi Arabian MEDIVAC helicopter crews and the Pump Station 6 ground control

personnel and to recommend a solution. This Engineering Study/Services Request

also is contained in Handout 5.

After the problem was studied, a solution was suggested. The suggestion was to install

a new radio at Pump Station 6 that would allow the ground control personnel to

communicate with the helicopter crews.

8/11/2019 CTR20104.pdf

10/103




PREPARING AN EWP FOR DESIGN OF A TRANSMISSION PATH FOR A

NARROWBAND RADIO SYSTEM

The following topics that pertain to the preparation of an EWP for the design of narrowbandradio system transmission path are covered in this section:

Specific Purpose

Required Baseline Data and Information

Required Analyses and Calculations

Appropriate EWP Formats and Content

Specific Purpose

As discussed previously, Handout 1 is a sample EWP that requires the design of atransmission path. The coverage for the paging system was unsatisfactory in the Ain Dar

area. Pagers in this area received paging signals that were near the minimum acceptable

level. These signals were the signals that were transmitted from the Abqaiq paging

transmitter and the Shedgum paging transmitter. The solution for this problem was to provide

the Abqaiq paging transmitter with its own exclusive, high gain, transmit antenna.

The determination of this solution required that a transmission path between Abqaiq and Ain

Dar be designed. The specific purpose of the Handout 1 EWP was to resolve this problem

through the design of a transmission path.


The baseline data that are required for an EWP that requires the design of a transmission path

for a narrowband radio system relates to the operational characteristics of the radio system

and to the terrain characteristics of the area around the radio system. A problem report can

contain some of the required baseline information.

The problem report will contain, at a minimum, the system name and location. Other

information that could be contained in the problem report includes the system frequency,

tower locations, performance requirements for the system, and the existing facility or system

configurations. The other information about the operational characteristics of the radiosystem equipment and terrain characteristics can be gathered from equipment data sheets or

technical manuals and topographic maps.

8/11/2019 CTR20104.pdf

11/103




Required Analyses and Calculations

The purpose of the design of a transmission path is to determine whether acceptable

communications can take place between a transmitter and a receiver. The difficulty in thedesign of narrowband radio systems transmission paths lies in the wide variety of different

types of narrowband transmission system. For example, the design of a transmission path for

an extended subscriber connection is significantly different than the design of a transmission

path for a mobile communications system.

In addition to the large variety of narrowband communications systems, many different

methods are used to design transmission paths for each of the different types of narrowband

transmission systems. Although the design of a transmission path for a point-to-point, line-of-

sight transmission path may be relatively straight forward, the design of a transmission path

for a mobile radio system is an inexact science. Much of the data that pertain to this subject

are based on empirical studies that have been conducted by Engineers in the United States,Japan, Poland, and Italy. These studies have yielded experimental data, such as the field

strength versus distance for varying antenna heights, the losses that are caused by various

structures, and the effects that are caused by transmission over various types of terrain. These

are the types of data that are used by the Communications Engineer to determine whether

communications can take place between a transmitter and a receiver.

The purpose of this Module is to explain the methods that are used to prepare EWPs. The

Module is not designed to provide an in-depth study of all of the different types of analyses

that are performed to design transmission paths for all of the different types of narrowband

radio systems. This section presents one method that can be used to design a point-to-point,

line-of-sight, transmission path. The section also describes those factors that bear on the

design of more complicated transmission paths.

The following topics that pertain to the required analyses and calculations to design a

transmission path are covered in this section:

Point-to-Point, Line-of-Sight Calculations

Computerized Spreadsheet Calculations

Factors that Affect the Design of More Complicated Transmission Paths

8/11/2019 CTR20104.pdf

12/103




Point-to-Point Line-of-Sight Calculations

This section introduces equations that can be used to design a point-point, line-of-sight

transmission path. These equations are based on the equations that are used in the computerspreadsheet that is discussed in the next section. Extended subscriber connections are

examples of point-to-point, line-of-sight narrowband communication systems. The following

topics that pertain to performance calculations are covered in this section:

Parameters that Affect the Transmission Path

Determination of Performance Acceptability

Parameters that Affect the Transmission Path -The following base station parameters that

affect the transmission path may be selected by the system designer:

The radio locations and antenna heights. The transmitter powers and frequencies.

The components that connect the transmitters to the transmit antennas.

The type of antennas that are used for the transmit antennas.

Each of these parameters interacts with the other parameters to affect the operational

characteristics of the system. The function of the performance calculations is to

determine the correct combination of these parameters that will provide the signal

level at a receiver that allows the required performance characteristics to be met.

The radio locations are the primary factor that determines the transmission path. The

location of the radios often is predetermined. Generally, the reuse of existing

facilities, such as towers and antennas, is more economical than the procurement of

new facilities. At Saudi Aramco communications sites, several systems often share the

same towers and antennas. If space is unavailable on an existing tower, a new tower

may need to be constructed; however, several other options do exist. Combiners can

be used to allow more than one transmitter to share the same transmit antenna, and

multicouplers can be used to allow receivers to share the same receive antenna. The

radio antennas also can be mounted to other existing structures, such as buildings.

The height of the transmit antenna determines the maximum distance that can be

served by the base station. Line-of-sight radio systems are limited to the distance tothe horizon. As the transmit antenna height increases, the distance to the horizon

increases.

8/11/2019 CTR20104.pdf

13/103




The remainder of the parameters determine the field strength that will be incident on a

receive antenna. As the transmitter power or the transmit antenna gain increases, the

field strength along the transmission path increases. The transmit frequency affects the

propagation loss and some other types of losses. As the frequency increases, the

propagation loss and other losses increase. Also, the components that connect the

transmitter to the transmit antenna, such as the transmission line, filters, and

multicouplers, insert some loss.

Determination of Performance Acceptability - The following methodology is used to

determine whether the performance of a transmission path is acceptable:

The minimum required received signal level is determined.

The time and location requirements are determined.

The path loss is calculated.

The minimum required received signal level is a function of the receiver sensitivity,

the receive antenna gain, and any additional losses that may be inserted by the receive

antenna subsystem. The following equation is used to calculate the required minimum

received signal strength:

The receiver sensitivity is the minimum receive signal level that is required to meet

some specified performance reference. Two common performance references are the

20 dB Quieting sensitivity and the 12 dB SINAD sensitivity. The received signal level

for each of the performance references generally is specified for every receiver. A

typical value for the sensitivity of mobile radios is about 0.5 _V. The sensitivity is the

minimum voltage that must be developed across the receive antenna to meet the 12 dBSINAD or 20 dB Quieting criteria.

To facilitate solving the performance calculations, all values are converted to decibels.

The sensitivity is converted to the power in decibels referenced to 1 milliwatt that

corresponds to the voltage that is developed across the antenna. Power is equal to the

square of the voltage that is developed across the antenna divided by the resistance of

the antenna. This relationship and the conversion factors are used in the following

equation to convert between _V and dBm:

For example, the sensitivity in dBm that corresponds to a sensitivity of 0.5 _V is

calculated as follows:

8/11/2019 CTR20104.pdf

14/103




This receiver sensitivity equals the signal strength that is required at the input of the

receiver. The minimum required signal strength must also include the receive antenna

gain and any other gains or losses. Because the receive antenna has a gain, the

minimum required receive signal strength can be reduced. Other gains or losses are

similarly included. For example, if the receiver sensitivity is -113.01 dB, if the receive

antenna gain is 3 dB, and if the transmission line inserts a 1 dB loss, the minimum

required signal strength is calculated as follows:

The equation that is used to calculate propagation loss versus distance provides a

signal level that is exceeded 50% of the time at 50% of the locations. For many

mobile radio systems, that level of performance is unacceptable. The mobile radio

system may require that the minimum signal level be exceeded 90% of the time at

99.9% of the locations. To provide this additional level of performance, the minimum

required signal level is increased. Figure 2 is a table that provides the correction

factors that are required for various levels of performance. For example, to providethe required performance 90% of the time, 10 dB is added to the minimum required

signal level. To provide the required performance at 99.9% of the locations, 30 dB is

added to the minimum required signal level.

8/11/2019 CTR20104.pdf

15/103




Correction Factors

Figure 2

With the minimum required signal level that provides the required level of

performance determined, the allowable path loss can be calculated. The following

equation is used to calculate the allowable path loss:

The transmitted power is a function of the transmitter power, the transmit antenna

gain, and any additional losses that may be inserted by the transmit antenna subsystem.

The following equation is used to calculate the transmitted power:

For example, if the transmitter power is 50 dBm, if the transmit antenna gain is 6 dB,

and if the transmission line inserts a 2 dB loss, the transmitted power is calculated as

follows:

If the transmitted power is 54 dBm and the minimum required signal level is -75.01

dBm, the allowable path loss is calculated as follows:

The performance of the system will be acceptable as long as the actual path loss is less

than or equal to the allowable path loss. The following equation can be used to

calculate the actual path loss:

where: 120 = A conversion factor and constant

F = Frequency in MHz

D = Distance in miles

H1 = Transmit antenna height in feet

H2 = Receive antenna height in feet

8/11/2019 CTR20104.pdf

16/103




This equation compensates for the free space path loss and the obstruction losses. The

frequency and distance terms are included in the equation to account for the free space

path loss. Free space path loss was discussed in CTR 101 and CTR 102. The antenna

heights are included in the equation to account for the obstruction losses. Signals that

propagate along the surface of the earth are obstructed by the earth. The obstruction

results in a loss of signal strength. Generally, as the antenna heights increase, the

signals that are propagated between the antennas are less obstructed by the earth;

therefore, as the antenna heights increase, the path loss decreases.

For example, if the frequency is 413.95 MHz, if the height of the transmit antenna is

300 feet, if the height of the receive antenna is 5 feet, and if the distance between the

transmit antenna and the receive antenna is 3 miles, the path loss is calculated as

follows:

The maximum distance from the transmitter that provides acceptable performance isthat distance where the actual path loss equals the allowable path loss. The preceding

equation can be rearranged to solve for the distance at which the actual path loss

equals the allowable path loss as follows:

For example, if the allowable path loss is 129.01 dB, if the transmitted frequency is

413.95 MHz, if the transmit antenna height is 300 feet, and if the receive antenna

height is 5 feet, the maximum distance that provides acceptable performance is


If the receiver location is closer to the transmitter than the maximum distance that was

calculated, the performance of the system will be acceptable. Several factors must beconsidered during the performance of these calculations. If the transmit antenna does

not have an omni-directional radiation pattern, the gain of the antenna will vary with

direction from the transmitter to the receiver. In those directions that have a higher

gain, the maximum distance will increase. Conversely, in those directions that have a

smaller gain, the maximum distance will decrease.

Also, these equations only are valid when the transmit antenna and receive antenna are

within the line-of-sight. The length to the horizon (the maximum line-of-sight) in

miles is calculated through use of the following equation:

where: h = Height of the antenna in feet.

For example, if the height of the antenna is 300 feet, the length to the horizon is


8/11/2019 CTR20104.pdf

17/103




Computerized Spreadsheet Calculations

Computer programs are well suited to solve the performance calculations. Figure 3 is an

example printout of a spreadsheet that provided the equations that were used as the basis ofthe section titled "Performance Calculations." The spreadsheet was developed by a Saudi

Aramco Communications Engineer in Microsoft Excel for the MacIntosh.

To use the program, the values for various parameters are input into the computer. On the

example spreadsheet printout, the values for those parameters that are in bold-face type are

entered. For example, the antenna heights, frequency, antenna gains, and path length are

entered.

The computer solves the performance calculations. Two specific solutions are important to

the communications engineer: whether the path is a line-of-sight path and the total system

gain. The computer calculates the maximum distance for a line-of-sight path when given theheights of the transmit and the receive antennas. This distance is subtracted from the entered

path length. If the difference is negative, the path is a line-of-sight path; however, if the

difference is positive, the path is not a line-of-sight path. The spreadsheet is only valid on

paths that are line-of-sight.

The total system gain is equal to the difference between the received power level and the

receiver sensitivity. If the system gain is positive, the received power level is greater than the

receiver sensitivity. The system gain must be positive for the system to meet the design

requirements.

8/11/2019 CTR20104.pdf

18/103




8/11/2019 CTR20104.pdf

19/103




Sample Propagation Spreadsheet Printout

Figure 3

8/11/2019 CTR20104.pdf

20/103




One additional input that was not used in the performance calculations is included in

the spreadsheet: the type of building inside of which a radio is located. Because

buildings will attenuate the radio signals that pass through the building, an additional

loss component must be included. This loss is not applicable to radios in buildings

that have an outside-mounted antenna for that radio. The amount of loss is a function

of the type of building and the frequency of the signal. Figure 4 is a table that shows

the loss versus the type of building for the various frequency bands.

Propagation Loss Versus Building Type

Figure 4

Factors that Affect the Design of More Complicated Transmission Paths

As was stated in the previous section, the design of a transmission path is the determination ofwhether the parameters that are chosen for a transmitter are acceptable. The basic

performance calculations that were previously introduced are suitable only for point-to-point,

line-of-sight radio systems. Different types of studies are used for point-to-multipoint

distribution and mobile radio systems and for radio systems that have obstructed transmission

paths. The following topics that pertain to the design of a transmission path for other types of

systems are discussed in this section:

Transmission Path Design Methods for Mobile Radio Systems

Obstructed Transmission Paths

8/11/2019 CTR20104.pdf

21/103

8/11/2019 CTR20104.pdf

22/103




Obstructed Transmission Paths - A clear, unobstructed transmission path is not required

for narrowband radio systems. The diffraction and reflection of the radio waves allow

radio signals to be propagated to points that would otherwise be obstructed.

Diffraction is the redirection or redistribution of the energy in a radio wave that passes

near an obstruction. Reflection is the redirection of the energy in a radio wave that

strikes a physical boundary. Again, many different methods can be used to determine

the effects of diffraction and reflection on the operation of a narrowband radio system.

Diffraction has many different forms. The distribution of the energy in a diffracted

radio wave depends on the nature of the obstruction. The nature of the obstruction

determines the way in which the energy of the radio wave is redirected into the area

behind the obstruction. Diffraction allows the propagation of radio signals behind

elevated terrain and over the horizon.

Reflections occur off of surfaces along the transmission path. The surfaces can bestructures, features of the terrain, or vehicles. The surfaces can also be formed by

atmospheric conditions, such as temperature inversions. The result of reflections is

that a radio signal may follow many different paths from the transmitter to the

receiver. Those radio signals that have taken different paths from the transmitter to the

receiver arrive at the receiver with various phases and amplitudes. Because the radio

signals at the receiver can consist of signals that have many different phases and

amplitudes, the amplitude of the received composite signal varies in amplitude and

phase.

The amplitude and phase variations that are caused by reflections result in the rapid

fades and long term fades that are experienced by mobile radio systems. Thepropagation of radio signals along more than one transmission path is called multipath

propagation. The fading that is caused by multipath propagation is called multipath

fading. Multipath fading is a rapid type of fading. The fading that is caused by

reflections off of features of the terrain is a long-term type of fading.

The variations in signal level that are caused by fading are described by various

probability distributions. For example, a log-normal probability distribution is used to

describe the losses that are associated with long term fading, and a Rayleigh

probability distribution is used to describe the losses that are associated with multipath

fading.

Reflections are required to allow radio systems to operate in some types of

environments. In large cities that have many large buildings, many locations within

the city do not have a clear line-of-sight to the transmit antenna. Without the reception

of signals that have been reflected off of these buildings, receivers that were located in

those areas that do not have a clear line-of-sight would be unable to receive

transmitted signals.

8/11/2019 CTR20104.pdf

23/103




Appropriate EWP Formats and Contents

As previously mentioned, Handout 1 is an example EWP that requires the design of a

transmission path. A transmission path was required to be designed from a new pagingtransmitter antenna at Abqaiq Comms to the Ain Dar village. The purpose of the EWP was to

improve the paging coverage in the Ain Dar village area. This example EWP is a very simple

EWP; however, the format and content of the EWP ensures that the purpose of the EWP is

met.

The reason that the transmission path was required to be designed was that problem reports

that complained of the poor paging coverage in the Ain Dar area had been submitted. The

identified problem was that paging coverage was inadequate in the Ain Dar village. A logical

hypothesis about the nature of the problem would be that the signal level in this area was

inadequate. To verify the hypothesis, signal level tests were taken in the Ain Dar village.

These tests showed that the signal level in this area was near the threshold that is required bythe paging receivers; therefore, the hypothesis has been verified.

When the problem is isolated to an inadequate signal level, the corrective actions that are

specified must address this problem, i.e., the signal level must be increased in the Ain Dar

village. Several options are available.

A new paging transmitter could be installed near the Ain Dar village and

connected into the paging network.

The power of a paging transmitter could be increased.

The loss between a paging transmitter and its transmit antenna could be

reduced.

The gain of a transmit antenna could be improved.

Of these options, the reduction of the loss between a transmitter and its transmit antenna and

the improvement in the gain of a transmit antenna are easily implemented, effective, and cost

effective solutions.

The paging transmitter that was closest to the Ain Dar village was located at Abqaiq Comms.This transmitter was connected to an antenna that was shared by several other transmitters.

The net result of this antenna arrangement was that the loss between the paging transmitter

and the transmit antenna was approximately 10 dB. Also, the transmit antenna was mounted

on the side of the tower. This mounting arrangement obstructed the radiation pattern from the

antenna. An unused antenna was connected to the top of the Abqaiq Comms tower.

8/11/2019 CTR20104.pdf

24/103




To determine whether the paging signal level could be increased to a suitable level through a

reduction of the loss between the Abqaiq Comms paging transmitter and its transmit antenna

and/or an increase in the gain of the Abqaiq Comms paging transmit antenna, a transmission

path is designed. To decrease the loss between the Abqaiq Comms paging transmitter and

transmit antenna, the transmitter is given a new antenna that is not shared with other

transmitters. This action removes the losses that were associated with the combiners that were

used to allow the multiple transmitters to share the same antenna. To increase the gain of the

transmit antenna, the antenna that is to be used for the new antenna is a high gain, offset

pattern antenna that is to be mounted to the top of the Abqaiq Comms tower. Because the

antenna is to be mounted to the top of the tower, the tower will no longer obstruct the

radiation pattern of the antenna.

The computer spreadsheet that solves the performance calculations is well-suited for this type

of transmission path design. The following parameters are entered on the spreadsheet:

The paging transmitter power.

The antenna heights.

The path length between Abqaiq Comms and the Ain Dar village.

The paging transmitter frequency (464.300 MHz).

The transmit antenna gain and the losses that are associated with the

components between the transmitter and the transmit antenna.

The parameters that are associated with the paging receivers (receiver

sensitivity, and receive antenna gain).

The percent of time and locations that meet the required receive signal level.

Because the wearers of the paging receivers (pagers) can be inside of buildings, a building

type also is entered.

If the spreadsheet shows that the total system gain is positive, the installation of a new

transmit antenna is a valid solution to the identified problem. If the total system gain is

negative, other options must be considered. The percent of time or locations that are requiredcan be reduced. For example, a change in the percent of time and locations that are required

from 99.9% to 99% provides an additional 20 dB to the total system gain; however, this

change also provides a 10% degradation in the quality of service. When a transmission path

is designed, the desired quality of service must be balanced against the feasibility for the

provision of that quality of service.

8/11/2019 CTR20104.pdf

25/103




The EWP for the installation of the new paging transmit antenna at Abqaiq Comms does not

include the printouts of the transmission paths that were designed for this project. The

printouts would have been included in the troubleshooting documentation to show that the

proposed solution corrects the identified problem. These printouts are not required in the

EWP. The purpose of the EWP is to govern the work that corrects the identified problem.

The format that is used in this EWP is relatively simple. The EWP only includes the

installation instructions for the new antenna, the communications service request that

authorizes the installation of the new antenna, and some supporting correspondence. Because

the purpose of the EWP is to install the new Abqaiq Comms paging transmit antenna that

corrects the poor coverage problem in the Ain Dar village, the format and content of this

EWP is all that is required to ensure that the purpose of the EWP is met.

8/11/2019 CTR20104.pdf

26/103




PREPARING AN EWP FOR EQUIPMENT MODIFICATIONS AND/OR

ADDITIONS FOR A NARROWBAND RADIO SYSTEM

The following topics that pertain to the preparation of an EWP for equipment modificationsand/or additions for a narrowband radio system are covered in this section:

Specific Purpose


Options for Equipment Modifications and/or Additions


Specific Purpose

Handout 2 is a sample EWP that has the specific purpose to resolve a reported problemthrough an equipment modification and/or addition to a narrowband radio system. The

reported problem that is addressed by this EWP is that Saudi Arabian MEDIVAC aircraft that

have a need to communicate with personnel at Pump Station 6 cannot communicate with

these personnel. The EWP addresses this need through the modification and/or addition of

that equipment that is required for the Saudi Arabian MEDIVAC aircraft to communicate with

the personnel at Pump Station 6.

At the time that the problem was reported, the only aviation radio system in operation at

Pump Station 6 operated at 138.25 MHz. This system was used for communication between

Saudi Aramco aircraft in the area and the personnel at Pump Station 6. The radios that were

used by the Saudi Arabian MEDIVAC helicopters operated at 122.8 MHz. The problem wasresolved through the installation of a 122.8 MHz radio at Pump Station 6 that allows the

MEDIVAC helicopter crews to communicate with the Saudi Aramco personnel.


The baseline data that are required for an EWP that requires the design of an addition or

modification of radio system equipment relates to the operational characteristics of the radio

system, the performance requirements for the radio system, and the specific problem that is to

be addressed by the addition and/or modification. A problem report on parameters for system

configuration can contain some of the required baseline information.

8/11/2019 CTR20104.pdf

27/103




The problem report will contain, as a minimum, the system name, system location, and the

reported problem. Other information that could be contained in the problem report includes

the system frequency, tower locations, performance requirements for the system, and the

existing facility or system configurations. For example, the Communications Service Request

that reported the problem with the communications between Saudi Arabian MEDIVAC

helicopter crews and Pump State 6 ground control personnel and that is located in Handout 5

provided the following required baseline information:

The affected system - Aviation Radio System.

The location - Pump Station 6.

The reported problem - Inability to perform necessary communications.

Any other information about the operational characteristics of the radio system equipment that

is required can be gathered from equipment data sheets or technical manuals. The installation

of a new base station would require the performance of a propagation analysis.

Options for Equipment Modifications and/or Additions

The equipment that is to be modified or added to a narrowband radio system depends on the

nature of the reported problem. Generally, the equipment that is to be modified and/or added

to a narrowband radio system will fall into one of the following categories:

Base Station(s)

Multiplex Equipment

Controllers Antenna System

Bridges

Base Station(s)

If no other base station in a narrowband radio system can provide coverage in a specific area

that requires coverage, a base station may need to be added to that narrowband radio system.

For example, in the example EWP, a base station needed to be added at Pump Station 6.

Although Saudi Aramco does have several 122.8 MHz aviation radio system base stations,

none of these base stations could resolve the reported problem. The problem was two fold:the communication had to occur on a radio system that operated at 122.8 MHz, and the

communication had to occur between the Saudi Aramco personnel at Pump Station 6 and the

helicopter crew members.

8/11/2019 CTR20104.pdf

28/103




Because no other 122.8 MHz aviation radio system base stations could provide coverage in

the Pump Station 6 area, a new base station would have to be installed. Even if the

helicopters that were near Pump Station 6 were within the coverage area of another 122.8

MHz aviation radio base station, provisions would still have to be made to allow the ground

control personnel at Pump Station 6 to transmit and receive through that base station.

Restated, a remote controller and connections into a wideband network that connected Pump

Station 6 to the other base station would still have to be installed.

Modifications to base stations are not uncommon. One of the reasons that base stations are

modified is to incorporate technological updates. For example, the channel guard system was

retrofitted to a number of Saudi Aramco base stations to reduce co-channel and adjacent

channel interference. Also, many Saudi Aramco base stations were originally configured for

dc control. These base stations have been converted to tone control, which allows for more

options in the control of base stations.

The output power and operating frequency of base station transmitters can also be changed.

A change in the transmitter output power would be performed to change the base station

coverage area or minimize interference. The transmitter frequency may be changed for

frequency planning purposes.

Multiplex Equipment

Multiplex equipment is used to integrate narrowband radio system audio and control signals

into a wideband communication system signal. Multiplex equipment may need to be

installed for either of two situations: to connect a remote controller to a base station or toconnect base stations in a networked narrowband radio system. For example, in the Northern

Remote Area of the ISD Local and Division radio networks that have been examined in the

previous Modules, multiplex equipment was required to connect the audio and control signals

from the remote controller at Ras Tanura to the remote base stations. The audio and control

signals are connected to a multiplexer. The multiplexer integrates these signals into a

wideband signal that is transmitted on a microwave system. At the Comm sites that have the

remote base stations, the demultiplexer extracts the audio and control signals. Also at these

Comm sites, a multiplexer integrates the received audio signals from the base stations into a

wideband signal that is transmitted on a microwave system. The audio signals are extracted

from the wideband signal by a demultiplexer at Ras Tanura Comms and connected to the

system voter panel.

8/11/2019 CTR20104.pdf

29/103




Multiplex equipment is required to be added when the output signals from a remote

controller, other type of terminal (such as the paging terminal), or base station must be

transmitted over a distance greater than several kilometers. For the multiplex equipment to be

used, wideband transmission facilities must be in place. For example, if a new Northern

Remote Area ISD Local and Division radio system base station was to be constructed south of

Nariyah and west of Khursaniyah, the audio and control signals that are transmitted between

this new base station and Ras Tanura would have to be transmitted through a wideband

communication system. Presently, in that area, no wideband communication system is

available; therefore, to construct a base station in that area, wideband communication facilities

also would have to be provided. Additionally, multiplex equipment would have to be

provided at the new base station to allow the audio and control signals to be integrated into

and extracted from the wideband signals.

Multiplex equipment frequently is modified to stay current with transmission technology. As

Saudi Aramco completes the conversion of wideband transmission systems, the multiplexequipment has to be changed to match the transmission technology. Because different types

of wideband transmission systems require different types of multiplex equipment, a change in

the type of wideband transmission system that transfers the signals between base stations and

controllers or other base stations requires a change in the multiplex equipment that integrates

the narrowband radio system signals with the wideband transmission system.

Controllers

As discussed in CTR 201.01, controllers are use to process audio signals and to generate

control signals. Audio signals from the controller microphone (or from a telemote) aretransmitted to a base station or base stations. The audio signals from a base station are

broadcast from a controller speaker (or transmitted to a telemote). The control signals that are

generated by the controller are transmitted to a base station or base stations. These control

signals include signals that perform such functions as keying transmitters, disabling the

channel guard system, and determining whether a base station operates as a remote or as a

repeater.

A controller may need to be added to allow personnel at some fixed location to transmit from

base stations and to receive mobile radio transmissions. For example, if a new base station

was to be added in Mazalij to the ISD Tactical Fire radio network, which is a non-repeater

simplex system, a remote controller would have to be added for the new base station. Thisremote controller is require to allow the personnel who use the system to communicate with

the personnel who use the mobile radios.

If the manner in which a system is configured changes, the controllers in that system would

need to be modified. For example, if the channel guard system is added to an existing system,

the controllers in that system would have to be modified to use the channel guard system.

8/11/2019 CTR20104.pdf

30/103

8/11/2019 CTR20104.pdf

31/103




are used in simplex base station antenna systems to switch the connection to the antenna

between the transmitter and the receiver.

Changes in the configuration or operation of a base station may require modifications to

antenna system components. If the coverage area of a base station is to be modified,

modifications will be made to the antenna. These modifications could include a change in the

antenna height, a change in the antenna orientation, or a change to the radiation pattern of the

antenna. The characteristics of a filter, such as the cutoff frequencies, may be modified to

provide better isolation against interfering signals.

Bridges

In a system that uses networked base stations, bridges can be used to extract the signals that

are transferred between base stations and remote controllers. Figure 6 shows how a bridge

can be connected into a narrowband radio system. Each connection point to the bridge is

called a leg. The multiplex equipment connects the narrowband system signals to the

wideband communications systems that provide the connections between the various sites in

the narrowband system. The terminating set provides the connection between remote

controllers (configured for 2-wire operation) and the bridge. Several remote controllers may

be connected to a signal terminating set, and several terminating sets can be connected to a

single bridge. The base station transmits and receives the signals. Different combinations of

components other than the combination of components that are shown in Figure 6 may be

connected to bridges.

An input from any one of the legs becomes an output to all of the other legs. For example,the demultiplexed output from one of the multiplex equipment is coupled to the transmit input

for the base station, to the received signal input for the remote controller, and to the multiplex

input for the other multiplex equipment. This arrangement allows the output signals from any

remote controller to be transmitted from all of the network base stations and allows the signals

that are received from any base station to be heard at all of the remote controllers.

Components that are called pads are associated with bridges. A pad is a device that inserts

some predetermined loss into the signals that pass through the pad. The following functions

can be performed by pads:

To ensure that all of the signals to be transmitted are applied to the various basestations at the same level.

To ensure that all of the signals that are transmitted by the wideband

communication systems that are connected to the multiplex equipment are

applied to the multiplex equipment at the same level.

8/11/2019 CTR20104.pdf

32/103




To ensure that all of the signals from the remote controllers are applied to the

bridge at the same level.

8/11/2019 CTR20104.pdf

33/103




Bridge

Figure 6

8/11/2019 CTR20104.pdf

34/103

8/11/2019 CTR20104.pdf

35/103




Background

Scope of Work

Installation Details

Equipment Tests

Parts List

Figures

The background section reviews the genesis of the project. Basically, this section details the

reason that the project is to be implemented. The scope of work outlines the specific work

that is to be accomplished through the implementation of the EWP. These first two sections

state the purposes that are to be met by the EWP.

The installation details section describes exactly how the new components are to be installed.

The equipment tests section details the tests that are to be performed to ensure that the newly

installed equipment correctly operates. While the first two sections detail the purpose of theEWP, these two sections detail how this purpose is to be met. For example, in this sample

EWP, the purpose of the EWP is to install a 122.800 MHz radio in the administration building

at Pump Station 6. This radio is to be installed to address the problem that Saudi Arabian

MEDIVAC helicopter crews cannot communicate with ground control personnel at Pump

Station 6. Because the installation details section describes exactly how the new radio is to be

installed, and the equipment tests section ensures that the newly installed radio correctly

operates, the format of these sections ensures that the purpose of the EWP is met.

The final two sections of the EWP, parts list and figures, provide the amplifying information

that is required to perform the work that was requested in the installation details and

equipment tests sections. Because these sections assist in the installation and testing of thenew equipment, the format of these sections helps to ensure that the purpose of the EWP is

met.

8/11/2019 CTR20104.pdf

36/103




PREPARING AN EWP FOR DEVELOPMENT OR ALTERATION OF A

FREQUENCY PLAN FOR A NARROWBAND RADIO SYSTEM

The following topics that pertain to the preparation of an EWP for the development oralteration of a frequency plan for a narrowband radio system are covered in this section:

Specific Purpose


Factors that Influence Frequency Selection

Required Studies


Specific Purpose

Handout 3 is a sample intermodulation study that was performed as part of an EWP to resolve

a reported problem through the development or alteration of a frequency plan. The types of

problems that can be resolved through the development or alteration of a frequency plan

include interference problems with existing systems and the prevention of interference

problems with new systems. The sample intermodulation study was performed to address a

potential interference problem with an existing radio system.


The following baseline data are required for an EWP that requires the development oralteration of a frequency plan.

The operational characteristics of the radio system.

The operational characteristics of other radio systems that may interfere with

the subject system.

The operational characteristics of any system that may suffer from interference

that is caused by the subject system.

The locations of the transmitters and receivers for all of the potentially affectedsystems.

A problem report or parameters for system configuration can contain some of the required

baseline information. The problem report will contain, as a minimum, the system name,

system location, and the reported problem. Other information that could be contained in the

problem report includes the system frequency, tower locations, and the existing facility or

system configurations.

8/11/2019 CTR20104.pdf

37/103




Interference generally can be considered the presence of unwanted signals. Much of the

baseline data that are required to determine the source potential interference problems must be

gathered from the affected system diagrams, communication site diagrams, and

communication network diagrams. Because these diagrams show locations, transmit powers,

and transmitter and receiver locations, all of these sources provide the baseline data that assist

in the determination of whether some particular signal may be present where that signal is

unwanted.

Any other information about the operational characteristics of the radio system equipment that

is required can be gathered from equipment data sheets or technical manuals.

Factors that Influence Frequency Selection

All of the guidelines that govern the use of frequencies are designed to minimize potential

interference problems. The CCIR provides guidelines for the uses of frequencies in various

types of radio systems. These guidelines are issued to coordinate the usage of frequencies

across political boundaries. Within the guidelines issued by the CCIR, each country is

responsible for the allocation of frequencies within its borders. In Saudi Arabia, the Ministry

of Post, Telephone, and Telegraph (MOPTT) is responsible for frequency allocations.

Virtually all of the narrowband radio systems that are operated by Saudi Aramco use

frequencies that are within the following frequency bands that are reserved for use by fixed

and mobile radio systems:

150 MHz - 170 MHz

400 MHz - 470 MHz

800 Mhz - 890 MHz

One exception to these bands are the frequencies that are used by the aviation radio systems.

The frequency bands that are used by aviation radio systems also are governed by CCIR and

MOPTT recommendations. Another exception is the INMARSAT system; however, the

frequencies that are used by the INMARSAT system are reserved by the CCIR for use by this

system and are not governed by national or organizational guidelines. Restated, the

frequencies that are used by the INMARSAT system are not also used by any terrestrial

systems.

All frequencies that are to be used by Saudi Aramco must be approved by MOPTT. A

number of frequencies have already been issued by MOPTT to Saudi Aramco. Saudi Aramco

is free to use these frequencies, within the guidelines that pertain to the particular frequency

bands that contain the frequencies, without further permission by MOPTT. If suitable pre-

issued frequencies are not available, Saudi Aramco must petition MOPTT for the use of

additional frequencies. The petition to MOPTT for the use of the new frequencies must

8/11/2019 CTR20104.pdf

38/103




include the reason why the new frequencies are required, a description of the configuration

and uses of the system that is to use the frequencies, and the desired frequency band.

MOPTT determines whether suitable frequencies are available. If suitable frequencies are

available, the frequencies are issued for use to Saudi Aramco. If no suitable frequencies are

available, MOPTT may simply deny the request or MOPTT may issue frequencies in another

frequency band. The entire petition process may take a year or longer.

For frequency planning across political boundaries or between different organizations, the

primary concerns are co-channel and adjacent channel interference. Because only a limited

number of frequencies are available, the same frequencies are reused by many different radio

systems. The purpose of frequency planning is to provide a sufficient separation between the

transmitters that operate on the same frequency to prevent co-channel and adjacent channel

interference.

Frequency coordination and planning is also required to prevent intermodulation interference.

This frequency planning is primarily an intra-organizational requirement; however, if

transmitters from more than one organization are to share the same tower, inter-organizational

frequency panning is required.

Required Studies

The following studies are performed for the development or alteration of a frequency plan:

Intermodulation Studies Co-Channel Interference and Adjacent Channel Interference Studies

Intermodulation Studies

The purpose of an intermodulation study is to determine whether the transmission of a

frequency at a particular site could generate interfering intermodulation components. As was

discussed in CTR 201.02, transmitted signals and their harmonics can be coupled to the

output of other transmitters or to the inputs of receivers; these signals mix to form

intermodulation components. Depending on the frequencies that are mixed, the frequency of

the intermodulation components can be equal to the receive frequency of a receiver. Ifintermodulation components that are equal to the receive frequency of a receiver are

generated, these signals will interfere with the desired receive signals for that receiver. This

interference is referred to as intermodulation interference.

Intermodulation interference primarily is a problem at those communication sites that have

multiple transmit and receive antennas that are close together. Intermodulation studies are

performed when a new transmit or receive frequency is to be added at a communication site

or when a receiver at a communication site suffers from intermodulation interference.

8/11/2019 CTR20104.pdf

39/103




Intermodulation studies are best performed by computers that have been programmed to

perform the studies. The number of calculations that are involved in an intermodulation study

prevent the manual performance of intermodulation studies.

All of the transmit and receive frequencies for the site that is to be studied are entered into the

computer. The computer can calculate all of the different intermodulation components that

can be generated by the different combinations of transmit frequencies. Because an infinite

number of intermodulation components can be generated from the various transmit

frequencies, the study is limited to certain combinations of frequencies. Generally, only the

two-frequency third order and two-frequency fifth order intermodulation components are

calculated. The intermodulation study may also calculate three-frequency intermodulation

components and seventh order intermodulation components.

After all of the desired intermodulation components are calculated, the frequency of theintermodulation components are compared to the frequencies of the receivers at the

communication site. The computer then supplies a listing of those intermodulation

components that are close to or equal to the frequencies at which the receivers operate.

The communication engineer then analyzes the listing to determine whether a potential

intermodulation interference problem exists. At those communication sites that have many

transmitters and receivers, potentially interfering intermodulation components probably will

be generated; therefore, the engineer will be required to determine the potential consequences

of the interfering intermodulation components. For example, if one of the signals that

generates an interfering intermodulation component is from a seldom used or back-up

transmitter, or if the transmit antennas of the transmitters that transmit the interfering signalsare widely separated, the potential consequences of the intermodulation interference is

minimal.

One transmit frequency may contribute to the generation of many interfering intermodulation

components. If this situation occurs, that transmit frequency should not be used at that site.

The intermodulation study whose results are included in Handout 3 was performed to

determine the potential intermodulation interference at the Ras Tanura communication site.

This intermodulation study determined all of the potentially interfering two-signal third order

intermodulation components that could be generated at the Ras Tanura communication site.

This communication site has 58 separate transit frequencies (proposed) and 59 separatereceive frequencies (proposed). A number of proposed frequencies were added to determine

what intermodulation products might be expected. The list, therefore, is considerably larger

than is actually the case presently at Ras Tanura.

The results of the intermodulation study show that the output signal of transmitter 55 can

combine with the output signal of the other transmitters to generate intermodulation

components that interfere with 22 different receivers. Restated, transmitter 55 contributes to

8/11/2019 CTR20104.pdf

40/103




the generation of intermodulation components that are within 0.02 MHz of the input

frequency of 22 different receivers. The results of this study would confirm the source of

intermodulation interference that could be experienced by the receivers at this communication

site. As a consequence of the results of this interference study, the communications engineers

may determine that the transmit frequency of transmitter 55 should be changed.

8/11/2019 CTR20104.pdf

41/103




Co-Channel Interference and Adjacent Channel Interference Studies

The purpose of co-channel and adjacent channel interference studies is to determine whether

the signals that are transmitted from a particular transmitter will interfere with the operation ofreceivers that are tuned to approximately the same frequency. The performance of co-channel

and adjacent channel interference studies is not as straightforward as the performance of

intermodulation interference studies.

When a narrowband radio system is first designed, the transmitted frequencies are selected so

that the transmitted frequencies are sufficiently separated from the receive frequencies of the

receivers that are associated with the other radio systems that are located in the same area.

Generally, the operating frequencies of different narrowband radio systems in the same area

should be separated by more than 0.02 MHz, and the frequencies are normally separated by

0.05 MHz. This amount of separation is sufficient to prevent co-channel and adjacent

channel interference.

Co-channel and adjacent channel interference can occur within one radio system. This type

of situation was defined in a previous Module as coverage overlap. Coverage overlap is a

potential problem in any wide area narrowband radio system.

Every transmitted signal can potentially be the source of co-channel or adjacent channel

interference. The primary factors that determine whether this potential is realized are the

distance between the systems that operate at the same or approximately the same frequency,

the transmit power of the transmitters that are associated with these systems, the height of the

antennas that are associated with these systems, and the gains of these antennas. A co-

channel and adjacent channel interference study determines whether the values of these

factors are such that interference will occur.

The first step in the determination of whether co-channel or adjacent channel interference

occurs is the solution of the performance calculations. If the transmission path between the

components of two systems that operate at approximately the same frequency is a line-of-

sight path, the spreadsheet that was discussed in the section titled Performance Calculations in

this Module can solve the basic performance calculations. Basically, the interfering signal

level between the components of the two systems is calculated. If the propagation loss is such

that the interfering signal level is greater than the sensitivity of a receiver, interference will

occur. Generally, if a line-of-site path exists between the components of the two systems,interference may occur. Even if the transmission path is not a line-of-site path, diffraction

may allow for a transmission path between the two systems. If interference due to diffraction

is suspected, propagation losses that are associated with the interfering systems should be

calculated.

8/11/2019 CTR20104.pdf

42/103




Anomalous propagation conditions may provide a higher received signal level than would be

expected based on the performance calculations. Temperature inversions and atmospheric

ducts are examples of anomalous propagation conditions. A temperature inversion provides a

reflective boundary in the atmosphere. The reflective boundary is formed at the interface

between air masses of different temperatures. As radio signals propagate, the signals

alternately reflect off of the reflective boundary and the surface of the earth. As a result of

these reflections, signals can be propagated over great distances that extend over the horizon.

A duct is an area in the atmosphere that has two reflective surfaces. Radio signals can

become trapped in the duct and propagate over tremendous distances. The gulf region of

Saudi Arabia is particularly susceptible to the formation of both temperature inversions and

atmospheric ducts.

While the potential for anomalous propagation must be considered in the design of radio

systems, the actual effects of an anomalous propagation condition cannot be predicted. In a

location that experiences anomalous propagation, such as Saudi Arabia, an extra margin ofdistance can be added between systems that operate at approximately the same frequency to

help minimize the effects of anomalous propagation. Even this will seldom achieve

interference-free communications in the gulf region.


The format and content of an EWP for the development or alteration of a frequency plan for a

narrowband radio system are designed to ensure that the frequency plan that is developed or

altered does not cause intermodulation, co-channel, or adjacent channel interference. The

EWP should provide the background for the development or alteration of the frequency plan.The EWP also will specify those studies that should be performed and the criteria that are to

be used to judge the results of the studies.

8/11/2019 CTR20104.pdf

43/103




WORK AID 1: RESOURCES USED TO PREPARE AN EWP FOR DESIGN OF A

TRANSMISSION PATH FOR A NARROWBAND RADIO SYSTEM

Work Aid 1A:Problem Report

Figure 7 is an Engineering Study/Services Request, and Figure 8 is a Communications

Service Request. These figures should be used as directed in Exercise 1.

8/11/2019 CTR20104.pdf

44/103




8/11/2019 CTR20104.pdf

45/103




Engineering Study/Services Request

Figure 7

8/11/2019 CTR20104.pdf

46/103




8/11/2019 CTR20104.pdf

47/103




Communications Service Request

Figure 8

8/11/2019 CTR20104.pdf

48/103




Work Aid 1B:EWP for Design of a Transmission Path

EWP TO INSTALL EXTENDED SUBSCRIBER CONNECTION

Table of Contents

1. Background

1.1 Rig ADC-1 Ain Dar Gosp 2 requires telephone service.

1.2 No existing telephone facilities are located near the new facility.

2. Scope of Work

Telephone service will be provided by an extended subscriber connection between AinDar Gosp 2 and Rig ADC-1. To accomplish this objective, extended subscriber radio

equipment will be installed in Ain Dar Gosp 2 and the rig. The required equipment

properties are to be determined based on the results of a transmission path that is

designed between the extended subscriber radios and the allocated frequencies of

406.125 MHz and 411.125 MHz. Telephone connections are to be performed by the

telephone technicians.

3. Installation Details

All work associated with these instructions will be done in Ain Dar Gosp 2 and Rig

ADC-1.

3.1 Design a transmission path between Ain Dar Gosp 2 and Rig ADC-1.

3.2 Mount a directional antenna (Item 1, Section 4) on the tower at Ain Dar Gosp

2. Position the antenna at the height that was determined by the transmission

path design. Orient the antenna toward Rig ADC-1.

3.3 Install an extended subscriber radio (Item 2, Section 4) in Ain Dar Gosp 2

Communications Room, as shown in Figure 9.

3.4 Install an extended subscriber radio(Item 2, Section 4) in Rig ADC-1, as shown

in Figure 10.

3.5 Install and terminate interconnecting coaxial transmission lines (Item 3, section

4) between the transmitter and the transmit antenna and the receiver and

receive antenna at the Ain Dar Gosp 2 Communications building.

8/11/2019 CTR20104.pdf

49/103




3.6 Install and terminate interconnecting coaxial transmission lines (Item 3, Section

4) between the transmitter and the transmit antenna and the receiver and the

receive antenna at Rig ADC-1.

4 Parts List

ITEM QTY DESCRIPTION

1 2 Directional Antenna, DB-252, or equivalent, 10 dB gain.

2 2 Extended Subscriber radio ACME 469 or equivalent

3 100 LDF4-50, Coaxial transmission Line

4 As Reqd Pipe mounting Hardware

5 As reqd Miscellaneous mounting hardware

5. Figures

1. Ain Dar Gosp 2 Communications Building

2. Rig ADC-1

8/11/2019 CTR20104.pdf

50/103




Ain Dar Gosp 2 Communications Building

Figure 9

8/11/2019 CTR20104.pdf

51/103




New Facility

Figure 10

8/11/2019 CTR20104.pdf

52/103




Work Aid 1C:Pertinent Data Concerning Transmission Path and System Equipment

Figure 11 is a printout of the computerized spreadsheet that is used for the transmission path

design.

8/11/2019 CTR20104.pdf

53/103




Transmission Path Spreadsheet Printout

Figure 11

8/11/2019 CTR20104.pdf

54/103




Work Aid 1D:Procedures

1.0 Determine the specific purpose that is to be addressed by the EWP.

1.1 Use available Communications Service Requests, Engineering Study/Services

Requests, or other sources of baseline data to determine the problem.

1.2 Ensure that the purpose of the EWP is to address the identified problem.

2.0 Design the transmission path for the system that is to be installed or modified in

response to the EWP.

2.1 Use the computer spreadsheet, terrain data, and the equipment specifications to

design the area-to-area transmission path.

2.2 Construct terrain profiles.

2.3 Determine antenna heights for clear line-of-sight.

2.4 Use Saudi Aramco spreadsheet, Figure 11, and any other applicable Saudi

Aramco design procedures to determine path performance.

2.5 Select components that provide acceptable path performance.

3.0 Provide for the installation or modification of the system components as required to

accomplish the purpose of the EWP.

4.0 Provide the means to test the actual performance of the transmission path.

8/11/2019 CTR20104.pdf

55/103




WORK AID 2: RESOURCES USED TO PREPARE AN EWP FOR EQUIPMENT

MODIFICATIONS AND/OR ADDITIONS FOR A NARROWBAND

RADIO SYSTEM

Work Aid 2A:Problem Report

Figure 12 is an Engineering Study/Services Request, and Figure 13 is a Communications

Service Request. These figures should be used as directed in Exercise 2.

8/11/2019 CTR20104.pdf

56/103




Engineering Study/Services RequestFigure 12

8/11/2019 CTR20104.pdf

57/103




Communications Service Request

Figure 13

8/11/2019 CTR20104.pdf

58/103




Work Aid 2B:Pertinent Equipment Specifications

The paging system consists of a number of base stations that are connected to a terminal that

is located in Dhahran. To add a base station, the following factors that pertain to the basestation equipment must be considered:

The audio and control signals that are to be transmitted by a base station are

outputs from a demultiplexer.

Omni-directional antennas are used for the existing paging base stations. The

antennas are placed as high as possible.

With the exception of the antenna, all base station equipment is to be housed in

a suitable enclosure. The enclosure must be equipped to meet the electrical

power requirements of the base station components.

A standard paging base station that has been removed from Haradh Comms is

to be installed at Damman R&D Building.

The following equipment data sheets (Figures 14 through 28) describe

equipment that is available for use for the antenna system to be installed at

Damman R&D Building.

8/11/2019 CTR20104.pdf

59/103




Antennas

Figure 14

8/11/2019 CTR20104.pdf

60/103

Engineering Encyclopedi

CTR20104.pdf

Documents

Transcript of CTR20104.pdf