Editorial

Drive Test in Desert Areas

Our Experience in Field Measurements for Oil and Gas Companies

“Conducting field measurements in extreme conditions is not an easy job” says Mr. Dimitris Antonopoulos, Net Technologies field engineer, referring to his experiences with Oil and Gas companies in the Gulf. For the planning and implementation of a communication network, the site survey and site inspection is one of the major tasks and prerequisite for successful project completion. The site survey results are used by a team of radio network planners and project management as the basis for the network design as well as for the procurement of the network equipment. Field measurements, which are part of the site survey in a wireless communication system, are therefore crucial.

Net Technologies has gained vast experience in field measurements over the years. Recently the company has successfully implemented a series of field measurements for TETRA networks, planned and implemented for an Oil and Gas company in the Gulf area. Field measurements were performed at desert areas, offshore oil platforms, in complex oil and gas facilities, as well as in underground sites and tunnels. The successful completion of these measurements was a unique and challenging task.

The measurement equipment used for the investigation of possible interference sources was a portable spectrum analyzer, a protocol analyzer and logging software, a GPS receiver and an external directional and/or omnidirectional antenna.

The measurements were conducted in a very challenging environment with temperatures reaching 50C in addition to excessive humidity, sandstorms, 8 to 10 hour drives crossing the desert and flying by helicopters to the off shore areas (oil rigs).

The scope was to measure the frequency and signal strength of various existing signal sources, and take it into account for the frequency allocation of the new network. By the employment of the logging software, the measurements were stored and processed and the measurement outcomes where considered during the frequency assignment procedure, assisting the provision of an interference free frequency plan.

Underground sites are complex facilities that consist of tunnels and cavern areas which extend in different levels under the ground. At these sites the solution for communications consists of distributed antenna systems including leaky feeder cables, amplifiers, antennas etc.

We have undertaken the task to verify the sufficiency of radio coverage in all of the areas where existing Leaky Feeder Cable (LFC) was installed, indicating the condition of the existing LFC, as well as to confirm the operation of the LFC according to the specifications in terms of longitudinal and coupling loss. The measurement results were compared to the theoretical calculated values and then taken into account in the design for a new network.

The first step towards the measurement campaign conducted at the underground sites consisted of the inspection of the LFCs along their whole route starting from the base station, checking of the antenna types and locations and inspection of the physical environment. The second and most important step was to conduct a series of measurements using the existing radio communication system.

The existing radio equipment was evaluated with the use of a spectrum analyzer that measured the output power of the existing base stations and one RF receiver that measured the signal strength along the radiating LFC and antenna system, with all other systems being operational and noise sources being present.

The design of the new underground communication network was based on these field measurements, in terms of evaluating the conformance of the existing radio equipment (antennas, leaky feeder cable, amplifiers, splitters etc.), resulting in a comprehensive, efficient, and cost-effective design.

For a successful site survey, the radio field measurements, interference measurements as well as signal strength measurements and the evaluation of existing radio equipment infrastructures, such as distributed antenna systems including leaky feeder cables are essential. It is also very important for the site survey teams to be familiar with the environmental conditions (high temperatures), the terrain morphology (desert areas) and the complexity of facilities (underground facilities, tunnels and offshore platforms). It saves time, cost, and unscheduled design modifications during the implementation phase of the project.

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