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Cartography

More accurate maps

New radar provides more exact topographical data

eduardo cesarAntenna of the Saber M-60 system identified aircraft at a 60-quilometer radiuseduardo cesar

The three partners of Orbisat, a firm specialized in remote sensing and headquartered in the city of São José dos Campos, in inner-state São Paulo, have good reasons to celebrate. Their sales this year are expected to reach R$60 million, or 40% more than in 2007, when they amounted to R$43 million. The reason behind such substantial growth is the firm’s ongoing investment in technological innovation. The company’s most recent innovation, which took one year of research and a R$500 thousand investment, is an advanced version of the aircraft-carried radar OrbiSar RFP (radar for penetration of vegetable cover), for the production of three dimensional maps  to improve the accuracy of the real topography of soil in the forests, captured from 1.5 meters to just one meter. In addition,  the firm’s engineers and technicians are developing, in conjunction with the Brazilian army, a number of aerial surveillance radars, that were named Saber (Sistema de Acompanhamento de Alvos Aéreos Baseados em Emissão de Radiofreqüência, i.e., a system for monitoring aerial targets based on radiofrequency emissions) and are working on a modification of the OrbiSar RFP to detect oil spills on the sea’s surface.

The accuracy of the new OrbiSar RFP version is one of the best in the world. “We managed to capture images with altimetrical precision of at least one meter”, says João Roberto Moreira Neto, an electronic engineer and an Orbisat partner and director. Providing accurate information about terrain topography is vital for firms in the mining industry and in the electrical sector, among others. Mining companies must be very familiar with the soil on which their mines are located, in order to calculate the amount of soil that must be removed to reach the subterranean mineral layer. Builders of large hydroelectric power plants must know the details of the terrain in which the power plant’s reservoir is to be built, in order to work out the area to be flooded. The data collected by the cartographical radars OrbiSar RFP also provide information about the type of soil covering, biomass distribution and the water runoff in the pictured region.

OrbiSar RFP relies on the InSAR technology (Interferometric synthetic aperture radar), which takes advanced pictures of the soil, showing the dimension of trees, rivers, roads and buildings. The Orbisat model was designed to generate precise geographical information, especially in areas with thick forests, and it employs two mapping frequencies simultaneously: bands X and P. “Band P penetrates the forest and measures ground height with precision of one meter”, explains Moreira Neto. “Band X measures the height of the tree tops”. The secret behind increasing the precision level was the development of more accurate data processing algorithms.

The radar also produces images at night or on overcast, stormy days. Instead of using light to do the mapping, like conventional systems, the RFP emits electromagnetic waves. “We obtain the data faster, more precisely and more cheaply, because our radar doesn’t depend on atmospheric conditions or on daylight. We can map large areas in a minimum amount of time, using a small plane for only a short time”, explains Moreira Neto. The market price of this radar is as much as R$8 million. It is carried by aircraft and emits electromagnetic waves, pulsed during the course of the trip; it gets the return signal through its antennae. Being 1.2 meters wide, 1 meter high, 60 centimeters long and weighing 200 kilograms, the radar stays within the aircraft, whereas the aerials for band P are placed in the luggage compartment and for band X outside the aircraft. Data processing is automatic. “We developed the software and continue to update it on an ongoing basis”, says Moreira Neto. Orbisat sells not only the radar but also mapping services. The company has conducted sensory work in Venezuela, Ecuador, Switzerland, Italy and England.

Orbisat Outside the aircraft, antennae emit electromagnetic waves and capture signals from the soilOrbisat

By sea and by air
The new OrbiSar RFP version can also detect oil spills on the sea. In this case, the research work was financed by FAPESP through its PIPE (Innovative Research in Small Firms) program. The antenna project is in its final stages and is being conducted at FEEC, the School of Engineering and Computing at the State University of Campinas (Unicamp). “We expect to conduct the first flight this year. Our target is to start to providing services to Petrobras as of 2009”, says Orbisat’s partner-director, who has a letter of intent signed with the oil company. “With a new antenna in band X and real time processing, it will be possible to locate the oil spills that are as far as 100 kilometers away from the aircraft. We can conduct a full search of the Campos basin, whose area covers 90 thousand square kilometers, in under four hours”, says Moreira Neto. This system captures the movement of  waves. The electromagnetic frequencies sent by  radar are reflected back by the small waves that the wind forms. When there is oil on the surface of the sea, the superficial tension rises, causing the little waves to disappear, so that the antenna do not read them when the emissions return.

The development of the line of Saber aerial surveillance radars also enjoys Unicamp’s support. FEEC researchers are responsible for the antenna project of the Saber M-60 model, capable of identifying aircraft within a 60 kilometer radius or of identifying those who fly as much as 5 thousand meters above it. After this height, detection becomes the responsibility of the air traffic radars of the Aeronautics Ministry. “During the research and development stage, two prototypes were produced and now, in the industrialization stage, another three are being made and delivered to the Brazilian army within the next few months”, says lieutenant-colonel Roberto Castelo Branco Jorge, the army’s M-60 radar project manager. The market price of radars is estimated at R$3 million.

A software program developed jointly by Orbisat, Unicamp and CTEx, the Army’s Technological Center, enables the radar to track and to supply, in real time, the precise location of as many as 40 air targets simultaneously. A company that is 100% Brazilian, Orbisat, which was created in 1983, develops projects in the fields of electronic engineering, automatic test systems for electronic cards, industrial automation and control, and radionavigation equipment. It allows Brazil to belong to the select group of countries that have radar production technology, a group that also comprises the United States, Canada, Germany, the Netherlands and France. The company’s growth over the last few years was good; it now boasts 270 employees, far more than its headcount of 100 in 2003, when Orbisat was the subject of an article in Pesquisa FAPESP, issue no. 83, dated July 2003.

The Project
Processor for the detection of oil spills (nº 03/13180-5); Modality PIPE – Innovative Research Program for Small and Very Small Companies; Coordinator João Roberto Moreira Neto – Orbisat; Investment R$ 318,400.00 (FAPESP)