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SLOPE STABILITY 48 E&MJ; • OCTOBER 2017 www.e-mj.com Every second and pixel count when it comes to detecting and acting on slope failures. When in the market for solutions, speed of results may be the foremost con- sideration behind accuracy. Many of the suppliers pitch their products as provid- ing both. In reality, some of the more re- cent solution releases do represent note- worthy breakthroughs in these areas. A few examples illustrate that point. Reduced Ambiguity, Increased Versatility In June, IDS GeoRadar released the IBIS- ArcSAR, a synthetic aperture radar (SAR) touted as a world's first. The literature pegs it as "the first and only radar in the min- ing industry to provide 360° pit coverage capabilities" by a single unit. "The system leverages the widest and longest range (5,000 meters [m]), and the shortest scan time (360° in 40 seconds, 180° in 20 seconds) as well as built-in global naviga- tional satellite system" (GNSS) function- ality for auto-geocoding, IDS GeoRadar re- ported. It features 10-million-pixel spatial resolution and an integrated panoramic high-definition camera for real-time imag- ery of pit walls and critical areas. While those features distinguish the ArcSAR, it is the scan speed that tru- ly sets it apart, Cliff Preston, business development manager, IDS, said. "Typ- ically with radar monitoring, scan times started out, for real aperture radars, any- where from eight minutes to 30 minutes depending on how big of an area they were scanning," he said. The IBIS FM, predecessor technology to the ArcSAR, dropped that down from two to four min- utes, Preston said. "The ArcSAR is scan- ning a full 360° in 40 seconds," he said. "You've increased more than tenfold the maximum measurable velocity." That means, because the amount of possible movement between each scan is reduced due to the scans occurring in quicker succession, there is less "phase ambiguity," or essentially guesstimates of the true extent of any movement, Preston said. A typical real aperture radar "can measure a quarter of an inch between each scan," he said. If the movement between scans exceeds a quarter of an inch, it is dif- ficult to gauge the exact amount. With the ArcSAR, the faster scan time and therefore higher frequency of scans means "a fast- er velocity of displacement that you can measure," he said. "We can see closer and closer what is happening during a failure." Heightened scan speed also enables the ArcSAR to do double duty, which is ex- actly what the company sought back when it originally hit the drawing board. "This arose because we saw two different ways radars were used in the market," Preston said, referring to what he called tactical and strategic use. The former is for mon- itoring "an area they know is moving," he said. The latter is for watching a "a much larger area of the mine because you don't know what else is moving out there so you want to measure all parts of the pit." ArcSAR "allows them to use it both ways," Preston said. "If you are a mine site and you are budgeting to buy a radar and you don't know if you want a long-range solu- tion that is semipermanent, like the IBIS FM, or if you want a shorter range tacti- cal unit, which usually takes more of the engineers' and technicians' time because they have to move it around more, now you have a unit that can do both." ArcSAR is unique due to the path along which the signal is transmitted. Typ- ically, a SAR transmits along a linear path, a straight path back and forth. That simu- lates a larger antenna. "What is different about the ArcSAR is that it is moving the antennae in an arc path, and what this al- lows us to do is to have less moving parts in the system and a higher reliability by the mechanical properties of it," Preston said. "The other thing it allows us to do is scan in a much wider coverage area." Preston describes the arc path as a major breakthrough. "We had to change the way that the data is focused and pro- cessed a little bit," he said. "This is pret- ty significant in that it is the only radar out there right now that does this." The benefits are many, he said. First, there is the reliability. "You only have to ro- tate around one center point now instead of moving a rail back and forth and rotating a rail," Preston said. Then there is the higher resolution and longer coverage. "It increas- es the capabilities of the radar across the board doing it this way," he added. The radar employs a MIMO (multiple input, multiple output) antenna array to Slope Stability Solutions Give Actionable Data Fast New and established products compete at accuracy, speed and usability By Jesse Morton, Technical Writer Standard with the IBIS-ArcSAR is the upgraded IBIS-Guardian software. Large sites can upgrade to the FPM360 suite, which can synthesize data from multiple radars. Above, a Guardian screenshot. (Photo: IDS Engineering)