FCC compliance and frequency selection for SCADA
Radio-frequency solutions remain viable for off-shore installations.
SCADA systems, also sometimes referred to as multiple address systems (MAS), are heavily governed by the rules and regulations of the Federal Communications Commission (FCC), and in some situations, the Federal Aviation Administration (FAA).
In the oil & gas industry, SCADA systems are relied upon to enable controlling valves, monitoring flows and collecting data. Systems of this nature are used widely from offshore platforms in the Gulf of Mexico and throughout the United States to aid in safe, efficient operations and environmentally responsible production and transmission of petroleum, electric or utility products. The systems poll and control numerous sites on a periodic basis to provide management with reliable and current data with respect to important operating parameters, including: valve settings, flow rates, volume and pressure differentials.
Over the years, SCADA technology has advanced through the addition of Internet protocols, an increase of modulation rates, and most recently, use of cloud modalities for data storage and management.
Initially, devices installed at control and data collection points, called remote terminal units (RTU), used simple dual-tone multi-frequency (DTMF) techniques, following telephone companies that started using touch-tone for dialing and internode signaling rather than DC pulses. The next generation of RTUs adopted RS-232 data exchange, as transmission facilities moved from DTMF analog to digital.
"When the Internet became increasingly used for all manner of information and communication exchange, demand grew for even newer methods for handling data and control; thus, Internet-protocol interface for devices and systems came into favor," said Darryl Parker of Alligator Communications.
While the technology environment evolved, the basic function did not change for SCADA systems. There was still the fundamental requirement to control devices and gather data about operations. The reality was now use of a leased common carrier, or in other words, the telephone company. Due to the cost of expanding services, facilities were scarce or unavailable in many remote locations, as was the Internet.
A radio-frequency (RF) solution solves many of these challenges because it does not rely upon heavy capital expenditures for construction, is easier to maintain, more reliable and its implementation may not involve as much bureaucratic delay.
RF equipment options are available and buying radios can be easy. It is often the other components involved which can lead to confusion. Keeping a few things in mind will help.
For example, are the radio units licensed under the FCC rules requiring a radio authorization? If so, will the radios fall under Part 90, land mobile operations; Part 101, for MAS operations; or the unlicensed 902-928 MHz band? Bear in mind that the unlicensed operations are not included in the FCC’s database and operations among users are at-will and subject to interference. Another question to ask is whether any transmit antenna will be located on a structure requiring registration with the FAA and possibly the FCC?
Before purchasing equipment, it is important to know if spectrum for it is available. In certain blocks in the Gulf of Mexico, like Garden Banks and Vermillion, 900 MHz MAS systems may not be an option due to congestion or because of the required 90-mile separation between transmitters. Finally, unlike with operations on land, out at sea "real estate" is not as available and users are limited to transmitting from a platform.
"In our practice, we have found that due to the uptick in oil field activity, Part-101 MAS spectrum can be scarce, so we urge our clients to be open to Part-90 frequencies, and we also suggest they not hold off on deciding, so we can secure a frequency as quickly as possible," said Mona Lee, president, Mona Lee & Associates, LLC.
Pros and cons apply to both Part-90 SCADA and Part-101 MAS operations. The chart that accompanies this article, specifies considerations that should be taken before purchasing radio equipment.
"Finding a licensed Part-101 frequency is usually fairly easy, if you aren’t in a congested area, but short spacing can still be a viable alternative. There are several options available when trying to find a frequency. Rarely does it happen that some solution can’t be found," said Jeremy Lewis of Micronet Communications, Inc.
In summary, know what spectrum is available in the desired vicinity for usage before purchasing equipment. Engineers and managers first should determine whether Part-90 SCADA, Part-101 MAS or unlicensed 902-928 MHz operations will best meet the needs for secure operations. This can avoid what could otherwise become a costly matter.
Elizabeth Buckley is an FCC radio licensing expert with FCC-FFA Licensing, LLC, in Alexandria, Va. She has been handling FCC and FAA applications for oil, gas and utility companies for over 27 years. Buckley is a participant on the ENTELEC Regulatory Committee and Utilisite Joint Use Committee.
For more information: www.fcc-faalicensing.com/