Trends & Insights from an Industry Pioneer
About Subsurface Reflections:
The goal of this blog is to share interesting and inspiring articles related to subsurface imaging and geophysics. Written by experts in the field of geophysics, ground penetrating radar, software development and data analysis, this is a source for insights about the practical application of technology in the field of subsurface imaging and a place to shed light on common misconceptions in the industry.
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Ground Penetrating Radar (GPR)
Dr. Peter Annan
Founder & CEO
Peter is the CEO of Sensors & Software. His scientific research has been recognized worldwide with numerous awards for his pioneering work in ground penetrating radar (GPR) instruments and data analysis methods. He has authored multiple scientific publications, patents, and technical reports and served on various government and professional committees.
GPR is one of the few geophysical technologies that is subject to heavy regulation. We are fortunate even to be able to have GPR systems to use at this time. Given the starting point and the weight of objection that first appeared about 20 years ago, we are indeed fortunate. The challenge of regulation was stimulated by a degree of stupidity in the GPR user community and by the advent of the idea of using short pulse encoded data for information transmission. The use of pulse encoded signals and related ideas were referred to as ultra-wideband (UWB) signals. At the time, the only real commercial devices that fit in this description were – surprise, surprise – GPR’s.
Since that time, I have been heavily engaged, along with a few other hardy souls, in the battle to preserve the right to use GPR technology. Throughout this period, it has been fascinating and educational to both understand the driving forces and to become adept at maneuvering through the halls of regulatory hell to get acceptable regulations in place.
Regulation is one of most unproductive areas to spend time and has driven me to distraction many a time. Countless hours of my life have been gobbled up by dealing with the bureaucracy, reading obtusely worded documents, translating narrow band jargon in UWB understanding, writing formal briefs, developing the patience to accept the slow rule-making pace and accept that science is not the basis for most decisions!
While my preceding comments vent frustration, the GPR community should inform themselves as to why regulation has occurred and why it must be considered as an important issue.
To be straight-forward and factual, GPR’s produce electromagnetic signals in the radio wave frequency spectrum range which, in principle, could interfere with other devices using the radio wave spectrum. The probability of GPR creating interference is low but cannot be ignored by wishful thinking.
Getting to the point, the GPR community must recognize that governments around the world have agreed for decades on how to coordinate and manage the use of the radio wave spectrum with the coordinating body being the International Telecommunications Union (ITU). Surprisingly, my awareness of the ITU only surfaced after about 5 years in the regulatory battle. The primary regulators are spectrum manager agencies in individual countries, not the ITU. For example, the Federal Communications Commission (FCC) in the USA regulates the public spectrum use. A separate agency, the National Telecommunication and Information Administration (NTIA), manages the USA government use of the spectrum. In Canada, Industry Canada (IC) manages the spectrum. The ITU is the overarching entity that all the spectrum management agencies work through to coordinate their activities. Confusing to the uninitiated for sure!!
Why all this need for agencies and coordination? Just imagine two radio or TV stations operating at the same frequency in cities on opposite sides of a border. Chaos could ensue.
Further, the spectrum is a valuable commodity and governments license the use of this commodity. The spectrum is segmented into narrow frequency slices (or bands) typically of a few kHz or MHz in width between 100 kHz and 100 GHz. The right to use these frequency slices are sold to users for substantial amounts of money. A typical TV channel in bygone days would span a 6 MHz slice of spectrum. You may occasionally hear about billion-dollar auctions of cell phone frequency bands. Hence, spectrum is something that governments can sell for money and they do it regularly.
Once a frequency range has been defined and licensed out, no one else can use that frequency band in a defined geographic area. The buyer is the sole owner of that piece of spectrum.
As stated early, GPR is a UWB device which means it uses a wide swath of frequency spectrum. The reason GPRs are ultra-wideband is the need to resolve small scale information in the ground. GPRs have spectrum spans of 100’s and even 1000’s of MHz which makes the TV example of normal use seem small. As a result, GPR devices will span many normal uses of the spectrum such as:
- Shortwave radio
- Broadcast TV
- Navigation bands
- Cell phone bands
- Satellite bands
- GPS bands
- And many more
In order to get governments around the world to allow the use of GPR in these valuable frequency bands, the GPR community had to show that GPR devices would function at or below the noise floor that all these other uses of spectrum declare. As a result, this requires a great deal of effort on the part of the GPR designers and manufacturers to make GPR devices that will function effectively, while meeting stringent limits on output signal power.
One of the interesting discussions that occurred early in the evaluation of GPR for regulation puts part of the struggle into perspective. Regulators place emphasis on the distinction between intentional and unintentional radiators. What does this mean? The electrical currents in an electric drill motor will generate some radio wave signals. These signals are a by-product of its operation but play no part in its use to a drill hole and hence are unintentional. On the other hand, a radio transmitter sending music and news information to a receiver must use radio wave signals to carry the information; the transmitter cannot perform its intended function without emitting radio wave signals and hence it is an intentional radiator.
The GPR community claimed that the GPR was an unintentional radiator because the radio waves are only needed to look into the ground and that any signals going elsewhere were unintentional. The regulators pushed back strongly saying GPR was an intentional radiator since it needed to create radio wave signals to work. End of story!!!
The GPR community, by being persistent and making regular input to the regulating agencies, was able to ameliorate some of the more draconian outcomes that might have occurred, such as the outright banning of GPR. The resulting regulations are, by no means, perfect but at least they are manageable and the GPR community can continue to exist and advance many useful applications.
The GPR community has been operating in the world of ultra-wideband radar regulation with standards and controls for between 8 and 16 years in most countries. As a general rule, countries tend to adopt the approach of the FCC (USA) or the EU ETSI standards. Despite this, many places have some minor variant just to be different or have little formal infrastructure to manage the process.
While we are now in a somewhat stable setting, we in the GPR community cannot become complacent; these regulations are subject to review and can change at any time. For example, a minor change in the ETSI standard formatting has grown into a major challenge to update because a few “minor” technical changes were demanded. A stalwart band of a few members of our community has been struggling to get the issues settled. After 4 years of effort, the revised ETSI standard has yet to be adopted and GPR in EU remains in regulatory limbo, although hope is in sight.
All GPR users should understand that they need to respect the regulations and try their best to adhere to the rules. We also must not allow rogue vendors of uncertified equipment to cause incidents of interference that will re-open the regulatory issues and put the whole GPR community in jeopardy. A major incident of interference could cause a serious review of the liberties we now enjoy.
So, before buying a GPR, ask the vendor for the FCC or Industry Canada identification number or, in Europe, the declaration of conformity, and look for the required sticker on the unit. If the GPR does not comply, protect yourself and the GPR industry by taking your business elsewhere. Don’t just accept a verbal reassurance; get the facts. In Canada and the USA, there are web sites that identify explicitly manufacturers and the products that are approved.