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Home arrow Archives   The American Surveyor     

Network News Print E-mail
Written by Larry Trojak   
Saturday, 10 April 2010

A 692Kb PDF of this article as it appeared in the magazine—complete with images—is available by clicking HERE

Earl Dudley, Inc. saw the benefits of a reference station network early on. Now, nearly a decade after their first station, they are seeing a lot of new converts to the technology.

Equipment suppliers in a broad range of fields can often go years without a change in their product offering. Not so for suppliers of surveying equipment. In order to keep their customer base satisfied, they must continually offer new and evolving technology, regularly upgrade software and firmware to keep it current, offer instruction and support to educate their users, and more. And the truly successful suppliers don't stop there. Never content with simply responding to a changing market, they often anticipate their customers' needs well ahead of the end-user himself. Nearly a decade ago, Earl Dudley, Inc., recognized the key role that reference station networks would one day play in both traditional and construction-based surveying and began a concerted effort to develop one of their own, first in Alabama, then throughout the region. Today, the company owns and cooperatively operates 80+ separate reference stations as part of a four-state network RTK effort it calls iNET. With additional stations being added almost weekly and new markets evolving for the highly-accurate RTK data, the future for the company--and the technology--looks extremely promising.

A Better Alternative
Founded more than 70 years ago, Earl Dudley, Inc., is a full-service supplier of instrumentation for the construction and surveying industries. Initially focused on restoring customers' instruments to exact manufacturer tolerances and standards, the company has since branched out-- both literally and figuratively--to include sales, consulting, technical support and training. In 1999, according to company vice president, Adam Arrington, they began a move toward installing reference stations with a goal of making an area-wide RTK reference network available to its customers.

"We saw the tremendous benefits a CORS-type network could provide and knew that this was a technology we really wanted to pioneer here in the southeast," he says. "Initially, though, we had to reach out to the surveyors and prove the potential this technology had for them; we did so by showing them how it could improve their onsite productivity. On a daily basis, we said, they had to go out, set up a base and a rover, find their control and often still have to deal with UHF's distance or line-of-sight limitations. With network RTK, on the other hand, they can get out of their truck and within a minute have a survey-grade position that is certified to lat/ long, elevation and state-plane coordinates. Essentially, we showed them how tapping into the power of a network could do a day's worth of their work in a minute. In most cases, that's all it took."

John Dudley, company owner and son of its founder, cites a number of additional network benefits by contrasting it with traditional single-vector GPS.

"In terms of capital investment there is an immediate savings since the surveyor or contractor no longer has to purchase a base and rover. In addition, the network overcomes one of the biggest limitations of a traditional base/rover configuration: its range. UHF transmitters have an effective working range of three to five miles--in rolling terrain it can be much less. By contrast, each network station offers an effective radius of at least 30 miles. Another problem with the single-vector approach is reliance upon traditional reference points--monuments which the customer would typically get from the NGS website. Once they arrive at the actual location, however, they might find that monument damaged, destroyed or removed. Occasionally the coordinate positions might have been entered wrong, or they get to the site and another surveyor has already set his base up, in which case they are done for the day and their productivity rates have just taken a serious hit. For all these reasons, we knew a network approach was the better one."

In 2000, about a year after first looking into establishing a network, Earl Dudley made its first substantial investment to lay the groundwork for iNET, purchasing a number of reference stations from its equipment supplier.

Rock in the Pond
To those unfamiliar with the intricacies of developing a reference station network, the process can be summed up best in one word: "daunting." But the Earl Dudley team's attention to detail makes each installation a personal concern--and one which, over time, they've gotten down to a science.

"Once we identify a location in which we feel a station is needed, and verify that we have a customer there, we call on them," says Shane "Trap" Traffanstedt, technical manager of Dudley's iNET effort. "Then we will Google Map it for blockage and possible reception issues, and finally, go there, to inspect their site. With any issues resolved, we talk to the major decision makers to assure them that their network link will be secure from an IT standpoint. We will then send them a contract that says we're going to install the reference station equipment in their office, we are going to retain ownership of it, and we will maintain it. After some IT work which allows us to come in from our servers to their locations and get the raw data feed from that station, they are up and running. They can immediately begin using the data, another location has been added to the network, and we can move on to the next one."

Customers wishing to access iNET can purchase either a yearly, monthly or short-term subscription, with rates priced very competitively and plans rich in value-added features. Those subscribers who agree to host a reference station--Brown & Mitchell, Inc., a consulting engineering group based out of Gulfport, Mississippi are a good example of this--are given a credit toward their overall subscription rate. While the majority of Earl Dudley's commitments have generally been for year-long subscriptions, they say that, because of the tight economy and projects which last only a couple months, monthly purchases are on the rise.

In assembling the network, Arrington says the company has taken what it calls a `rock in the pond' approach, starting locally with Birmingham as the central point, then spreading outward, covering central Alabama and beyond. "Then we established a reference station at our Nashville office and repeated the process there," he says. "It has proven a very successful approach and allowed us to get really decent saturation throughout most of the area."

Network of Networks
As if entering the world of reference networking wasn't challenging enough, Dudley's venture has been made even more interesting by a switch in equipment suppliers--a change which at first seemed to come at the worst possible time, but ultimately ended up being a very positive thing.

"When we initially started developing iNET, we were a Leica dealer, so a good number of the stations installed in the early- to mid-part of the program are from that manufacturer. However, due to a change in circumstances, we became the Topcon dealer for the area. That could have been a real setback to our network effort, but instead proved a blessing in disguise: Topcon was outstanding in their immediate commitment to help us continue growing the network. In some cases we left the stations as they were. In others we removed the older equipment and replaced it with new Topcon gear."

One of the things the Dudley team quickly realized was that intermixing different brands yields different performance. That opportunity to operate networks from two different manufacturers--in many cases providing duplicate coverage--has proven to be a real plus from a standpoint of performance testing, comparisons and contrasts of software capabilities, etc.

"Soon we were taking different rovers from all the major manufacturers out into these areas to see how well they would perform based on what network they accessed," says Traffanstedt. "We have TopNET on one server and Leica's network software with a different IP address on another server. Now, when we go to train a rover user, depending on where they are working and where we have coverage, some dial into TopNET, some into the other server. This provides a valuable opportunity for Topcon to see how well other units work on their network and make whatever changes it sees fit to accommodate them."

Finding New Markets
With nearly 80 reference stations currently in place, Arrington says the main push at Earl Dudley is to continue growing the network, to fill holes in coverage and to build upon evolving markets.

"One positive sign we are already seeing is the increased acceptance of network-based 3D machine control. Most construction sites, because they generally have excellent line-of-sight, still rely upon a conventional base/rover setup. But that's starting to change with the improvement of radio technologies and as they learn more about how a network like iNET can benefit them.

Until recently, one of the key sticking points in reaching larger contractors was the fact that, on a large jobsite, multiple machines—a pair of scrapers and a dozer, for example—usually need to be receiving RTK at the same time. To offer an alternative to paying three separate network subscriptions, Traffanstedt says they created a `site license subscription.'

"We provide what we call an RTK bridge, essentially an internet-directed modem with a radio transmitter built right into it," he says. "The bridge grabs the data from our server and rebroadcasts it to the local project site. That single unit is considerably less costly than a full GPS station, and it eliminates the cost of individual data plans. Essentially, we are giving the machine operators the equivalent of a wireless hub. Only instead of wireless it is via radio."

Watching for Movement
Deformation monitoring is another area Earl Dudley sees as evolving and ripe for network RTK. Companies, municipalities, states, and government agencies that are responsible for monitoring the movement of critical structures such as cooling towers, bridges, skyscrapers, dams, and so on, can install a permanent GPS station on the structure and continually monitor its movement. Being able to do so on a round-the-clock basis through a network, makes that not only possible but affordable.

"We are also really excited about the role we see RTK networks playing in the growth of survey-grade GIS," he says. "One of the best examples of this already took place in Hillsborough County near Tampa Bay. The county hired a consultant to locate--to survey grade accuracy--more than 85,000 manholes. And they wanted it done in a year and half. The consultant used an RTK network to provide the control so they had consistent coordinate locations that were very accurate over a large area. This took a project that would have been economically unfeasible using traditional means and workforce, and made it do-able."

Keeping it Up is Key
Given how far they've come, the positive response they've gotten from customers and the outstanding level of support Topcon has provided, the team members at Earl Dudley are understandably optimistic about the future of iNET. They are equally realistic, however, that the challenges lying ahead will be more and more complex.

"Topcon has really gotten behind our efforts with iNET," says Arrington, "both in terms of straightforward technical support and by allowing us to access some of their latest technology like the NET-3G receiver which can access both GPS and GLONASS, but is also designed to track the Galileo constellation of satellites when it is up and running."

He adds that, as the number of rover subscriptions grows, the support load has been changing with it. "Running servers, doing IT work, handling connectivity and security: all these and more keep Trap busy on an almost nonstop basis. We recognized very early on, that, because network reliability is key, we needed a single person dedicated to this facet of the business, and Trap has really risen to the occasion. The end result of all his efforts--as well as that of others in the organization--is an impressive network uptime rate of about 99.8%. We are really excited about the future of iNET and feel that it, and other GPS networks like it, represent the future of geodetic control. Because we got in on the ground floor, so to speak, we are better poised than most to meet new challenges as they arise. But, then again, we have a 70-year history of doing just that."

Larry Trojak is a communications writer for his own firm, Trojak Communications of Ham Lake, Minnesota. He is a frequent contributor to construction and survey magazines.

A 692Kb PDF of this article as it appeared in the magazine—complete with images—is available by clicking HERE

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