NEW YORK-Satellite Survey Systems Ltd., a Dallas company with roots in oil and gas exploration, has added another notch in its diversification belt by helping wireless companies pinpoint tower locations using global positioning systems.
The company’s endeavors are part of a trend in the tower-siting business, which for many years had relied primarily on U.S. Geological Survey maps. USGS maps can be less accurate in some respects than versions of GPS systems available today, but that wasn’t necessarily the case earlier this decade.
“As I’ve been given to understand, the technology behind GPS was developed by the Pentagon. Until very recently, the (GPS) devices available to the public, including private industry, were not completely accurate, out of concern they would fall into the wrong hands,” said Sheldon Moss, government relations manager of the Site Owners and Managers Association. SOMA is part of the Personal Communications Industry Association, Alexandria, Va.
“Without the error factor, GPS is pretty darned accurate in determining latitude and longitude and, to some extent, altitude. In a significant number of cases, the industry (now) is using GPS in conjunction with standard U.S. Geological Survey maps.”
Accuracy is a matter of degree, and degrees do matter, according to Lowell Phillips, a spokesman for Satellite Survey Systems and a principal of Investor Compliance and Integrity Audits Group, a Longview, Texas, consulting firm. ICIA Group plans to begin offering soon a tower location warranty program.
“If your tower is 20 feet too low, somewhere along the way the signal goes into the dirt; if it’s 20 feet too high, the signal keeps heading up into the air,” he said.
In positional accuracy audits SSS conducted within the last year for two of its “nationally competitive communications clients,” half of the tower sites “were outside the national mapping standards’ 1-A tolerance parameters,” said Sam Billingsly, company founder and president. That means they were more than 20 feet from where they are supposed to be in a horizontal plane and three feet in a vertical plane.
“When interviewing tower owners … we found that a great many … assumed their tower positions were correct but had no documentation [showing these to be] within regulatory compliance,” Billingsly said.
“Many tower owners are unaware of the extent of the affect of incorrect positioning on revenues and income.”
A 20-foot vertical error can affect a tower’s coverage by as much as 20 percent and a 500-foot horizontal error by up to 3.5 percent, according to several RF engineers Billingsly said SSS has interviewed. Based on this information, Aircom International of the United Kingdom conducted an RF propagation study for SSS indicating a 10-percent increase in gross revenues for correctly positioned towers.
Asked for horror stories from his experience, Billingsly offered several as examples of “the grossest errors we have encountered” in tower positional audits.
One tower in west Texas was off by 200 feet in the vertical from its presumed position in the network. Placing it where it was supposed to be put it too close to the takeoff and landing flight path of a nearby airport. Another had been lifted 30 feet higher than it was supposed to be by earthquake activity in California.
In the horizontal plane, one tower had been built six miles from its intended location due to a typographical error, while another was 10 miles from its presumed location.
