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With the pressure to improve efficiency and control costs, utilities and public works organizations are demanding more from their wireless data communications systems. Many are also facing end-of-lifecycle technology issues as systems deployed over the last decade no longer meet the demands of complex operations. The good news is that today's private wireless solutions are bringing about new opportunities for achieving dramatic improvements in performance.
The Waterford Township Department of Public Works (DPW) in Michigan recently implemented such an improvement, replacing its current system with a more robust technology that dramatically increased communications efficiency. At issue was the high failure rate of the aging spread spectrum equipment in the township's water and sewer SCADA systems. With 65 personnel supporting 63 pumping stations, 11 water treatment plants, 3 storage tanks, and over 700 hundred miles of water and sewer lines in a 36 square mile area 35 miles northwest of Detroit, Waterford couldn't afford to have an unreliable wireless data system.
"Communications equipment failure was becoming a problem we could no longer live with," says Terry Biederman, P.E., the township's Director of Public Works. "Our spread spectrum solution was reaching the end of its lifecycle, and we were logging in massive overtime hours for maintenance and materials. We looked at changing to a licensed UHF wireless solution, hoping to alleviate some of the issues. When the upgrade was completed in February 2004, the improvements in communications reliability exceeded our expectations."
Enhanced Equipment Power Enables Reduction in Wireless Data Infrastructure
At the heart of Waterford's communications challenge was the limited transmission power of unlicensed spread spectrum radios. "The unlicensed spread spectrum solution limited the amount of transmission power to 1 watt and, consequently, required more repeaters, larger antennae, taller towers, and clearer lines of sight." The limited power also resulted in signal drop out with only minimal amounts of ice on the antennas and water penetration into the cable or connectors.
When Waterford replaced its wireless data system, the jump from the unlicensed 1-watt spread spectrum equipment to the licensed 5-watt UHF wireless equipment yielded a dramatic improvement in communication reliability. "The 5 watt propagation study concluded that we would only need one repeater on top of a water tank to cover our entire service area," he explains. "We also discovered once installation of the radios began at the sewer and water sites that the antennas could be mounted right on the SCADA panels at heights of only 6 or 7 feet. This saved a tremendous amount of installation time and will result in easier maintenance. In our case, obtaining the 5 watt license in a couple of months was also a nice surprise, especially considering our proximity to Canada."
With the 5-watt license secure, DPW personnel began implementing the solution in a pilot test mode, installing just the repeater, central radio, and one remote site at first. Once this was completed and the necessary adjustments were made, the process continued until all 76 additional sites had been converted. "Being able to dismantle the existing towers at many remote sites made many residents happy," he says. "Even with the greatly reduced height of the antennas with the new 5 watt system, we often reduced the power to 2 or 3 watts and still obtained excellent signal strength."
Elimination of False Alarms Dramatically Reduces Maintenance Overtime Costs
Once Waterford implemented its licensed wireless system, the DPW saw a dramatic reduction in alarm calls for its maintenance crews. "Communication alarms had become the bane of our operation," says Biederman. "Most of the time the communication alarms were false and resulted in our personnel treating them as if they were crying wolf."
The major reason behind the false alarms was the lack of power in the township's spread spectrum system. With one watt of power, each of Waterford's SCADA units had little margin of error. "Every glitch, every source of interference could cause what we call a commfail," he says. "When one of our people received an alarm, he would have no idea whether the malfunction was with the equipment at the site or the communications equipment itself. In all cases, someone would have to investigate the problem, resulting in mounting overtime and materials costs."
"The new solution instantly eliminated the communication fail problem," says Biederman. For his personnel, the time and material savings have proven significant, reducing alarms by as much as 100 calls a week. "Before we implemented the licensed wireless system, we constantly struggled to keep up with the alarms, which resulted in other work not getting completed. Now, communication fails are non-existent and personnel can concentrate their efforts on more productive activities."
Licensed Wireless Bandwidth Ensures Continued Reliability
Waterford's new system gives DPW crews the dependability to ensure continuous connectivity. "The bandwidth that we're using to deliver telemetry data is important. Any interruption could prove costly," Biederman explains. "That's why, in the future, I don't want to be using a system in which I might be sharing bandwidth with somebody's cordless telephone."
In addition to enhanced performance, Waterford's system also delivers real-time radio diagnostics. "We now have real-time internal diagnostics of the radio and other parameters, such as forward and reverse power, as well as signal strength. Some of these parameters are even incorporated into our alarm system, so that our personnel can be alerted to potential problems before we have a complete communication failure. Knowing what the problem is also shortens the response time needed to correct it."
For the personnel that keep Waterford's water and sewer systems running, the advantages of having the licensed wireless technology in place are paying off in terms of efficiency and cost savings. But, as Biederman points out, it is the predictability that is driving the success of the new system. "There is a place for spread spectrum technology," he says, "but for us, a higher level dependability and control was mandated."
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