Taking AMR/AMI to New Heights

Prologue

More than two decades ago when automated meter reading (AMR) was still in its infancy, many believed this new technology would take the industry by storm and that in a matter of just a few years, AMR would replace meter readers on a grand scale. However, as we now know, that did not happen. Part of the reason it didn’t happen is that simply replacing meter readers doesn’t usually provide ample justification for automating the meter reading process. Moreover, the huge installed base of electro-mechanical meters would prove much harder to displace than most initially thought would be the case, based on early indications.

The other part of the reason that AMR didn’t take off as quickly as expected was that those millions of traditional meters – though limited in their ability to provide much of anything but a meter readout that could be read and recorded easily by a human meter reader – were relatively cheap (well under $50); quick and easy to install; rugged, and extremely reliable over long periods of use.

Finally, there came the realization that utility service territories often demand flexible and sometimes varied methods for reading meters. Hard-to-read meters have a different set of meter reading metrics than meters that are easily accessible and have no pervasive impediments to “first-time read” accuracy and availability. Likewise, commercial and industrial (C&I) meters have different metrics than their residential counterparts.

This realization that all meters are not created equal gave rise to widespread re-evaluations of AMR principles from both user and supplier perspectives. These and other factors eventually ushered in the development of multi-faceted AMR systems employing multiple types of AMR techniques and technologies and embracing a more holistic view of the meter reading challenge.

Wireless Comes of Age

So began the wireless communications era. Almost immediately, unlicensed spread spectrum radio was widely touted as the technology that would finally free utilities from wires and meter readers altogether. However, a spate of new problems including range limitations, spectrum interference and reliability issues compounded by a utility workforce still firmly rooted in the business-as-usual mindset of electromechanical metering kept the wireless revolution at bay for the better part of yet another decade.

Still in search of the ideal one-size-fits-all solution, utilities remained nearly as determined to find their ideal meter reading solution as they were determined to try out every nuance that came along (generally in the form of pilot projects) in hopes that the next trial system would be that solution. But utility managers kept seeing more pitfalls – and more latent costs – looming.

Indeed, it was financial concerns about future operational and support costs – not necessarily technical issues – that kept utilities from buying into any singular technology or supplier on a significant scale; that is, anything more than a few thousand units and usually far fewer than that. Needless to say, this was not the tune that suppliers wanted to hear, but it was being played at utilities of all types and sizes, over and over again. These major impediments to rapid market expansion forced AMR companies to go back to their drawing boards to find ways that these devices could provide a more attractive business case and be built, installed and maintained at a lower overall cost.

Meanwhile, further study of the meter-to-cash process soon showed that inherent cash flow delays associated with the manual meter reading process – not the cost of the meter readers themselves – were actually a far more costly component. It eventually became apparent that advanced AMR networks would provide the best solution to this cash flow delay, allowing utilities to bill using meter readings taken the same day, rather than having to wait anywhere from 30 to 90 or more days from the initial read to payment receipt.

A New Approach…

Clearly, creating an AMR network architecture that would be as attractive and economical for trial, limited scope installations as for 20- or 30-year deployments would require a completely new approach. And, in order to pass financial muster, something truly different would be needed; technology alone would not be enough. To achieve such lofty objectives, the system would have to deliver superior performance, dramatically lower infrastructure costs, minimized maintenance overhead and reduced long-term deployment risks.

At this juncture, many AMR experts point to the use of a fixed based network, the widely perceived “Holy Grail” of AMR technology, to meet the wants, needs and expectations of utilities with wide-ranging service territories and operating characteristics. Given a choice, many if not most utilities would prefer fixed based networks over drive-by systems because of the timely availability of meter data, rather than only when a drive-by truck is driven past the meter. However, fixed based networks have historically had difficulty competing with the inherently lower cost drive-by systems, primarily due to high infrastructure costs and associated support implications.

Until now, utilities have not had a viable fixed based network approach that could satisfy their business cases because of both the initial and the life cycle costs inherent to fixed based networks. That is, fixed based AMR networks have typically needed hundreds (sometimes thousands) of cellular pole-top, or meter-based data concentrators, collectors or repeaters to achieve adequate coverage in a large metropolitan area to reach all or even most of the meters. In addition, mountainous terrains and densely built metro areas further compound connectivity problems and the associated equipment needed to mitigate those problems is usually quite expensive and hard to install and maintain.

Range, Range, Range…

This high infrastructure cost for fixed based networks really has one primary root cause: Range. Radio engineers will tell you (to borrow from the parallel analogy in the real estate market) there are three important things to consider in an economically viable large-footprint RF network: Range, range, and range.

The final step in successfully solving the range problem involves covering large metropolitan and suburban areas with a substantially reduced number of two-way Tower Gateway Base-stations (TGBs), designed specifically to minimize infrastructure while maximizing range and signal reliability.

Sensus FlexNet™ is a patented, FCC-licensed protected spectrum AMI network solution from Sensus Metering Systems, which allows the city and surrounding suburban areas of Birmingham, Alabama to be completely covered with only three TGBs; New Orleans, Louisiana with only two (even before Hurricane Katrina reduced the city’s footprint by more than 60% in September of 2005) with a system that regularly delivers two-way communications ranges of over 15 miles from tower to meters.

This long-range solution was designed by focusing on five key range criteria:

• Use the tallest existing radio towers and efficient high-gain antennas;
• Acquire clear nationwide primary use licensed radio spectrum with a low noise floor;
• Design high power endpoints (2 Watts) with state-of-the-art, all digital modulation techniques;
• Design highly sensitive (-120 dBm to -130 dBm) all DSP based receiver base stations; and,
• Develop meter-to-meter “Buddy” relay mode for hard to reach meters (e.g., those in basements, behind line-of-sight barriers, etc.).

To satisfy the requirement for tall, existing radio towers, Sensus has an arrangement with USA Mobility, a nationwide provider of 2-way data messaging services. The TGB is designed to plug right in to existing USA Mobility site equipment, with installations often taking less than four hours. When a TGB is installed in a USA Mobility base station equipment bay, it is able to share the power supply, existing transmitter and receiver antennas and a VSAT (very small aperture terminal) satellite-based data backhaul connection to the network operations center. And, with this VSAT connection, the use of outage-prone telephone lines for back hauling meter data to the central server can be minimized or eliminated.

A key to high quality performance from city to city required the acquisition of Federal Communications Commission primary use radio spectrum for the best and most reliable network operation. To that end, both nationwide and localized licenses were obtained. This spectrum is 100% primary use; that is, the FCC-licensed network has primary rights to the spectrum, with no other entities allowed to use the channel without permission from the licensee and with interference regulated by the FCC.

Another advantage to the licensed frequency band is that the limits for total RF output power are higher than that for systems using the license-free ISM band, typically between 100 mW and 1W. Power translates directly into range in a radio system. One tower is able to cover tens of thousands of meters. Among other advantages, this means that costs can be amortized over many more devices than is typical for conventional fixed based networks.

The system also uses the latest DSP (digital signal processor) technology in the base stations to make its receiver extremely sensitive; up to -130dBm. In fact, the design of receiver is so sensitive that it can “hear” even the weakest signals transmitted from the TGB and approaches the limits of theoretical physics. This advanced design means that the receiver is able to capture virtually every message from the field, almost without regard to signal strength.

Depend on Buddies

The last and a key technique for increasing the range of the system is a patent-pending technique called “Buddy Mode.” This unique innovation is an operating technique that allows all meters that detect a meter in a difficult installation – such as in a basement, below ground level or inside a metal enclosure – to relay data back to the tower for that meter. The Buddy Mode technique allows for messages to be relayed without requiring any additional airtime, and has the added benefit of being stateless and not needing any routing information such as that required by mesh-type networks. Moreover, this approach greatly simplifies meter installations and requires no knowledge of RF networks to deploy.

For example, if during installation a difficult to reach meter cannot communicate directly to a tower, then it is placed in Buddy Mode, allowing it to send messages to any nearby meter instead of directly to the tower. If any other meter in the typical 1-mile range of the difficult to reach meter can reach the tower, then data for that meter will be relayed back to the tower automatically.

Existing Tower Network

USA Mobility brings an existing nationwide tower infrastructure to the network solution, including over 4,000 tower sites covering over 90% of the population in the United States. Moreover, the TGBs are designed to integrate seamlessly with existing paging equipment, which allows the sharing of power, antennae and data back-haul channels. Installation of the TGB equipment at an existing tower site typically takes less than 30 minutes. USA Mobility is also able to provide a critical service real-time TGB tower monitoring and maintenance. With its UL Certified Network Operating Center staffed and operating around the clock, 365 days a year, can detect and report TGB problems in real-time.

Finally, a nationwide team of network technicians deployed throughout the country can respond and repair problems quickly, efficiently and economically, guaranteeing a high level of availability even under adverse conditions.

The combination of patented technology, long-range radio communications, low infrastructure cost, high reliability and tall towers provide a scalable fixed based network that can take AMR to new highs at virtually any utility anywhere in the country.

About the Author

Marc Reed
Director, Communications Technology
With the acquisition of AMDS in July 2006, Mr. Reed, a two-decade veteran of the metering industry, specializing in systems, software and hardware designs, was appointed Director AMI Communications Technology. Communications engineering groups in Santa Barbara, California and Covington, Louisiana report to Reed. Throughout his career, beginning at Dallas-based defense contractor E-Systems, Reed has specialized in the design and implementation of wireless data links. Reed has won several awards for his work in the communications field and has multiple granted patents and patents pending. Reed holds Bachelor and Master of Science degrees in Electrical Engineering from Louisiana State University.