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September 16, 20138 min read

Analog: The narrowband answer for Virginia utilities co-operative


Tait MPT 1327 system meets utility’s needs.

Rappahannock Electric Cooperative case study

Photos courtesy: Rappahannock Electric Cooperative

Faced with frequency squeeze, a federal agency deadline and communications kit from the 80s, Rappahannock Electric Cooperative (REC) formed a co-operative with four other Virginia state rural utilities to find an end-to-end solution for their narrow banding issues.

The answer: a Tait 220 MHz MPT 1327 radio system with IP backhaul.

REC now serves about 157,000 members with more than 16,000 miles of line in more than 22 counties and, in the aftermath of winter snow storm ‘Saturn’, managed over 40,000 radio calls during six days.

Read more to find out how.

(article reproduced with thanks to Mission Critical Communications).

By Dennis E. Buchanan, Rappahannock Electric Cooperative.

In 2000, Rappahannock Electric Cooperative (REC) in Virginia began systematically replacing computer equipment to make the office environment more efficient. The transition was from an AS400 computer system to a desktop environment. That led to the replacement, upgrade and expansion of the microwave system to handle more bandwidth between the main office and the district offices.

The last piece of older technology in use by REC was the radio communications system. The equipment was installed in the 1980s and remained active with an ever-diminishing availability of spare parts. The 153 MHz conventional system used Private Line (PL) tones to separate traffic usage on two frequencies. Channels had to be selected based on location to the nearest tower. Only one conversation per frequency was possible.

REC began looking for new solutions to determine what would be involved to upgrade or replace the old system. The cooperative quickly discovered many factors associated with the endeavor. The first was the FCC narrowbanding deadline of 2013. The utility wasn’t sure if the deadline was hard and fixed, if equipment was available at the time to fulfill the requirements and what technologies were on the market.

Rappahannock Electric Cooperative radio coverage area

Rappahannock Electric Cooperative’s 220 MHz coverage across the 22 counties. The system operates seven radio sites.

Another issue was coverage. REC’s system experienced dead spots in the lower southwest corner of the service area, which had to be addressed by the new system. However, utility officials weren’t sure if additional towers would be needed or if there was a frequency that would propagate well enough to not require additional infrastructure.

The last issue was the inefficiency of the system in large outage situations, especially during hurricanes and major storms. When past hurricanes had hit Virginia, only having a couple of conversations at a time slowed the power restoration process considerably. At the time, REC had about 84,000 members throughout 16 counties. In 2003, Hurricane Isabel left more than 79,000 of those 84,000 out of service in a 12-hour period. It took 10 days to get everyone back in service.

As the cooperative tried to become more knowledgeable on what was available, REC brought in a consultant to do a study addressing all of the aforementioned issues and other factors the utility had not considered.

Technology and Spectrum

In 2005, REC and four other Virginia co-ops performed a joint study on narrowbanding and available options. Part of that study was to determine what features were needed, or desirable, in a new radio system. After the study, a combined request for proposals (RFP) was generated for a shared system and/or an individually structured system, if that was desired. Five vendors responded to the RFP and made presentations.

For a number of reasons, the combined arrangement failed to draw much interest. REC decided to move forward and install its own system. Tait Communications was selected to provide an MPT 1327 trunked radio system. The decision was based on the cost and system design. As a cooperative, price is always a major consideration. Cooperatives are owned by the members and not stockholders per se. The cost for any large system is spread out over a smaller number of consumers.

The other systems presented to the co-ops were not end-to-end solutions. REC wanted a system that was all the same product line so there would be no conflict in problem resolution. Another desired radio feature was the ability to signal an emergency to dispatch with the touch of a button. With the MPT 1327 system, using a control channel, that capability was possible.

As the frequency search began, there was an insufficient number of clear channels in the 150 MHz band to achieve a workable trunked system. Throughout the area of operation, a large number of small operators, including school systems, towing operations and limo services, used the 150 MHz band.

REC is situated along the southern edge of what is considered northern Virginia. There were not many channels available in the 450 and 800 MHz band because of heavy incumbent use within those bands, mainly by the large municipal 9-1-1 systems in the region. Much of 2006 was spent on the spectrum issue. There were seven different scenarios about how to solve the frequency problem. In the end, the decision was made to go to the 220 MHz band, where there were no interference issues. In April 2007, a lease arrangement with the National Rural Telecommunications Cooperative (NRTC) for 220 MHz spectrum was procured.

Network Installation

The originally proposed system was for five sites, but after coverage studies, it was determined a sixth site was needed as a fill-in along one of the major highways in the southeast part of the territory. The backhaul would be T1 and make use of the microwave system. With the exception of two towers, every tower asset would also double as a radio site. In the first quarter of 2008, installation began with base stations and backhaul. After those were in place and tested, a drive test throughout the 16 counties was conducted. Coverage came in at 97.9 percent. The switch to the new system began in May 2008. REC switched out the corporate office vehicles first for further testing. The units typically operate on their own with little contact with dispatch except for calls relaying substation arrivals and departures. The traffic was monitored for any problems, and frequent calls were placed as workers traveled about. In June and July, the two district offices were changed. It took about a week to change out all the vehicles in each office.

In 2010, REC underwent an expansion of territory. REC and another co-op purchased and divided Alleghany Power’s electric distribution assets in Virginia. At the completion of that expansion, REC became the largest cooperative in the state and one of the largest nationwide. REC now serves about 157,000 members with more than 16,000 miles of line in more than 22 counties.

A seventh radio site was added in the Blue Ridge Mountains after REC’s 2010 expansion. That site is leased, and it is the only tower site that REC doesn’t own. The site is in the right spot for coverage into the Shenandoah Valley, but with all the hills and hollows, mountains and valleys, it is likely that two more fill sites will be required. Placing them in the right locations is proving to be difficult because most of the region is national forest.

Backhaul and Redundancy

Rappahannock Electric Cooperative radio backup system

REC’s Kim Irving works in the dispatch room, which has desktop units as an additional backup in case the network goes down.

In August 2012, REC upgraded to MPT IP backhaul with redundant nodes. One of the district offices is now the disaster recovery site. The secondary node resides at that location to allow for complete redundancy. There were a couple of occasions when the node was lost before this change, through no fault of its own, and the ability to talk to dispatch went with it. The outages were brief, but inconvenient. Now, the other node takes over. The secondary is online all the time, and in conjunction with the primary, shares operations. The primary node is acting as the control node with the secondary acting as the switching node. These roles can change depending on which node is brought up first. They share the radio talk-channel traffic. One call will be placed through one, and then the next call goes to the other one.

With the change to IP, if a microwave path is lost, the capability exists for the radio sites to automatically reroute. Before, when there was an interruption in the path, corporate traffic rerouted, but the T1 traffic did not reroute because it was hard wired from microwave radio to microwave radio. So depending on where the interruption was, up to three sites could be affected. Now, dispatch never sees the disruption in traffic.

The cooperative has benefited from the system during the storms subsequent to the installation. The new system allowed power restoration efforts to be handled by more than one group, talking from more than one location, with the districts now dispatching in conjunction with central dispatch. With the ability to have multiple conversations — group and private calls — at the same time without interfering with others, multiple crews can get directions, handle switching orders and coordinate other tasks. Therefore, faster electrical service restoration is achievable.

A recent example of the increased speed and efficiency was the service restoration endeavor in the aftermath of winter snowstorm Saturn in early March. More than 40,000 radio calls were placed during six days, and those calls consisted of both dispatch to crews and truck to truck.

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