You don’t have to be big to trunk
Some small-town public safety agencies and small businesses believe trunking means ‘big system.’ Single-site trunked systems can offer advantages over conventional networks for small to mid-size service providers and dedicated systems.
Trunked 800MHz radio systems are often perceived as two-way communications possibilities only for entities with a large number of users. Unless a system uses at least three channels and a few hundred or more users, many believe that digital trunking is just not prudent in terms of cost and complexity. But do users really need to face high costs and confusing technology decisions with a trunked system? No.
As system capacity becomes constrained while communications needs increase, many smaller public safety agencies, public works units and business and industrial radio communications users are thinking about switching from conventional systems to single-site 800MHz trunking. With adequate planning and training, small to mid-sized conventional radio users-as well as businesses, utilities and agencies that have never used private radio-can make a successful transition to a single-site trunked system.
Initial considerations Leading advocacies for 800MHz trunking are to increase channel capacity, improve the level of privacy and exert more control over the radio system. Operators of conventional radio systems who want to expand the number of users struggle because their channels are near capacity. They begin to look at trunking as a viable option because it supports significantly more users per channel than conventional radio. In some instances, a trunked system can support up to 300% more users over the same coverage area as a conventional system. Lack of privacy limits conventional systems when frequencies are shared by different groups of users. Also, operators don’t have the same control over who uses the system-and when—as they do with trunked radio. When limitations become severe, operators consider moving to trunking.
As radio users investigate trunked systems, they sometimes are overwhelmed by the technology. Advanced features, more components and sophisticated software make installation and maintenance more complex and costly than with conventional radio. However, the increase in cost is justified by such features as group and individual calls, emergency calls, fast channel access and failsoft trunking. Advanced systems add remote programming capabilities, telephone interconnect, activity logging and other features. Trunked systems also come in a variety of frequencies-800MHz, 900MHz, VHF and UHF bands-making selection more difficult. Aside from these considerations, radio users face other decisions: How complex of a system do we need? Should it be configured for wideband (25kHz) or narrowband (12.5kHz)? What hierarchies do we set up for subfleets and fleets?
Making the move The move from conventional to trunked is made less challenging when the buyer, working in conjunction with the radio distributor or reseller, selects a system that can meet his needs but doesn’t contain a great deal of complexity.
Smaller operators (defined as 100 to 600 radio users) now have more to choose from in entry-level trunked systems, which do not have the rich feature set found in bigger trunked radio networks. Manufacturers and dealers are developing systems that allow smaller customers on a limited budget to take advantage of trunking technology. Customers can simplify their choices by selecting a system that contains a pre-configured package of standard features necessary to operate a successful trunked network. The alternative-picking and choosing from a large menu of options-can make system selection and installation more complex than is necessary.
Public safety agencies, public works departments, utilities, businesses and others shopping for an 800MHz trunked radio system should look for a feature package that contains all the core benefits of trunking: fast access, emergency call and system redundancy.
* Fast access-Fast channel access time contributes to system efficiency and is one of the biggest advantages over conventional radio. In any trunked system, the time between pushing the talk button and getting an available channel should be less than half a second. High-speed digital signaling over the control channel in 800MHz systems virtually eliminates delay in obtaining a channel assignment.
*Emergency response-The ability to handle emergency calls quickly and efficiently is another key to trunked systems, particularly for public safety and law enforcement applications. When the user initiates a call with the emergency button on his radio, the request is assigned immediately to a free channel, and if all channels are busy, it goes to the top of the queue. Emergency group notification alerts all users in the group of the emergency request.
*Redundancy-Trunked systems differ in their redundancy, or ability to continue operating in the event of a failure in any part of the system. Some continue to operate in trunking mode, even if the site controller or several repeaters go down. Others revert to conventional mode if a controller fails. Radio operators looking for an 800MHz trunked system should consider redundancy factors.
*System capabilities and features represent only part of the equation in selecting and installing the right basic trunked system. Smaller customers, who might not have the time, budget or technical resources to handle each phase of system design and purchase without assistance, can call on consultants, dealers and manufacturers for help. Particularly, dealers who have undergone training and certification from the manufacturers of the systems they sell can be an invaluable source of information for customers purchasing and installing a trunked radio system for the first time.
Getting up and running After the system is selected, propagation engineering studies must be undertaken to help make channel usage as efficient as possible. As with any radio communications system, coverage is the highest priority. Conventional radio operators converting to trunked, as well as customers installing their first system, should take advantage of computer-aided RF propagation analysis to plan the best possible radio coverage.
The next key consideration is tower site selection. With the entire system covered from one tower site, the location of that site is crucial. Several software packages for modeling radio signals are available to predict system coverage and signal strength from each of the proposed tower sites.
Once the site is selected, the dealer and the manufacturer must complete the installation, which can be done in a week for some single-site 800MHz systems. Testing and training are the final phases before the operator is ready to begin using the new system. Users new to trunking often have to adjust to differences between the two types of radio systems. When the user pushes his talk button, for instance, he must get accustomed to listening for the tone that indicates that a channel is ready.
Various levels of operational support are available from dealers and manufacturers, ranging from basic maintenance, which provides repairs on equipment and technical support over the phone, to a full level of on-site support for customers with large networks requiring extremely short response time.
Smaller customers-even those new to trunking-aren’t likely to need the highest levels of maintenance, but they should consider a basic maintenance contract to take advantage of the expertise available from the manufacturer.
Satisfaction with the choice Customers using an 800MHz trunked system for the first time should experience immediate improvements in channel capacity and efficiency. As communications needs grow, system expansion is possible. And as technology advances, software upgrades keep existing 800MHz systems up to date.
The demand for mobile data has also increased among smaller, single-site users. Data communications capabilities greatly increase the usefulness of a trunked radio system by allowing access to computer-based applications. Whereas the addition of mobile data once required expensive new studies, planning and equipment, modern 800MHz trunked systems make the task much more manageable.
Help is available The major manufacturers of trunked radio systems, as well as radio dealers and resellers, are eager to accommodate smaller radio system operators and potential new customers who previously thought a trunked system was beyond their reach. Last year, for example, Ericsson Private Radio Systems introduced its EDACS Connect system to enable conventional users to migrate to trunking more easily than if they purchased an EDACS system with a full feature set. EDACS Connect was introduced in the 800MHz band to take full advantage of digital communications technology.
New and smaller radio customers no longer have reasons to feel shut out of the advancing wave of radio communications. As frequency issues become more difficult to deal with, the lure of trunked radio and its inherent efficiencies becomes greater. Fortunately for radio customers, the process of moving to trunking these days is easier than ever.
