The current state of digital transmitter technology
Sep 1, 2010 12:00 PM, By Richard Redmond
Long-term costs
Figure 2. Many assemblies make up systems at a typical transmitter site.
Select figure to enlarge.
When evaluating the costs associated with deploying a new digital network, one's immediate thought might be the acquisition costs of the infrastructure equipment needed. However, over the life of a typical network, the upfront costs are paid many times over by the ongoing operating expenses. When planning the deployment of a multimedia transmission network, it's important to carefully evaluate the long-term costs, such as power consumption, delivery and installation, building floor space, site rental charges, lifetime maintenance and repair, and eventual disposal costs. Although the topic of power consumptionseems straightforward, it is often overlooked in the planning and procurement process in favor of purchase price, which can lead to elevated operating costs and reduced profits over the life cycle of the product.
A recent evaluation of contemporary products for digital mobile transmission found significant power consumption differences that, in a few months, covered any price difference and, within several years, paid for the transmitter on the power savings alone. Multiply the savings per transmitter across a typical network, and the savings are quite large.
The size of a transmitter used to be a consideration in a network only if there were sites to which transporting equipment was difficult or where doors had limited openings. However, in today's world of shared transmission sites and multiple overlaid terrestrial media networks, the space available at each of the transmission sites is limited. Increasingly, costly real estate places greater emphasis on the size of the transmitter and, as previously discussed, this is exacerbated by the move to higher power levels.
When planning the network deployment, there are three main ongoing costs affected by the transmitter footprint: cost of floor space, availability of floor space and cost of delivery. However, not so obvious is the impact on long-term costs that parts and modules shipped from either the supplier of a centralized parts depot or an operator would have on the network. Additional costs are incurred for each item shipped; therefore, any reduction in the weight and volume of the units and components can have a sustained effect in reducing operating costs.
The ongoing maintenance of the network factors into cost figures as well. The ability to easily repair units in the field without having to ship massive assemblies back to the factory is a key driver in reducing the ongoing costs of any network. To facilitate field repairability, systems must employ careful, simple design techniques that support simpler RF system and module design to eliminate complex alignment procedures. This architecture replaces the previously complex and widely used approach of maximizing gain stages within an RF module. The earlier approach supported low-level signal distribution with a return to the traditional and more reliable higher-level signal distribution followed by lower-gain modules. The improved method employs lower-gain RF modules that allow for easy troubleshooting and repair in the field using simple test fixtures and rapid replacement pallets. (See Figure 2.)
Another attribute worth investigating when evaluating network options is the commonality of assemblies used in transmission systems. The more common the assemblies across the network, the lower the holding costs of the parts. An ideal situation has the same simple RF pallets used in both low-power, air-cooled systems and high-power, liquid-cooled systems. In this case, the same parts used throughout the system reduce not only the stocking of spares, but also the training of operations staff on field service. This reduced complexity helps dramatically at a time when broadcast RF engineers are not readily available in many markets and a wider range of skills may be deployed to maintain the transmitter network.
Increasingly, stringent rules to protect the environment also have affected the operation of multimedia networks. The movement to Reduction of Hazardous Substances (RoHS) impacts infrastructure products due to the lead used in electronics components, assemblies and paints used on other treatments. RoHS will soon be mandatory in every country. Even if this does not influence an ongoing network operation, it can affect the complexity and future cost of environmentally safe disposal of noncompliant components.
In any network, by the very nature of the design, there will be different sites with different power levels working together to create a seamless coverage for the user. To provide the needed signal levels in some areas, small gap fillers or single-frequency network transmission sites are used to provide consistent coverage. Most broadcast operators are familiar with the installation of transmitters in a building or shelter located at the base of a tall mast. However, mobile phone networks have been successfully using weatherproof outdoor enclosures to hold transmission and technical equipment to reduce operating costs and increase the number of locations in which these lower-power fill-in systems can be deployed. Now, most notably in mobile TV deployments, broadcast networks are starting to use this approach for lower-power systems. As planning begins for a multimedia network, it is important to give careful consideration to this approach, because there are solid benefits, such as lower site deployment and rental costs. The units are typically weatherproof enclosures that hold rackmount transmitters, support equipment, and contain heating and cooling systems.
Selecting technology partners
In addition to evaluating products, prices, features and operation costs, selecting the right technology partner can make the deployment and long-term operation of the multimedia network problem-free and cost-effective. Understand the financial stability of the potential partner. Will they be able to provide support if problems arise? Do they have global service capabilities? Can they help commission and deploy the system? Another critical consideration is whether they have established training facilities so staff will be trained and knowledgeable on the system deployed.
Keys to successful deployment
Planning a digital multimedia network and overseeing the implementation is not a simple undertaking. Diligent evaluation, careful network planning, good financial modeling and critical partner evaluations are all part of making the right choices to ensure a successful deployment from the beginning and over the long term.
To recap, consider these key points as must-haves in the selection process:
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Flexible, software-defined multimedia exciter technology with adaptive correction;
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Operating cost efficiency — best-in-class power consumption;
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Compact footprint;
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Plan for elevated power levels — high power density;
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Leading technology;
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Field-serviceability;
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Fully compliant with regulations — technical and environmental (RoHS); and
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Solid technology partner with support for the infrastructure rollout and the long term.
While examining many of the considerations of building a digital multimedia network, it is imperative to understand the local market consumer trends and business model approach. Ensuring that the network covers the consumers and delivers the content they desire when they want to consume it will ultimately determine the network's success.
Richard Redmond is director of strategic marketing, transmission, at Harris Broadcast Communications.
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