Terrestrial broadcasters have long accepted, if not always embraced, the concept of sharing space in the RF world. In North America, it is common to find transmitters from two or more broadcasters inside the same RF plant. These same broadcasters often move their signals through channel combiners en route to their antennas, often mounted on the same tower.

That spirit is shared by broadcasters around the world, with some variations by region. In Europe and Latin America, broadcasters often rent space for their transmitters inside buildings or shelters alongside other tenants, some of which may use space for non-broadcast applications. The general concept of the broadcaster sharing space with other tenants is nonetheless a longstanding and often necessary tradition, and one that won’t fade as long as TV and radio content is delivered over the air.

GatesAir is no stranger to this concept given its very large base of TV and radio transmitters installed worldwide. It’s not uncommon to find TV and FM broadcasters sharing space, nor is it uncommon to find GatesAir transmitters installed alongside systems from competitors. In any case, most of these shared-space scenarios feature traditionally designed transmitters, many of which are large high-power systems with several cabinets.

While modern efficiency gains in LDMOS transistors and other technologies have significantly reduced system footprints, these transmitters command a certain amount of space for their cabinets and auxiliary systems. For example, liquid-cooled systems require additional space for pump modules and the plumbing materials that move liquid to and from the transmitters. Broadcasters that share space often do so in very cramped conditions.

Through all of this, broadcasters are always seeking ways to reduce their operational costs. The industry continues to rapidly change, and that requires innovation to help broadcasters keep pace with changing business models and new content delivery opportunities. On one side, we see terrestrial broadcasters tuning into the OTT side of the business: embracing the opportunities that come with replicating linear broadcasts as digital streams, and adding and developing content unique to their OTT services.

But even with the OTT opportunities ahead, broadcasters are in no way set to abandon their transmitters and their over-the-air services. Whether a US broadcaster using its FCC-allotted 19.2MB of UHF or VHF spectrum in one market or a national broadcaster outside North America seeking to fill coverage gaps in their networks, terrestrial broadcasters want new and improved ways to reach larger populations with better service and more content. That includes network operators that manage broadcast channels and services for broadcasters.

The Roles And Challenges Of The Network Operator

Network operators for terrestrial broadcasters are prevalent in most regions outside North America. Often, they represent broadcast-specific divisions of telecom operators, particularly in Europe. These network operators are responsible for the entire broadcast infrastructure and providing reliable broadcast operations through well-maintained systems with appropriate redundancy. These network operators are also often tasked with national coverage in countries with challenging terrain and hard-to-reach populations.

For the broadcaster, working with a network operator provides several important benefits. First, it relieves the broadcaster of having to invest in their own transmission equipment and engineering team for maintenance, leaving them to focus on content and advertising. The broadcaster pays fees to leverage the network operator’s existing broadcast infrastructure, which is built to provide the broadcast capacity to those that want to deliver content to a specific market or population.

The network operator therefore benefits from high-density transmission systems, often deploying and managing multiple racks of low-power transmitters, transposers, and gap fillers to cover entire nations. These systems typically reside in a large headend or shared telecom and broadcast facility.

But what about the network operator that needs something less extensive and more focused to a specific region? About two years ago, GatesAir entered conversations with a Brazilian broadcaster that had a very specific application in mind, and a very specific problem to solve. Brazil is a challenging country for a broadcaster to cover, with both extremely dense cities and widely dispersed rural areas. Many broadcasters have rolled out at least portions of their digital TV systems, embracing the unique aspects of the ISDB-Tb standard, including remux capability, to reliably deliver over-the-air signals over expansive urban and rural regions.

Many small towns in Brazil have been slow to embrace digitization, and expect to remain analog-only for some time. The Brazilian government had hoped to accelerate digital TV adoption through a repack auction to fund their initiative. The concept at the time was to house multiple low-power transmitters in the body of a mast which would be in each town. Additionally, there was a strong desire for them to be convection cooled, as there would be no air conditioning available.

The concept clearly required an innovation that would evolve the long-standing tradition of broadcasters sharing space for their transmission systems. The global engineering team at GatesAir went to work and created an energy-efficient chassis that could house up to six 70W digital transmitters. That innovation, the Maxiva IMTX-70 IntraMast transmission system, can now support up to eight transmitters, each of which can be configured as a digital transmitter, translator, or gap filler.

A New Threshold For Density

In Brazil, the network operator model is similar to what we see in Europe: they install and operate the infrastructure, and then lease broadcast capacity to broadcasters. However, housing multiple tenants in one chassis versus housing standalone transmitters in a headend or RF plant introduced new problems to solve.

With multiple tenants in one chassis, it required incorporating a control architecture and security system whereby the network operator responsible for operations could receive alarms, reports, and more detailing the health and status of each broadcaster’s operation. The system also had to be designed so that broadcasters could access only the modules (i.e., transmitter, transposer, or gap filler) that they had leased. This has essentially brought new meaning to the concept of multi-tenant broadcasting.

Along with new problems to solve come the unforeseen benefits that a single-chassis, multi-tenant design can offer. Using the IMTX-70 design as an example, each of its eight slots can support a different broadcaster. Among the benefits for the network operator is the minimal real estate required, and the highest possible efficiency for energy costs reduction. Initial capital costs are reduced in comparison to the traditional 19” rack mount transmitters installed in a standard rack. With its built-in combiner that manages the different channels from different broadcasters moving to the antenna, capital costs are further reduced.

Of course, there is only so much power that can be packed into a multi-tenant chassis, The IMTX limits each module to 70 Watts, which makes it a solution intended for serving over-the-air content to smaller towns and villages. Consider the advantages of such a system during a typical digital TV transition, where larger markets that broadcast at higher power take priority. These national transitions later turn their focus to smaller towns and populations that are then serviced via lower-power transmitters. A multi-tenant chassis with each module topping out at 70 W makes it simpler to build out a transmission infrastructure quickly and easily. At the same time, open modules can be used to “fill in” patterns in larger markets where terrain might prohibit coverage with a higher-power transmitter.

Slimming The Architecture For Multiple Tenants

Building unique solutions of course require unique design attributes. That includes making sure that multiple tenants can join the service without difficulty. In the IMTX-70, each transmitter, transposer, or gap filler is a separate module that is installed in the master chassis. Once installed, the broadcaster or network operator selects the appropriate I/O card for content ingest, connects the ethernet port to the network, and configures the channel and power level. The combiner configuration depends on the number of broadcasters using the system. As new modules are added and new tenants come on the air, the combiner will be changed to accommodate each newly added service.

Being a single chassis also means less real estate for supporting technologies. To optimize space for multiple tenants, the IMTX-70 uses an existing modulator that takes up much less space, along with a smaller power amplifier. With multiple transmitters in a shared chassis, extensive thermal testing was required to ensure that all systems remain within the temperature limits of the integrated semiconductors. That is also important as the IMTX is intended to be used indoors or within a protective shelter (such as inside a tower), with the original Brazilian design utilizing a mast without air conditioning. Therefore, the extensive thermal testing also ensured reliable operations for all tenants in harsh environmental conditions.

To serve multiple tenants, there also needs to be optimal flexibility to serve each broadcaster’s different needs. Beyond how to configure the transmission module, an important need for the network operator is understanding how to deliver the content to the transmitter for broadcast. The IMTX-70 can take in content via ASI, TSOIP, satellite (exceptional for the ISDB-Tb remux requirement, for example), or from another TV signal. The tasks are the same as if operating a standard television transmitter in a rack, but the difference is in developing a reliable content transport solution to each transmission module in a way that best serves each broadcaster and audience.

GatesAir’s business for 100 years has been about helping its customer base deliver content. Over many decades that focus has been delivering new innovations with higher operational efficiencies for TV and radio transmitters used by the terrestrial broadcaster, and doing it with the lowest Total Cost of Ownership possible. The IMTX-70 is our next-generation innovation for the multi-tenant broadcast operation, taking the concept of many broadcasters in one building to many broadcasters in one box.