Public-Safety Agencies Piggyback TV Spectrum
Wednesday, June 09, 2010 | Comments
By Mark O’Brien
Public TV and public safety share more than just the word public in their name. By now everyone knows that TV has converted to digital. What many don’t know is that digital TV (DTV) is still available over the air. Rabbit ears may have been replaced with a space-age antenna, but the ability to watch TV without cable is alive and well. What’s the tie-in to public safety? These same TV signals can also securely and rapidly deliver critical incident data to first responders — providing bandwidth desperately needed for emergency management communications.
Many departments have been augmenting their communications with commercial infrastructure such as cell phones and wireless Internet. These systems solve a big problem for law enforcement but they have an Achilles heel — the infrastructure doesn’t provide dedicated bandwidth. Departments using these systems report low, or even non-existent, bandwidth during emergencies. The only thing worse than having no backup communications is thinking you have a plan only to find it doesn’t work when you need it most.
While TV has been around for 75 years, about 10 years ago everything changed when it switched to digital transmissions. The main difference is that DTV is now a 20 Megabits per second (Mbps) digital wireless “pipe” into which stations put DTV programming. In the old days, one picture and one sound source were all that could be transmitted. If you got creative, you could send data at low rates on a sideband.
Now the entire 20 Mbps is used for digital data delivery, most of which is used to send pictures and sounds to TV sets. However, this same 20 Mbps channel can do a lot more and isn’t limited to content going to TV sets. There is excess capacity that can be used to send any digital content, and the receive device can be a computer. For public safety, this excess bandwidth offers a valuable resource for private content distribution. Technology now exists to send computer data over these digital TV signals. In fact, some agencies are using it to transmit large amounts of emergency information such as blueprints; crisis plans; hazardous materials information; and even live security camera, undercover and airship video. This data is delivered directly to officers in the field at the incident scene. The TV signal just delivers the content, essentially replacing the wireless Internet connection.
An example of a department using this solution is the Clark County School District Police Department in Las Vegas. Partnering with public TV station KLVX-TV, the department used SpectraRep’s IncidentOne technology to make crisis response data available for all 378 schools in the district. When an incident occurs at a school, dispatch picks a school from a list, and all the data for that school is instantly sent to officers at the scene. Officers in their patrol cars receive the information on their laptop computers.
This system recently received the 2010 International Association of Chiefs of Police (IACP) excellence in technology award. Emergency management, fusion centers, fire and other agencies are taking advantage of dedicated DTV bandwidth, improving interoperability and augmenting communications with a commercial infrastructure such as cell phones and wireless Internet. Although not a solution most people are even aware of, DTV is available, built out and ready to offer bandwidth to first responders.
In the coverage map for KLVX-TV in Las Vegas, the shaded area in the middle is the city of Las Vegas. Coverage extends well beyond the city limits into California and Arizona. Imagine what it would take to replicate this coverage? Yet it is being used by the Clark County School District Police Department to deliver data to responders dealing with incidents at any school in the district.
DTV’s strengths include:
    • Already built out and on the air
    • Multimegabit data rates available
    • Professionally maintained by staff engineers
    • Backup and redundant systems already in place (most cases)
    • Encryption support
    • Targetable, controlled distribution
    • Redundant bandwidth
    • Natively multicast, so it can deliver content to hundreds or thousands of recipients at the same time
    • Will not collapse during an emergency like cell phones or wireless Internet
Proprietary encrypted content being sent only to selected recipients isn’t something normally associated with TV, yet it is a reality. But what’s in it for the TV stations to make this resource available to public safety? While the answer to that varies by station, in general TV is being pressed to show value in its over-the-air spectrum. Public stations in particular have a commitment to serving their communities; using excess bandwidth to help first responders isn’t only consistent with that, it’s a primary focus for some. Tom Axtell, the Las Vegas PBS general manager, said that using his spectrum to protect children and improve public safety is its best use. While there are ongoing costs for bandwidth and support, they are similar to other delivery options, and the upfront costs are usually grant funded.
The broad coverage, high data rates and professionally maintained infrastructure are all in place to support TV’s primary business. In many cases, public TV stations are already networked to provide regional and statewide coverage. This is the kind of distribution network that would be designed from scratch if budgets existed to do so. The fact that public safety can piggyback on it is amazing, but real.

Mark O’Brien is SpectraRep’s chief technologist. He designs public-safety communications systems that use nontraditional tools to solve real-world problems. He brings his background in satellite, digital TV, IT systems, IP networking and software design to the new challenge of distributing large files and live video to incident scenes. E-mail comments to
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