City of Houston Collaboration Leads to Innovative Solution for First Responders

Dec. 21, 2015
Using existing broadcast television signals to deliver Public Safety video and data, regional USASI district wins 2015 top award


The need to deliver data, especially video, to multiple users in the field is increasing and public safety networks are struggling to keep up. Dashboard and body cameras, helicopter video, satellite imagery, location data and many other sources reflect the increasing requirement to manage data as well as voice. FirstNet will begin to address this concern and may be even further enhanced by incorporating additional spectrum and capabilities.

Broadcast television has an almost 80 year history of optimizing its wireless delivery network for coverage, resilience and reliability. In addition to the ability to broadcast, television stations are connectivity hubs with extensive content management expertise, vertical real estate assets and other capabilities that are valuable to public safety.

New technology called datacasting bridges these two worlds allowing television broadcast signals to deliver secure encrypted and targetable video and other data to first responders. Datacasting was recently deployed in a pilot project conducted in Houston to provide a new data centric delivery network, take advantage of their native one-to-many broadcast efficiencies and improve interoperability by allowing information sharing across agencies.


Land Mobile Radio (LMR) systems are the cornerstone of public safety communications, but they are still voice centric. At the same time, the amount of data and video being generated, and the urgency to make it available, is increasing every day. Even the latest P25 compliant LMR systems can only share data at rates so low (9,600 baud) that they are impractical for anything other than text.

Clearly new solutions to video and data sharing are needed. FirstNet brings new spectrum and capabilities and is urgently needed, but it is several years away.  Given the apparent trend, additional spectrum and technologies will likely need to be brought to bear.

Multiple Houston-based agencies and organizations partnered recently to test and evaluate the ability to utilize existing broadcast television spectrum to provide video efficiently. Whitespace applications also use TV frequencies but are low power and require building transmission infrastructure. This project partnered with KUHT-TV to use Houston’s full-power public broadcast television station including its licensed spectrum, transmitter, and tower and existing metropolitan coverage to deliver encrypted targetable data to first responders.

The fact that KUHT-TV was willing to allocate a portion of their valuable broadcast spectrum and infrastructure to support public safety is one of the great lessons from this project.

KUHT-TV operates at 65,000 watts from a 1,800’ tall tower on the outskirts of Houston.  They cover all or parts of 13 counties and well out into the Gulf of Mexico.

Over 6.1 million people live within the coverage area of KUHT. They depend on multiple public safety agencies and organizations in multiple jurisdictions to keep them safe. Replicating this coverage with other networks would take considerably more infrastructure.

The station is built to withstand natural disasters, is monitored 24/7 by professional engineers, has backup generators, physical and IT security and other public safety grade attributes that make it an excellent partner for delivering proprietary data.

The Integrated Solution

On July20-24, 2015, multiple public safety users including the City of Houston, Houston PD, the University of Houston, Texas Medical Center, NRG Stadium, Metro PD and the Harris County Sheriff’s Office participated in a joint exercise to demonstrate the ability of datacasting to support public safety communications in an operational environment.

Content management and video resources from existing service providers, including Vidsys and Haystax Digital Sandbox, were incorporated to inject content into the broadcast. In all, over a dozen organizations collaborated to test and evaluate this new capability.

The focus was on improving interoperability by sharing content across multiple jurisdictions utilizing existing broadcast television spectrum. This event also how public-private partnerships can be leveraged to address growing content delivery needs.

The Johns Hopkins University/Applied Physics Laboratory (JHU/APL) oversaw the project. The Department of Homeland Security Science and Technology Directorate provided funding, direction and coordination.

KUHT-TV agreed to provide a portion of their over-the-air broadcast spectrum for use in this exercise and will continue to make that resource available to public safety. SpectraRep installed technology to enable KUHT to deliver encrypted and targetable IP data over their broadcast television signal.

Working under contract to the Department of Homeland Security (DHS) Science and Technology (S&T) Directorate, JHU/APL developed a set of tests designed to evaluate the technical capabilities in an operational environment related to public safety.  As part of these tests, members of JHU/APL, assisted by DHS and local public safety representatives observed the tests, recorded observations and will publish the results in the near future. 

How the partners worked together

During the simulated events, the City of Houston and University of Houston (UofH) successfully pushed their content over the KUHT television signal to their own and multi-jurisdictional users. All content was encrypted using AES-256 encryption. Both individual users and groups of users were targeted, with only those targeted receiving data.

While this was happening, KUHT continued to broadcast normally. The general public watching television had no idea that encrypted public safety data was also being transmitted at the same time.

Simulated events included suspicious individuals entering a dorm on the UofH campus and gang activities at NRG Stadium with suspects fleeing the scene of criminal activity. In both cases subjects were tracked as they moved about and fled the scene. Multiple cameras were used to follow the suspects. Concurrently, data related to the incidents including building blueprints, map coordinates and other relevant files were transmitted to all responding agencies. A cell phone was used to capture a close up photo of the suspects, which was emailed back to dispatch where it was then datacast to all participants.

The simulated events demonstrated both the technical capabilities of datacasting (coverage, video quality, integration, ease of use) as well as its applicability for improving day-to-day public safety information sharing. Preparing for the event included installing equipment at KUHT, installing antennas, receivers and software at all of the participating locations, and training. All of this was accomplished in a matter of days.

The coordinated event was deemed a success based on the following conclusions and findings:

  • All data transmitted over the datacast system – alerts, images, files and video streams – were successfully received by targeted recipients.  Successful receipt was verified by members of the test team and/or the participating organizations.
  • Through the tests and comprehensive equipment checkout procedures, the system provided extensive coverage throughout the Houston metropolitan area. While not specifically tested, anecdotal evidence suggested that the KUHT datacast signal provided coverage in areas that do not have reliable cellular service.
  • Although the datacasting standards do not currently support receipt of data while in a moving vehicle, participating organizations reported the presence of a strong signal in moving vehicles much of the time. A new broadcast television standard (ATSC 3.0) will address this issue and support full mobility and direct reception on cell phones and tablets, even while moving.
  • Law enforcement officers participating in the test reported that datacasting provided video (which is frequently not available at all outside of a command/dispatch center) and audio quality exceeding current capability.  One officer referred to the ability of datacasting to support video streaming as potentially life-saving, and end-user participants made clear their desire to retain the system after completion of the exercise.
  • All participants commented positively regarding both the ease of installation and ease of use of the particular datacasting system implemented in Houston.  Participants in the test were able to use the system effectively with minimal training, most of which was provided on the fly remotely. The datacasting capability will remain in place temporarily while all of the participating agencies continue to test and evaluate.

The July demonstrations provided validation of the capability and utility of datacasting for public safety and law enforcement.  JHU/APL expects to continue to collect data and perform additional analysis to better define the potential uses of this capability and how it fits within the broader public safety telecommunications architecture.

Why is it innovative

Public safety has tremendous challenges and unique requirements when it comes to keeping the public safe. As a result, communications typically involve expensive proprietary systems and radios. The proprietary nature of this infrastructure presents two limitations. Proprietary systems, while delivering a seamless, reliable capability, can often be expensive and are not easily changed or integrated with other systems.

The datacasting exercise was innovative because it combines best-of-breed capabilities from multiple technologies and various industries to provide a solution to the growing problem of data distribution.

There is no better partner than KUHT, Houston’s public television station, to improve wireless video delivery in the Houston metropolitan area. They have been doing exactly that since 1953. Television stations like KUHT-TV are experts in video acquisition, video compression, ingesting content, building resilient transmission infrastructure, backhaul, managing towers and other issues that public safety deals with every day.

Another challenge was addressing the interoperability issues that exist today. Agencies go to great lengths to secure their systems. This security protects content, but creates a barrier to interagency sharing. Firewalls, proprietary networks and other technical challenges limit the ability to share data effectively.

Because the data is broadcast securely over a single TV channel, controlling who has access is simply a matter of allowing or not allowing decryption of the received content. This enables multiple agencies to use the system concurrently and send data only to recipients within their agency by targeting just those specific receivers. However, with proper credentials and access, receivers in other jurisdictions can also be targeted, improving interoperability without adding any other infrastructure or compromising security. Access can be modified at any time allowing for changing situations.

The model that was used in this pilot was that the owner of the content decides with whom they want to share their information. Because it is a push model, the content owner can push it to their own users with the option to include other agencies. They can just as easily revoke permission as needed, maintaining control of their content.

Partnering with a television station like KUHT may seem obvious in hindsight, but looking outside the box for public-private partnerships to solve the growing need to deliver video and other data is innovative. Combining commercial off the shelf (COTS) tools with proprietary systems to create hybrid solutions that are uniquely adapted to specific tasks is innovative and will lead to creative problem solving in the future if it is adopted.

Datacast Technology Overview

Datacasting technology takes advantage of the unused data capacity in existing over-the-air broadcast television signals to encode and transmit additional proprietary data unrelated to delivering entertainment content to television sets.  Secure law enforcement and public safety data is one example, but consumer content including movies, alerts, map data and more can also be incorporated.

Aggregate broadcast streams are currently sent at a constant 19.39 Mb/s data rate (see Figure 1 and Next Generation Standard section below). Various programs are multiplexed into the aggregate stream including High Definition (HD) television (shown in green in figure 1), multiple Standard Definition (SD) programs, audio and metadata (the remainder of the colors in figure 1). Null packets are used to pad the total bitstream to the required 19.39 Mb/s (cross hatch shown in figure 1). Datacasting replaces the null packets with encrypted IP packets which are then received and interpreted by registered recipients with the required devices and software                                                 

 In general, the datacasting system is configured to incorporate four types of data into the datacasting transport stream:

  • Real-Time Streamed Data: Live video streams such as helicopter or surveillance video are the most commonly streamed data. Other streamed information might include audio monitoring, weather information, news broadcasts or other live sources.
  • File-Based Information: This information includes static documents and images, which may also include pre-recorded audio and video clips. It can include other types of digital information including software and firmware updates. Forward error correction (FEC) and “carouseling” are used to assure all packets are received, even in degraded reception environments.
  • Message Based Information: Generally, the messages are Common Alerting Protocol (CAP) compliant messaging, allowing messages and notifications to be processed by any CAP compliant alerting platform.
  • Access Control Information: File-based data is used to control registration and access. This information includes receiver registration, receiver group assignments, protocol assignments, key list assignments, and other background data required to authenticate users and manage decryption.

Datacasting reception begins with reception of the signal by a receiver connected to a computer, not a television set. The receiver can be a USB “dongle”, or Linux based appliance. Any properly tuned UHF or VHF antenna can capture the signal. However, only devices with the required software, decryption, and registration will actually be able to convert the signal and process the embedded data into useful information. Receivers can be designated as individual unique registered recipients or as part of a group registration.

When a device is authorized to receive data, the encrypted IP packets are decrypted for processing by the appropriate application software in the device. Additionally, datacasting can be integrated into other systems to create a return path for two-way communication and services.

Next Generation Broadcast Standard

Television technology continues to evolve and there are changes on the horizon that will provide even more benefits to public safety including:

  • Higher data capacity
  • Enhanced mobile reception
  • Direct reception on enabled phones and tablets
  • Enhanced robustness for building penetration
  • Native IP transport eliminating IP encapsulation
  • Support for interactivity utilizing a separate return path
  • New flexible modulation scheme that enables multipath to enhance reception
  • Support for multiple transmitters (single frequency networks) to improve coverage
  • Hybrid content delivery (combining broadcast and broadband content)
  • Built-in advanced public emergency alerting
  • Extensible framework to support seamless future upgrades


FirstNet will be a welcomed addition to public safety communications.  But, based upon what we know about its implementation, it will be understandably several years away from widespread implementation.  It will likely use the current cellular unicast technology for distributing video and potentially have coverage limitations in rural areas.  Datacasting can provide valuable support in each of these locations: with a limited investment it is available now using existing infrastructure, uses broadcast (one-to-many) technology, and covers 97% of the of the US population, including territories.

Datacasting is not an alternative to FirstNet, it enhances their mission by providing new licensed spectrum with unique capabilities. The public safety grade attributes of broadcast television can be deployed today and continue to enhance communications in the future.

While most consumers currently get television programming from cable providers, broadcasters continue to offer over-the-air content at significant operational expense. Public television stations believe that serving their community involves going beyond offering educational and entertainment television programming. They make excellent partners because they want to see this investment serve and protect citizens in their community.

The datacasting exercise in Houston demonstrated that outside resources like public television infrastructure and datacasting technology can be combined to improve data sharing and interoperability at minimal cost and effort. The equipment currently remains in place and is now being evaluated as an operational capability.