Military Embedded Systems

Enabling live video feeds in UAVs


June 30, 2016

John Payne

Integrated Microwave Technologies

As the president of a technology company, I have seen my share of equipment innovations and trends, some which can be used across a wide spectrum of users. Drones ? to be more specific, unmanned aerial vehicles (UAVs) ? fit that description perfectly. Used broadly, the term can apply to toys that can be used to annoy the family cat in a YouTube video, or it can apply to military and industrial reconnaissance and situational awareness applications that are often matters of life and death. There are some obvious reliability and durability factors that must be in place for the latter.

The core benefits of using fixed and rotary wing drones/UAVs in military applications are well established: for reconnaissance and battlefield situational awareness applications, drone systems can accomplish missions deemed too risky or difficult for traditional manned aircraft. They can sometimes replace aircraft costing millions of dollars.

When considering a drone for a military application, clearly-defined mission requirements, which layout the range, altitude, duration of flight, required payload, navigation, sensors and video or image capture requirements are needed. The mission profile drives the selection of the drone and video platform.

While quickly and easily maneuvering in and around a target area is important, for most applications the ability to get live video from the drone is the real mission-critical aspect. If the drone records the video and has to return to its station to offload that content, key decisions will be delayed. Typically, a drone will use one over-the-air transmission media for control, which requires a minimal amount of data, and a second transmission for the real-time video downlink. In all drone applications, the size and weight of the video system and its power requirements are important, as they can effect flight time.

The system must also be robust. The over-the-air modulation must be resistant to interference and multipath signal reflections. In the old days of analog video transmission, anyone in a video broadcasting situation would rarely use the term “robust” to describe their transmissions from the field. Then came digital and Coded Orthogonal Frequency Division Multiplexing (COFDM) modulation. To a large extent, a problem was solved. Unlike other modulation schemes, COFDM maximizes its parameters for uncompromised reliability. In the presence of interference, it does not back down. COFDM has provided robust, non-line-of-sight video transmission over extended distances for two decades or more.

One technology that is quickly gaining traction within the military-drone community is the ability to broadcast video to multiple devices. While consumer drones rely on WiFi technology to transmit to a single view terminal within a short range, military applications allow for multiple disconnected devices to see a drone transmission, sharing the video across a wide area, wirelessly.

Moving forward, smaller-sized drones with more efficient power systems that allow for additional sensor systems are trending up. Communications systems that will enable command and control of a swarm of UAVs flying in close proximity are also on the near horizon.

When thinking of drones, it is key to remember that it’s still early days in the evolution of drone technology and its regulation. Many emergency management office and police departments have been granted waivers and exemptions to operate UAVs and are just starting to explore this technology. For applications within the U.S., the FAA is playing catch up on the technology to some extent, for both consumer and professional drone usage. For this emerging trend, it’s also important to watch what’s happening in related markets.

A UAV is a tool, and choosing the right tool for important jobs is critical. While there is superficial similarity between the myriad “consumer” drones and the technologies they carry on board, the issue of reliable live transmission of video requires professional, COFDM-based transmission when used for law enforcement and military applications.