EXPANDING THE USE OF AERIAL DOWNLINKS
John Payne IV, IMT Chief Technology Officer
08 Mar 12. Today, airborne downlinks are no longer limited to strategic command applications. More and more, first responders, fire departments, EMS, CBP and others are employing airborne downlinks to meet a diverse array of needs. Through the use of digital downlink technology, these systems are easier to use, eliminating the need for highly trained technical personnel to operate them. They also now have full-featured infrared cameras and secure digital COFDM transmitters, allowing users to share the video intelligence, surveillance, and reconnaissance information across multiple organizations and agencies.
Integrated Microwave Technologies, LLC (IMT) has developed a turnkey approach to aerial downlinking that provides military and government users a unique, custom, all-inclusive solution. From IP streaming and receivers to decoding and encoding, as well as installation and troubleshooting, IMT’s custom solutions provide great benefits to its customers.
Whether the downlink platform is a fixed-wing aircraft, helicopter, unmanned aerial vehicle (UAV) or even a rapidly deployable blimp, these vehicles carry with them an arsenal of high-quality imagers. These imagers can be daylight cameras, infrared cameras or other sensors capable of chemical or biological detection. Infrared imagers are able to see through smoke from an industrial fire or track a perpetrator under the cover of darkness. Depending on your operational need, these platforms can be positioned far away from the situation — covertly spying on a perpetrator — or right on top of it.
The video from the aerial platform has a tremendous value to operations. Sharing this effectively requires a digital downlink transmitter. The transmitter accepts the high definition video from the imager or other onboard sensor and compresses the video so that it can be transmitted in an effective manner. The compressed digital video is then encrypted using a universal standard AES encryption method known as BCRYPT. The encrypted signal is then applied to a COFDM RF modulator and transmitter, which takes the data intended to be transmitted and converts it into a format optimized for aerial downlink transmission. The transmitter is set to transmit at a specific RF frequency; typically between 6.4 GHz and 6.5 GHz, and is divided into twelve discrete channels. It is important to understand that these bands require a license and often require coordination with a local frequency coordinator.
Once the signal is prepared for transmission, the RF output of the transmitter is connected to an antenna system. This system can be composed of a single omni-direction antenna, or a more complex hybrid-directional or a downward-facing antenna. Several factors dictate the type of antenna system needed for a specific application. The terrain of the area will determine the best type of system, as mountainous and city locations require a different solution than a more rural area. Also, the distance between receive sites is a major factor.
Once the video has been transmitted, several individuals can review it simultaneously. Sharing real-time video minimizes the need for voice instructions over a two-way radio. The video is typically transmitted back to a strategic command center, where it is displayed on a display wall and archived for forensic use. This type of video is especially useful for tactical operations. Video can be shared with such ground personnel as, for example, a firefighter looking to position water for optimal effect, a policeman in a squad car helping to identify suspects during a drug intervention or even first responders needing video surveillance during a rescue.
The downlink feed can be used more effectively with the deployment of the right type of system. With the correct camera, encoding, BCRYPT AES encryption and COFDM digital transmission, video can be shared without bounds. P