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Expanding the use of aerial downlinks

Expanding the use of aerial downlinks

Technology News |
By eeNews Europe



At Integrated Microwave Technologies, LLC (IMT) we developed a turnkey approach to aerial downlinking for military and government users who need IP streaming and receivers for decoding and encoding, as well as installation and troubleshooting.

The situation

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 equipment

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.

The results

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. Proprietary systems will limit the ability to share feeds, ultimately costing additional money and potentially the loss of valuable aerial platform during budget tightening. With the universal COFDM standard, a multitude of receivers are available, ranging from a small body-worn application to a county- or state-wide system.

The products

IMT’s SkymasterTX aircraft transmitter features both MPEG-2 and MPEG-4 encoding, BCRYPT AES encryption and COFDM modulation. All this is packaged in an airframe-friendly NVG ARINC fast-deployable rugged chassis, intended to be mounted directly into an aircraft’s console. SkymasterTX is designed for any application requiring reliable video downlink from an aircraft. Fire departments find SkymasterTX to be specifically useful due to its effectiveness with infrared cameras, as they can view a fire from the air and see where all the hotspots are, without having to send personnel into a dangerous situation. Law enforcement also finds this system useful in monitoring a potentially dangerous system from above.

For small, light-weight applications, the STx transmitter is an MPEG-4/COFDM transmitter that delivers HD/SD output at 250 mW, occupies less than five cubic inches at 0.16 lbs and can be mounted on virtually any small vehicle.

IMT also designs a broad range of receivers. For example, police receiver applications differ from those for firefighters: today’s police cars are filled with technology, basically functioning as a mobile command center. In contrast, the typical fire truck is usually equipped with a standard two-way radio, with its command center set up on site. Law enforcement customers typically have several central receive sites overlapping each other, with a control center for the whole network. For firefighting applications, most of their work is done outside of the truck, requiring a more mobile solution. This way, regardless of where you are in relation to the fire, you have access to the video feed from the helicopter above.

The Mobile Tactical Receiver is a diversity COFDM receiver that will receive the downlinked transmission and stream the video directly to the police car’s in-board computer system device, where the video is decoded and displayed. This allows a police officer or detective in the squad car to monitor a suspect’s activity from the road. This enables officers to make a visual identification and execute an arrest much more smoothly.

The Mobile VIEWER is a self-contained receiver and decoder with a display unit. This is suited for viewing downlink video on a self-contained package. It is specially designed to function under the rigorous environment requirements of a firefighter. It is lightweight, waterproof and fits inside the pocket of the fighter’s jacket. An advanced version of the Mobile Viewer is the mobilCMDR. It features video and audio outputs allowing the video to be displayed on a large-screen display, dismountable antennas and an outboard high-endurance battery capable of six hours of run time.

Figure: The MobilCMDR is a COFDM handheld receiver that can also send video over Ethernet to remote software or hardware decoders, allowing multiple remote viewers to monitor the same video simultaneously.

The Portable Suitcase Receiver (PSRx) is a remote strategic command-post receiver. It features a large-format display (23 inches) daylight readable monitor, and a multiband diversity receiver with a DVR and dismountable antennas for improved range. Now real-time video can be received and shared on a large self-contained system. The PSRx is designed to be a temporary command center for when you are in a remote location where you don’t necessarily have a truck. This is especially useful in covert applications, as it discrete and can be easily set up.

For a sniper, the SRx is a body-worn diversity receiver. It receives the downlinked video and can output the video to a heads-up or monocle-display system. This provides the sniper with even more situational awareness.

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