US Defense Advanced Research Projects Agency (Darpa) has successfully tested its Video Synthetic Aperture Radar (ViSAR), a sensor that allows pilots and operators of aircraft see through clouds and capture real time video from behind cover.

The goal was to create a sensor that can work just as effectively as electro-optical and infrared (EO/IR) sensors in clear weather. Darpa has said that this project was started in 2013 and since then, they have been developing an Extremely High Frequency (EHF) targeting sensor that can "see through" cloud cover.

While such technology does exist in the form of cloud penetrating radar often used for satellite imagery, the report points out that ViSAR will fit in with EO/IR gear, inside gimbals that are already on planes.

Another advantage to the ViSAR system is that it can maintain frame rates with enough constancy for pilots to track moving targets on the ground, which was not possible with cloud penetrating radar.

Bruce Wallace, program manager in Darpa's Strategic Technology Office said, "The recent flight tests of the ViSAR sensor marked a major program milestone toward our goal, proving that we can take uninterrupted live video of targets on the ground even when flying through or above clouds."

He added that EO/IR sensors would go blank when they meet with clouds or when flying through them, but the synthetic aperture radar was able to track ground movements of targets, "continuously throughout the flight".

To run the ViSAR tests, the sensors were mounted on standard gimbals designed to hold the EO/IR equipment on a modified DC-3 aircraft flying at low and medium altitudes, says the report.

While the test is reported to be successful, it is not clear when this tech will be delivered to the various branches of the US military or which aircrafts will get it first. As of now, Darpa is working toward making the video interface through software a bit easier to work with.

"Refining the ViSAR sensor's visualization software to provide operators a representation they're used to seeing is the next step in the program," said Wallace. "We don't want operators in the back of an aircraft to need special radar training to interpret the sensor's data—we are working to make the visual interface as easy to interpret as existing EO/IR sensor displays."