US Patent 7911372 Active imaging using satellite communication system

An active imaging system uses communication satellites to identify the location and physical attributes of a target. A transmitter emits a time-synchronized signal directed to a target. The transmitter radiates L-band RF signals. The transmitter can be positioned on an airborne or ground platform. A constellation of communication satellites receives and time stamps the time-synchronized signal reflected from the target to form an active image of the target. The constellation of communication satellites have multiple roles other than active imaging, such as providing voice and data communications. The time-synchronized signal reflected from the target can be received by multiple satellites within the constellation of communication satellites or by multiple antenna disposed on one satellite within the constellation of communication satellites.