A system and method for detecting a scrambling seed in communication between a drone and a controller are described. The system comprises a radio-frequency (RF) receiver configured to receive an RF signal transmitted between the drone and a controller. The RF signal includes scrambled data that contain repetitions of unscrambled data based on known scramblers with an unknown scrambling seed. The system further comprises a memory device in communication with a hardware processor and having stored computer-executable instructions to cause the hardware processor to identify the smallest number of bits required in each segment of scrambled data for data combining by finding an invertible predetermined matrix. The hardware processor is configured to determine the unknown scrambling seed based on a function combining the predetermined matrix, transition matrices of scramblers, and segments of received scrambled data.