An SDR system and method that intentionally illuminates aircraft systems with RF energy having specific characteristics (e.g., frequency, power, waveform, directionality, duration, etc.) are provided. The aircraft systems act as non-linear mixers and emit non-linear RF energy. A receiver receives the RF energy response and generates an RF energy representation that is correlated to a database of baseline responses. A correlation response between the received RF energy representation and any one of the baseline responses from the database provides an indication of the aircraft system status.