Reflected Signal Analysis

Forensic characterization of a wireless device is useful in many applications. An example of this is in the testing of Federal Communications Commission (FCC) Part 15 devices that must adhere to strict guidelines with regard to RF interference; one reason being problems with Portable Electronic Devices (PEDs) carried onboard aircraft. The operation of PEDs aboard U.S.-registered civil aircraft is limited. These rules also permit the use of specific PEDs after the aircraft operator has determined that the PED will not interfere with the operations of the aircraft. However, how can the aircraft operator know which PEDs are approved, or if the approved devices are being operated at inappropriate times? Compliance can be verified by detecting the operation of transmitting PEDs (T-PEDs) using an onboard monitoring system, or it could be verified by characterizing the device at a gate entry point, whether powered on or off, using specially designed probe signals and forensic techniques to classify the returned signal. In a more general setting, forensic characterization allows determination of the type of device, make, model, configuration, and other characteristics based on observation of the data that the device produces. The unique characteristics of the device are known as device signatures or device fingerprints.