Electrical Wiring Interconnect System
EWIS, TDR, OTDR, time-to-digital Converter, time tagger, digitizer, impedance matching, signal integrity
The term Electrical Wiring Interconnect System (EWIS) originates from aviation safety regulations (such as FAA 14 CFR Part 25 and EASA CS-25 Subpart H) and designates the entire electrical wiring system—including wires, connectors, splices, clamps, and shielding—as a dedicated, safety-critical aircraft subsystem.
EWIS diagnostics and maintenance ensure continuous operational reliability under extreme environmental stresses such as vibration, thermal cycling, and chemical exposure. Modern wiring diagnostics increasingly rely on advanced high-frequency testing methods:
- Time Domain Reflectometry (TDR): Fast electrical pulses with sub-nanosecond rise times are injected into the harness. Reflections caused by impedance changes reveal hard and soft faults such as chafing, crushed insulation, shielding breaks, or contact degradation.
- Fast ADCs and Digitizers: High-bandwidth digitizers sampling at multi-GS/s rates record the complete reflected waveform to evaluate the nature and severity of impedance mismatches.
- High-Resolution TDCs: Time-to-Digital Converters with picosecond timing resolution measure the round-trip Time-of-Flight (ToF), enabling fault localization with millimeter accuracy even along extensive and complex wiring harnesses.
- Fast ADCs and Digitizers: High-bandwidth digitizers sampling at multi-GS/s rates record the complete reflected waveform to evaluate the nature and severity of impedance mismatches.
EWIS diagnostics via Time Domain Reflectometry (TDR): High-speed ADCs analyze reflected waveform shapes for fault identification, while precision TDCs determine the exact location via Time-of-Flight.