Don’t let cable‑borne EMI mask real resonances: shield‑grounded leads for cleaner aerospace vibration data
In aircraft component and LRU qualification, long harness runs and proximity to switching power electronics make cable‑borne EMI the silent spoiler. Even with ground‑isolated or case‑isolated sensors, spectra can be corrupted if the shield path is discontinuous or bonded via pigtails. Restoring continuous, 360° shield‑grounded continuity along the cable and through both connectors typically delivers the biggest step‑change in data quality.
Where the interference really enters
- Mounting path: isolation at the sensor breaks ground loops at the mechanical interface. Ground‑isolated and case‑isolated triaxial accelerometers address this path.
- Cable/connector path: poor shield continuity lets the lead act as an antenna, injecting common‑ or differential‑mode noise into your IEPE chain and masking true structural responses.
Aerospace‑grade signal chain
Sensors
Ground‑isolated triax
Reduces ground‑loop coupling while keeping a compact footprint on dense LRUs.
Case‑isolated triax
Ideal where equipotential management is complex or where additional Faraday shielding is needed.
Cables
Low‑noise, shield‑grounded FEP, 4‑socket to triple BNC; the natural partner for ground‑isolated triax
010T series
Shield‑grounded FEP, with stranded conductors for better fatigue life on moving harnesses or where re‑rigs are frequent.
Implementation checklist for aircraft benches
- Make the shield continuous from sensor shell to DAQ—bonded 360° at both ends (backshells, EMC glands).
- Avoid pigtails and drain‑wire tails; these defeat the shield at the frequencies that matter.
- Route away from switching power electronics and long parallel runs with power looms; keep loop areas small.
- Verify connector condition (tight, corrosion‑free); add in‑line low‑pass filtering at the DAQ for extra margin.
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