Thesis Proposal - Improved Signal-to-Noise Ratio for Eddy Current Testing

Non-destructive testing (NDT) of conductive materials and components such as steel pipes or wires is often performed using a

technique known as Eddy Current testing (ECT).

In this test method, a carrier frequency from an ECT instrument is applied to an inductive test coil which is placed close to the

test object. The test coil generates a magnetic field, which induces eddy currents within the test object. Any discontinuity, such

as a crack, scratch, hole, or a variation in the material structure, disturbs the eddy currents, which in turn modifies the coil

impedance which is detected by the ECT instrument.

Syntronic has contributed to the development of an ECT instrument capable of detecting quite small defects in materials such as

steel with good precision.

However, even good things can be better! One known issue is that the oscillator for the inductive test coil, of PLL type with a

frequency range of 300Hz – 1MHz, has a certain frequency instability. This causes unwanted small impedance fluctuations in the

sensing coil, resulting in unwanted noise in the detected signal. An improved S/N ratio would give the possibility of detecting

even smaller defects.

• Knowledge and an interest in electronics, particularly in analog electronics, such as filter design and calculations, and

various OP-amp and ADC/DAC solutions and measurement technology.

To give you the best possible support during your thesis, we’d like you to be able to come to the office connected to the project

and spend most of your time working from there.

We look forward to receiving your resume, and preferably, a personal letter in which you explain why you want to write your thesis

with Syntronic.