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

Background

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.

Thesis Objective

The objective of this thesis is to improve the signal-to-noise ratio of the EC instrument by:

1. Evaluating the performance and limitations of the existing oscillator design and possibly finding the root of the problem.
2. Proposing and implementing design improvements or alternative oscillator architectures with improved frequency stability.
3. Quantifying the impact of the proposed solution on the overall performance of the EC instrument.

For a successful thesis work, we believe that the applicants should have:

– 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.

– Practical experience in electronics, such as schematic design, PCB layout, and soldering, is considered a plus.

–  Good knowledge in both Swedish and English.

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.

Application:

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.

We screen and evaluate applications on an ongoing basis. The thesis project may be filled before the application deadline.