On 22 June 2012 I defended my thesis on "Algorithms for Radio Interference Detection and Removal". The complete manuscript pdf can be downloaded here: Thesis A. R. Offringa.
Propositions
- LOFAR fulfills its high expectations!
- Radio-astronomical observations in populated areas can achieve very high sensitivities.
- Continuous broadband transmitters, such as DAB stations, are currently the most destructive transmitters for performing low-frequency radio astronomy.
- Compared to conventional thresholding, the
SumThresholdmethod is more accurate for detection of interference, and should be used for data from all sensitive radio telescopes. (Chapter 2) - Morphological detection, especially the scale-invariant rank operator, is a good and fast additional step for finding interference. (Chapter 2)
- It is very likely that radio-frequency interference will not prevent a LOFAR detection of signals from the Epoch of Reionisation. (Chapter 6)
- While the introduced low-pass filters are still in its infancy, they appear to be an efficient technique for the attenuation of undesirable relics in the final sky maps. (Chapter 4)
- Sources of interference for LOFAR are approximately uniformly distributed on the surface of the Earth. The propagation of their signals can be well described by Hata's model. (Chapter 6)
- For determining the best location of a low-frequency radio telescope, the average condition of the ionosphere is more important than the amount of RFI.
- Astronomical research will benefit from collaboration with computer science.
- Research can be compared to ballroom dancing: it is important to be able to stand and move independently, but even better results can be achieved by combining forces.
- "By definition" is by definition not equal to "almost always", even though it is almost always used like that.
André Offringa