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Detection of dispersed pulsars in a time series by using a matched filtering approach

Grootjans, Roelof (2016) Detection of dispersed pulsars in a time series by using a matched filtering approach.

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Abstract:Pulsars are fast spinning neutron stars in the galaxy. Pulsars are the result of imploding stars where the matter of the core is condensed into a super dense neutron star. Charged particles are accelerated at it's magnetic poles causing radio beams. Discovered pulsars spin with a frequency between 0.12Hz and 642Hz and causes their radio beams to periodically hit the Earth. These periodic signals are highly stable over time and are therefore suitable for use as a clock signal. It is therefore theoretically possible to utilize these signals for navigation. This is researched in the PulsarPlane project\cite{pulsarPlane}. Signal powers from pulsars are very low, this causes the need for a large receiver aperture and a large amount of signal processing. When the radio waves from the pulsar pass through interstellar medium they get distorted and dispersed. For high bandwidths this dispersion is quite substantial. It is normally required to dedisperse the signal before detection. However if the dispersed pulse shape is known, a matched filtering technique could be used to still detect the pulsar in a noisy time series. This paper will show the effect of dispersion on the pulsar signal at the PulsarPlane's measurement bandwidth of 400MHz. Dispersion decreases the energy contained in the signal causing the signal-to-noise ratio to decrease. By making use of matched filtering and folding the original dispersed pulsar signal can be recovered when the dispersion is low enough. It will be shown that dispersion can make some pulsars undetectable.
Item Type:Essay (Master)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:39 astronomy
Programme:Electrical Engineering MSc (60353)
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