Contents
Signals and Systems in Radio Astronomy
by
B. Srikar (02007001)
Chaitanya Ghone (02007028)
Varun Bhalerao (02007006)
Abstract:
We look at radio telescopes in the context of signals and systems and try to analyse their functioning. Instead of mathematical rigor, we resort to an intuitive understanding of the concepts (without detailed proof). We describe in this spirit the properties of a single antenna, as well as a basic two antenna interferometer in terms of standard system descriptions.Index terms:Radio astronomy, Signals and Systems, Application Poster presentation Example
Introduction:
Let us first take a brief look at radio astronomy. Radio astronomy began in 1894 – Oliver Lodge made the first [unsuccessful] attempts to detect radio emissions from sun. An engineer at bell labs – Karl Jansky – made the first detection of radio waves as “a steady hiss interference in radio transmissions”. This hiss was associated with stars because of the periodicity, and thus began radio astronomy. Now it is a well developed field with different types of antennas and receivers used all over the world. The world’s largest meter-wave radio telescope is in India. Today, these telescopes and detectors are at the cutting edge of technology, far better than those used for commercial purposes.A radio telescope differs from an optical telescope in the sense that we can’t look “into” a radio telescope and see the image. A radio telescope is basically an antenna, with a receiver that stores the received data. The data is processed to generate some sort of an image. In contrast to an optical telescope which looks in a specific direction, the radio antenna “lobes” are rather spread out, giving lesser directionality in observations. Another factor that comes in (which we shall see in more detail later) is the resolution – it is not feasible to create a single radio telescope that has as much resolution as an optical telescope. So, interferometers are used – which are radio telescopes working together to form an image. All this as we shall see, is closely related to the concepts of a “system” processing input “signals” to give an output “signal”.
Motivation:
We were motivated in our choice of this application due to our basic interests in astronomy. Yet, radio astronomy was a field which we had not explored, and wished to take a glimpse at. Looking into it with this point of view, we realized that it was, in great detail, an application of precisely what was covered in the course material. This drove us further into choosing radio astronomy as a system for analysis..
