Radio Interferometer Telescope

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Introduction

This project deals with making a astronomical interferometer (a type of a radio telescope) based on the techniques of aperture synthesis. This telescope is designed to work at a radio frequency of 74 MHz.

The basic idea is to measure complex cross-correlation coefficients between voltage signals from two antennas separated by a distance, $b$. This technique, called interferometry, is used to obtain higher angular resolution, which may not be attainable due to modest sizes of individual antenna (or dishes) involved in observations.

Methodology

We plan to use half-wave dipole antennas to sense electromagnetic waves from astronomical sources at $74$ MHz. This signal will be down-converted to $1.9$ MHz using a mixer, after necessary amplification. A small band around 73.9 MHz, of about $0.25$ MHz will be recorded using a direct-voltage recorder system. This raw, 2-bit quantized data will be stored on a PC for a later processing by customized computer programs.

These programs have been termed as `software correlator'. Our code for cross-correlation is based on lookup-table approach, details of which will be available on a separate page titled BITS Correlator.