A digital correlation receiver for the GEETEE radio telescope.

Abstract

A 128-channel digital correlation receiver, built for the GEETEE, a low-frequency radio telescope situated in South India and used for continuum, spectral line, and pulsar observations, is presented. The receiver uses a modified double-sideband technique and measures the spectral-line temperatures without switching. Quadrature samples of signals can be obtained by sampling the digitized intermediate frequency (IF) signals of two clocks, separated in time by one quarter of the period of the IF. Visibilities are measured using one-bit correlators. A proposed scheme for measuring the amplitude information of a signal, using a threshold detector, a one-bit correlator, and including the zero spacing in the synthesis, can enable measurements of the total sky brightness.