4 August 2008
Jayanta Roy (NCRA)
"The Giant Meterwave Radio Telescope and its Enhanced Capability with a New Software Back-End"
The Giant Metrewave Radio Telescope (GMRT), located near Pune, India, is a
major international facility for research in Radio Astronomy. The GMRT consists
of 30 fully steerable antennae of 45 meter diameter, spread over a region of 25 km
diameter, operating at 6 frequency bands between 150 MHz to 1500 MHz. The GMRT is
designed to function as an aperturesynthesis array for continuum and spectral line
imaging. The GMRT can also produce single pixel phased array beam with high time
resolution to study compact radio sources like pulsars. Signals from each antenna
is transmitted to a central station where there is a multipurpose backend receiver
to process and combine the signals from the 30 antennae.
In this talk, I will first introduce the signal flow of the GMRT with existing hardware backend.
Then I will present our design and implementation of a software backend for the GMRT (GSB). We
have built a 32 antennae, 32 MHz band, dual polarization software backend. This backend is
based on an assembled distributed memory cluster computing using a Linux cluster of 48 Intel
Xeon nodes. GSB works in realtime mode and also supports high speed baseband recording followed
by offline processing on a supercomputer. It plays the dual role of a correlator and a single
beam incoherent and phased array pulsar receiver for the GMRT. We believe this is the first
instance of such a realtime backend for an intermediate sized array like the GMRT.
This new sophisticated processing possible with GSB will enrich the productivity of the GMRT.
The pre and post detection interference filtering pipeline, implemented in GSB, promises the
increase in sensitivity. I will also highlight our attempt of forming high time resolution
multiple phased array beams using the GSB baseband recorded data. This will enable rapid
covering of large region of the sky with full phased array sensitivity which will open up
new areas of phase space for pulsar search at the GMRT. Continuous realtime transient survey
is the other potential key scientific outcome from the software backend. These will also form
a SKA technology demonstrator.