GMRT Software backend (GSB):

I have developed a 48 nodes linux cluster based a 32 antennae, 32 MHz, dual polarization, fully real-time Software back-end for the GMRT. This can play the dual role of a correlator and array beamformer. The highly optimized compute pipeline uses cache efficient, multi-threaded parallel code, with the aid of vectorized processing. This backend allows flexibility in final time and frequency resolutions, and the ability to implement algorithms for radio frequency interference rejection. The software back-end approach, has allowed relatively rapid development of a fairly sophisticated and flexible back-end receiver system for the GMRT, which enhances the productivity of the telescope. This is the first instance of such a real-time observatory back-end for an array telescope like the GMRT. The GSB is now released for regular GMRT observations, since middle 2010 and replaced the old GMRT hardware backend.

GSB cluster :

• A linux cluster of 48 Intel Xeon nodes with three layer architecture
  The first layer consists of 16 acquisition nodes, Xeon 2.4 GHz single core dual processors, each having a 64 bit PCI based four channel ADC card. The second layer consists of 16 numbers of Xeon 2.3 GHz quad core dual processor nodes. The third layer consists of 16 numbers of Xeon 3 GHz dual core dual processor nodes. These 32 dual/quad core nodes share the load of main processing pipelines and recording of the output result. The final product get recorded into a RAID storage. The high speed inter-node connectivity in the cluster is maintained using dual gigabit on-board connectivity.


• GSB baseband recording mode works with quasi-simultaneous data transport from GMRT to NCRA, followed by processing on NCRA Itanium cluster




Current Specifications of GSB :

• 32 antennae, 32 MHz bandwidth, dual polarization real-time back-end with 512 spectral channels at 2 sec time resolution


• Single incoherent or coherent array beam with 30 or 60 microseconds time resolution


• Coherent pulsar array voltage at full nyquist time resolution




GSBC performance benchmarks :

• FFT running at 65% of theoritical peak FLOPS given to FFT


• MAC runnig at 92% of theoritical peak FLOPS given to MAC


• Sustained Network performance at 96% of theoritical peak