  A new architecture is presented for a Networked Signal Processing System
(NSPS) suitable for handling the real-time signal processing of multi-element
radio telescopes. In this system, a multi-element radio telescope is viewed as
an application of a multi-sensor, data fusion problem which can be decomposed
into a general set of computing and network components for which a practical
and scalable architecture is enabled by current technology. The need for such a
system arose in the context of an ongoing program for reconfiguring the Ooty
Radio Telescope (ORT) as a programmable 264-element array, which will enable
several new observing capabilities for large scale surveys on this mature
telescope. For this application, it is necessary to manage, route and combine
large volumes of data whose real-time collation requires large I/O bandwidths
to be sustained. Since these are general requirements of many multi-sensor
fusion applications, we first describe the basic architecture of the NSPS in
terms of a Fusion Tree before elaborating on its application for the ORT. The
paper addresses issues relating to high speed distributed data acquisition,
Field Programmable Gate Array (FPGA) based peer-to-peer networks supporting
significant on-the fly processing while routing, and providing a last mile
interface to a typical commodity network like Gigabit Ethernet. The system is
fundamentally a pair of two co-operative networks, among which one is part of a
commodity high performance computer cluster and the other is based on
Commercial-Off The-Shelf (COTS) technology with support from software/firmware
components in the public domain.
