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SKA Telescope- Central Signal Processor Data Rates Print
May 2013

This article was based on the SKA1 Survey Telescope Central Signal Processor design feasibility white paper dated 2013-0503 and was intended to indicate the magnitude of data rates involved. Figures shown below are for SKA1 Survey only.  They may not be accurate and are for illustration only.

o The SKA1 Survey dishes will be equipped with Phased Array Feeds (PAF) and will cover the continuous frequency range from 650MHz to 1670MHz. Signals from the PAF will be beam-formed at the antenna to produce 36 dual polarisation beams in a single 500MHz wide instantaneous band. This beam data is transported to the Central Signal Processor (CSP) facility where it is further channelized to 2kHz channels and cross-correlations of all pairs of antennas are performed.

o The main inputs to CSP are the data for 36 beams from the 96 survey antennas and the main output are the visibilities generated by the correlator which are sent to the Science Data Processing located in Perth.

o The input into the SKA1-Survey CSP per beam per antenna is:
36 × 1GHz x (8 + 8 bits) x 8/7 oversampling = 76.6GB/s

o If 40Gb/s links are used to transport this data where each link achieves a throughput of 96% of capacity then 20 links are sufficient to transport the data from each of the 96 antennas

o Assuming an average for each baseline and polarization pair of 0.7927 dumps per second, and 32 + 32 bit summations results in:

36 beams x 4560 baselines x 4 polarization pairs x 0.7927 dumps/s x (32 + 32 bits) = 3.97MB/s dumped to the SDP per channel. For a 500MHz signal with 2kHz frequency resolution requires 250000 frequency channels, so using 218 frequency channels gives a total integrator output of 1.017TB/s.

Please read this page  for an idea of finding a technology to handle this level of data rates.