Depending on the type of observation, the requirements of frequency and time-resolution, number of Stokes parameters required, minimum number of pulses folds to be performed, etc., were analysed to maximize the performance and determine the corresponding memory size for temporary storage of data during the processing and the associated maximum data rates at the outputs. The maximum time resolution and the number of channels are, of course, limited to that provided by the FFT module. Also, the results are standardized to fit into 32-bit numbers, irrespective of the type of the processing performed. If finer time resolution is required, the output data can be formatted to fit into smaller numbers ( fewer bits per sample ), by simple changes in software, to achieve higher output data rates.
The processing required for average profile studies is computationally most complex, since it involves all operations such as folding, adjacent sample integration, grating, Faraday de-rotation, de-dispersion and Doppler acceleration correction. This needs a scheme where the available memory resource can be redistributed between Stokes parameters, frequency channels and time frames depending on the type of observation. Even though the implementation of all the above functions is possible using a cascade of individual blocks of dedicated logic circuits, it is not easy to rearrange / bypass different blocks depending on the type of observation. Alternatively, the use of a microprocessor based system suits well to provide such a flexibility. In such a system, one has to simply change the program code for the processor to handle a different processing task. The hardware optimisation and programming skills can exploit the architecture of the processor to enhance the speed performance of such a system. A parallel processing architecture based on DSP chips is an optimal choice. The signal processing algorithm is well suited for implementation on a DSP-chip architecture. In particular, ADSP 21020 from M/s Analog Devices match well with the requirements and has been used for this application.