Conceptual design of Doppler shift spectroscopy diagnostics for INTF

•Doppler Shift Spectroscopy diagnostics for ITER DNB at Indian Test Facility is conceptualised for neutral beam characterisation.•Modelling of the system suggests that 36 Line of Sights is required for a complete mapping of the beam.•A novel method of deconvolution of beam focusing effect in the total width is performed.•The error in divergence estimation of the 7 mrad focused divergent beam is less than 10%.