Noise characteristics at the ARIES site at Nainital and SAAO Sutherland site. The acspline-fitted curve of ARIES and SAAO amplitude spectra are shown in solid blue and dot-dashed red curves, respectively. The theoretical scintillation noise levels of ARIES and SAAO are shown with blue long-dashed and red small-dashed horizontal lines, respectively, and the scintillation noise level of SAAO (scaled to 104 cm diameter) is also shown with a green dotted horizontal line.