QPSK MODULATOR FOR X-BAND IRS SATELLITES

Sumitha Deepak, Apoorva Hegde

Abstract: The current work is applied to remote sensing satellites. IRS satellites in the orbits are not only sending data to Indian ground stations but also to other international stations for passing data to different countries. Multiple solid-state cameras are carried by the IRS satellite to operate in the visible and infrared bands that acquires imageries for earth survey such as agriculture and geology. Digital phase modulation that allows transmitting discrete phase angles is more popular and easily adaptable. Among the PSK schemes, the QPSK is adopted as it is relatively easy to realize and gives optimum performance in terms of power and bandwidth compared to other modulation schemes. The unit is realized in MIC form, which is smaller in size and weight compared to earlier ones. The data obtained from onboard camera is transmitted to ground on X-band carrier (8-8.4GHz). Keeping in view the future satellite applications, a QPSK modulator is designed with LVDS interface circuit for a data rate of upto 105 Mbps. The microwave simulation software used is EESOF.

Keywords: Hybrid Coupler, Wilkinson Power Combiner, Thin Film Technology.

DOI: https://doi.org/10.15623/ijret.2016.0516077