Dear Abhijith
Defence Research & Development Organisation (DRDO)works under Department of Defence Research and Development of Ministry of Defence. DRDO dedicatedly working towards enhancing self-reliance in Defence Systems and undertakes design & development leading to production of world class weapon systems and equipment in accordance with the expressed needs and the qualitative requirements laid down by the three services.

DRDO is working in various areas of military technology which include aeronautics, armaments, combat vehicles, electronics, instrumentation engineering systems, missiles, materials, naval systems, advanced computing, simulation and life sciences. DRDO while striving to meet the Cutting edge weapons technology requirements provides ample spinoff benefits to the society at large thereby contributing to the nation buliding.
Basically,  good score in GATE can get into DRDO.  but everytime those gate marks changing please take care of that. You can find the dates of  DRDO exam in Google.
All the best. You cab refer remaining solutions for more information.

DRDO every year releases tender floated for recruitment and its rules and dates specific alongwith it.
This tender automatically routes to career website of DRDO where all eligibility criteria is me tioned for different posts and senior roles.
Moreover, Engineers with complete graduation from Electronics or mechanical branch with vakid GATE score is must for recruitment.
The roles offered are for major projects, Development and technologies, Comabt Engineering, Missile and Aeronautical Engineering, Purchase executive an dprocurement manager are some varied roles on platter.
You can be abreast with DRDO website for all details.
Initially salaries range from 25000 to 35000 for junior Engineering posts and junior research assistants.
Goodluck and revert incase of doubts.