If you want to get a project from the organisation the first step you should take is to contact them on their Delhi address. The address is following: Director, Directorate of Extramural Research & Intellectual Property Rights, DRDO, West Block 8, Wing 5, 1st Floor, RK Puram, New Delhi-110066. The fax number is given below: 911126170928.
But before going for that one thing you should know is that they don't give episodic grants for a project but believe in associating with the project. But they are open to any new idea and so you will find them giving constructive suggestions to you even if your project is not being approved.