Passage: GS Group (before 2013 known as General Satellite) is the largest Russian developer and producer of set-top boxes for television. Since 1991 company has been conducting systematic research and development work and producing radio electronic equipment. Company products and technology concepts are used in satellite broadcasting projects NTV-PLUS, Tricolor TV, Platform HD etc. Total number of TV subscribers using set-top boxes produced by the Corporation in Russian Federation exceeds 7 million. In 2007 General Satellite became the main investor of the integral innovation project:  "Technopolis GS: scientific and technological development territory", which is implemented in Gusev town, Kaliningrad Region.

Question: When did the business start the systematic research and development work?
1991