This document provides an overview of the Russian Global Navigation Satellite System (GLONASS). It discusses the history and development of GLONASS in the 1970s by the Soviet Union. It also describes the key components and characteristics of GLONASS, including its coordinate system, time system, satellite segments, signal structure, and services. Precise details are given around GLONASS' carrier frequencies, code modulation, data transmission, and navigation message framing.