Explanation:

IRNSS or NAVIC is an independent regional navigation satellite system being developed by India. It is designed to provide accurate position information service to users in India as well as the region extending up to 1500 km from its boundary, which is its primary service area. IRNSS will provide two types of services, namely, Standard Positioning Service (SPS) and Restricted Service (RS) and is expected to provide a position accuracy of better than 20 m in the primary service area.

Satellites

IRNSS-1A: The first of the 7 satellites of the IRNSS Constellation, IRNSS-1A, was successfully launched onboard. IRNSS 1A satellite consists of two payloads – navigation payload and ranging payload, generating navigation signals in the L5 band(1176.45 MHz) and S band (2492.028 MHz) respectively. Three highly accurate Rubidium atomic clocks are part of the system along with corner cube retro reflectors for laser ranging.
IRNSS-1B: The satellite was launched successfully on April 4, 2014 by PSLV-C24. IRNSS-1B is functioning satisfactorily. This was launched to provide navigational services to the region.
IRNSS-1C: The satellite was successfully launched onboard PSLV-C26 on October 16, 2014.
IRNSS-1D: The satellite is the fourth of seven in the constellation, launched after IRNSS-1A, IRNSS-1B and IRNSS-1C. IRNSS starts working after this satellite.
IRNSS-1E: The IRNSS-1E spacecraft was launched on January 20, 2016 on the PSLV-C31 vehicle from SDSC (launch mass of 1425.4 kg).
IRNSS-1F: This satellite besides having the navigation and ranging payload is also carrying a Rubidium atomic clock, which will transmit navigation service signals to users.
IRNSS-1G: Like its other IRNSS predecessors, IRNSS-1G also carries two types of payloads – navigation payload and ranging payload. The navigation payload of IRNSS-1G will transmit navigation service signals to the users. This payload will be operating in L5-band and S-band. A highly accurate Rubidium atomic clock is part of the navigation payload of the satellite. The ranging payload of IRNSS-1G consists of a C-band transponder, which facilitates accurate determination of the range of the satellite.