Satellite Navigation Services
Services/ Satellite Navigation Services
Satellites for navigation services to meet the emerging demands of the Civil Aviation requirements and
to meet the user requirements of the positioning, navigation and timing based on the independent
satellite navigation system.
GPS Aided Geo Augmented Navigation (GAGAN)
To meet the navigation requirements of civil aviation, ISRO and Airports Authority of India (AAI) have
implemented the GPS Aided Geo Augmented Navigation – GAGAN as a satellite based augmentation system
(SBAS) for the Indian airspace.GAGAN system is inter-operable with other international SBAS systems
like USWAAS, European EGNOS, Japanese MSAS etc. GAGAN provides the additional accuracy, availability,
and integrity necessary for variousphases of flight, from en-route through approach for all qualified
airports within the GAGAN service volume. GAGAN has been certified by Directorate General of Civil
Aviation (DGCA) for RNP 0.1 services on 30thDec 2013 and APV -1 services on 21stApril 2015. More
details regarding GAGAN system and its applications are available at the GAGAN website
Navigation with Indian Constellation (NavIC)
To meet the positioning, navigation and timing requirements of the nation, ISRO has established a
regional navigation satellite system called Navigation with Indian Constellation (NavIC). NavIC was
erstwhile known as Indian Regional Navigation Satellite System (IRNSS).
NavIC is designed with a constellation of 7 satellitesand a network of ground stations operating 24 x
7. Three satellites of the constellation are placed in geostationary orbit, at 32.5°E, 83°E and
129.5°E respectively, and four satellites are placed in inclined geosynchronous orbit with equatorial
crossing of55°E and 111.75°E respectively, with inclination of 29° (two satellites in each plane).The
ground network consists of control centre, precise timing facility, range and integrity monitoring
stations, two-way ranging stations, etc.
NavIC offers two services: Standard Position Service (SPS) for civilian users and Restricted Service
(RS) for strategic users. These two services are provided in both L5 (1176.45 MHz) and S band
(2498.028 MHz). NavIC coverage area includes India and a region up to 1500 km beyond Indian boundary.
NavIC signals are designed to provide user position accuracy better than 20m (2) and timing accuracy
better than 50ns (2).NavIC SPS signals are interoperable with the other global navigation satellite
system (GNSS) signalsnamely GPS,Glonass,Galileo, and BeiDou
A new civilian signal is being introducedin L1 band(1575.42 MHz).NavIC L1 signal is also interoperable
with the other GNSS signals. All forthcoming (2022-23 onwards) NavIC satellites will broadcast SPS
signals in L1, L5 and S bands.
National and international industry standards:
Signal-in-space interface control document (SIS ICD):
NavIC signal-in-space interface control document provides essential information on the NavIC SPS
signal-in-space to facilitate the use of NavIC SPS signals in PNT applications
L5 & S SIS ICD V1.1 - August 2017
PDF - 2.0 MB
This is draft signal-in-space interface control document (SIS ICD) of NavIC L1
standard positioning service (SPS) signal. The details contained in the draft document,
including the signal structure, are near-final. Only a few parameters could be updated based
on the in-orbit performance of NVS-01. The SIS ICD is expected to be finalised by April
Week number rollover event:
NavIC system time start epoch is 00:00 UT on Sunday August 22nd 1999 (midnight between August 21st and
22nd). The first week number rollover event occurred on April 06 2019. The system time is currently in
the second epoch.
NavIC System Week Number (WN) First Rollover Event
NavIC SPS signal-in-space performance is continuously monitored by a few calibrated receivers
maintained by ISRO. The performance reports are published every quarter as a reference for the
Safety-of-life alert dissemination:
The IRNSS-1A spacecraft located in GSO (Geosynchronous Orbit) with longitude crossing at 55°E is
presently reconfigured as a satellite for disseminating safety-of-life alert messages. These messages
are useful in areas with poor or no terrestrial communication support. Currently this service is used
to provide alerts on cyclones, tsunamis and high sea waves to the fishermen community.
The Signal-in-Space Interface Control Document forsafety-of-life alert disseminationservice provides
the essential information to facilitate the use of IRNSS-1A signal-in-space for development of
receiver and associated applications.
ICD V1.2 – June 2020
PDF - 2.1 MB
The safety-of-life alert dissemination service is being extended to support acknowledgement of
distress signals generated through the Distress Alert Transmitter (DAT).More details about DAT are
available in the SATCOM page. The acknowledgement signal will be generated by the action taking agency
and will boost the confidence of the fishermen in distress. The receiver which has a combination of
DAT and acknowledgement reception capability is called Second Generation DAT (SG-DAT).
The Signal-in-Space Interface Control Document for safety-of-life alert dissemination service,
including the acknowledgement signal of DAT, provides the essential information to facilitate the use
of IRNSS-1A signal-in-space for development of SG-DAT receiver and associated applications.
ICD V1.2 – February 2021
PDF - 1.4 MB
For further information related to navigation service please reach us at:
Satellite Navigation Programme Office, ISRO HQ, AntariskhBhavan, New BEL Road,
Bengaluru, Karnataka, India – 560 094
Telephone: +91-080-2217 2195,