India's IRNSS Successfully Demonstrates Independent 3D Position Determination For the First Time

[Chanakya's_Chant]

Comparing Indian costs to European/American costs isn't really fair. Indian salaries are much lower, India's PPP multiplier is huge.

And so is the cost of living.

 

[Chanakya's_Chant]

 

[anant_s]

Any idea about GPS M-code's accuracy?

GPS.gov: GPS Accuracy

 

[Brahma Bull]

No comments from the PIKAS ?
I urge the senior Indian members to tag some of Pika trolls in such threads too...

 

[sathya]

No comments from the PIKAS ?
I urge the senior Indian members to tag some of Pika trolls in such threads too...

Don't you like how the thread is going ?

Why tag trolls, instead informed members can make the discussion more interesting ,.

 

[Chanakya's_Chant]

GPS.gov: GPS Accuracy

Very little has been published about this new, restricted code that is the M-code - no accuracy figure

Interestingly the accuracy of the GPS signal in space is actually the same for both the civilian GPS service (SPS) and the military GPS service (PPS). However, SPS broadcasts on one frequency, while PPS uses two. This means military users can perform ionospheric correction, a technique that reduces radio degradation caused by the Earth's atmosphere. With less degradation, PPS provides better accuracy than the basic SPS.

New receivers and no supporting apps (ala Google Earth).

IRNSS will support Bhuvan.

 

[acetophenol]

Good Job!

 

[utraash]

Chanakya buddy I must say your threads are very informative n good for layman like me...... Keep it up buddy.......

 

[cloud_9]

Accuracy is low?
Or is it just a TD?
New receivers and no supporting apps (ala Google Earth). Why would anyone shift from GPS to IRNSS apart from Indian military maybe. Even then GPS's civilian version has better accuracy (10m) than this.

GPS has also started beaming L5 signal for ARNS use and there are products available in the market for professional use .Not sure what software applications have to do with signal frequencies, as they all support a set of standard data formats.

Furthermore, it has been observed that the performance of IRNSS L5-signal is comparable to that of L5/E5a-signals of other systems.

Assessing the IRNSS L5-signal in combination with GPS, Galileo,and QZSS L5/E5a-signals for positioning and navigation

 

[Super Commando Dhruva]

• We had 1 Bromos failure a year back, reason Cleaver FOX "USA" was turning off GPS signals Just for this missile so can we use this for Data link and for missile guidance ?

 

[Chanakya's_Chant]

• We had 1 Bromos failure a year back, reason Cleaver FOX "USA" was turning off GPS signals Just for this missile so can we use this for Data link and for missile guidance ?

It was in 2009 that the BrahMos test failed as due to security reasons, the US had switched off GPS signals during Obama's swearing-in ceremony - as a result of which it was decided to switch over to GLONASS and later BrahMos variants has been upgraded with advanced guidance algorithm featuring G3OM (GPS, GLONASS, GAGAN on a Module) receiver - Through G3OM receiver, the missile could take target acquisition from American GPS, Russian GLONASS and India’s GAGAN system at one go. Combined with inertial navigation system (INS), a G3OM receiver provides very high accuracies even without a seeker. When tested - it was the first time that any missile with all two satellite navigation systems and one SBAS was ever tested.

 

[Chanakya's_Chant]

@21 Dec 2012 @anant_s - Here's an article on combining IRNSS & GAGAN - ISRO will eventually do the same in the long run.

Combining GAGAN with IRNSS
APR 2013 | NO COMMENT
Vyasaraj Guru Rao, Gerard Lachapelle

This research explored the possibility of combining the GAGAN (SBAS) with IRNSS. In addition,
with new messages included, the proposed SBAS can also transmit the corrections for IRNSS

Vyasaraj Guru Rao
University of Calgary,
Canada & Accord
Software & Systems Pvt Ltd,
Bangalore, India

Gérard Lachapelle
Professor of Geomatics Engineering,
University of Calgary,
Canada

The Indian Spa ce Research Organisation (ISRO) is in the process of deploying the Indian Regional Navigation System (IRNSS), a dual frequency service system. Another contribution by ISRO in the area of Navigation system is GPS Aided GEO Augmented Navigation (GAGAN), an augmentation system. Till date, to the best of authors’ knowledge there is no work that has explored the potential synergy between IRNSS and GAGAN. An article in the previous edition (Coordinates Feb 2011) showcased some research work where new locations were suggested for IRNSS satellites to enhance its regional coverage. Based on the proposed locations, this research presents an engineering synergy between IRNSS and GAGAN and highlights its distinctive merits.

To begin with, a brief introduction to GAGAN and IRNSS is presented from a signal’s perspective. Following this, the optimization criterion used in this research is deduced. The main factors affecting optimization are elaborated in detail with the optimal constellation deduced. Finally, the merits of the proposed constellation are discussed in detail.

GAGAN
The void SBAS foot-print between EGNOS (Europe) and MSAS (Japan) is established by GAGAN. The following section describes the control and space segment components that make GAGAN operational.

The GPS satellites visible over the Indian subcontinent are continuously tracked at several monitoring stations. The stations are equipped with state of the art reference (survey grade) receivers that provide precise estimates of pseudoranges, carrier phase measurements and time information based on dual frequency. The stations also have the antenna located at a surveyed location. In addition, these receivers provide estimates of satellite related anomalies (for example, Signal Quality Monitoring (SQM)), if any. With these inputs and traits, measurements are formulated. Further, the integrity stations are spread across the Indian land mass (to obtain the ionosphere data for modelling), which relay the data to the master control station located in Bangalore. Based on the collated data from various stations, the messages are generated as per SiS requirements of SBAS (DO- 229D 2006). These structured messages are uplinked in C-band to the GAGAN satellites as shown in Figure 1 a). ( (GAGAN Architecture 2012), (Ganeshan 2012)).

F igure 1: Control and space segment architectures of a) GAGAN b) IRNSS.​

GAGAN will have three geostationary satellites when fully operational with the signal footprint spanning over the Indian subcontinent (Kibe & Gowrishankar 2008). Points noteworthy of this signal are:
• transmitted in L1 band at 1575.42 MHz

• transmitted at -160 dBW, similar to GPS L1 C/A

• codes used are from the GPS L1 C/A family

• basic data rate is 250 Hz

• rate ½ 7 bit Viterbi encoding is employed on data bits and thus effective symbol rate is 500 sps.

• GPS receiver accuracies achievable over the Indian land mass with this signal will be similar to that achieved over the US with or without WAAS.

Figure 2: GAGAN (GEO-3 position assumed) and IRNSS geostationary satellites.​

From the above points, it is clear that the signal (data) is transmitted fi ve times higher than the GPS L1 C/A (ISGPS- 200E 2010) but its power has not been increased. This can be attributed to the following reasons:
• First, to achieve similar performance to L1 C/A (w.r.t measurement accuracies), 12 dB additional power would be required. This would act as in-band jammer and lift the noise fl oor of the GPS L1 channels (Parkinson & Spilker 1996).

F igure 3: Satellite availability with current IRNSS and proposed IRNSS constellation​

• Second, to accommodate the above requirement, the absolute power required would be -148 dBW, which violates the guidelines for space based signal transmission (Singh et al 2008). Thus, with -160 dBW the ranging measurement performed on SBAS will be relatively inferior to GPS L1 (Parkinson & Spilker 1996). This not being a system objective, SBAS focusses on providing integrity messages and can effectively be interpreted as a data channel.

IRNSS
As a second initiative in the space based navigation, IRNSS is ISRO’s other contribution with an objective to provide independent regional navigation to cover its territorial footprint and slightly beyond. The system is expected to be operational by the end of 2015 (Bhaskaranarayana 2008). The system of space and control segment for IRNSS is as shown in Figure 1 b) (IRNSS Architecture 2012). The top level details of the control and space segments are as follows:
Similar to the GAGAN control segment, IRNSS Range Integrity Monitoring Stations (IRIMS) will be deployed at several places spread across the Indian subcontinent. These stations will be equipped with high end receivers which will provide all relevant information about the satellites. With the signal transmission from the fi rst satellite, these receivers will perform measurements and collect the NAV data. The data will be relayed to the master control station located in Bangalore. Based on this data, batch (typically) processing will be performed to generate the Keplerian parameters of all the satellites, the clock correction terms and the secondary NAV data information. Unlike GAGAN, this is a complex activity that determines the overall system accuracy (User Equivalent Range Error (UERE) (Rao et al 2011). The data generated is uplinked to IRNSS satellites.

The space segment will have a total of seven satellites, four in geostationary and three in geosynchronous orbits (Bhaskaranarayana 2008). Some features about IRNSS signals available from open sources are:
• The IRNSS L5 and S1 will transmit signals for civilian/restricted operations (Kibe & Gowrishankar 2008).

• There will be a total of seven satellites, three in geostationary and four in geosynchronous orbit as shown in Figure 1 b).

Optimization
From a regional perspective, it is clear from Figure 1 that there will be six payloads on six geostationary (3 each of IRNSS and GAGAN) satellites serving the navigation needs centered over the Indian subcontinent in the near future. From a system perspective, an obvious engineering optimization w.r.t the number of satellites is evident from Figure 2 constrained by the individual specifi cations of each system. Optimization w.r.t reduction in the number of satellites being the objective, the following section proposes to reduce the satellite count, yet fully meet the IRNSS and GAGAN functionalities and fi nally deduce a simple third frequency option for IRNSS.

To begin with, the assumptions made for the optimization are presented in Table 1. These assumptions are for the signals (GAGAN, IRNSS, and (GAGAN+IRNSS) w.r.t GNSS) over the Indian subcontinent. The attributes enumerated in the assumptions are backward compatible – which is applicable when a new system in proposed with a system already operational, interoperable – that is mutual existence of two systems and Frequency fi ling – which is a pre-requisite before a signal is transmitted from the satellite.

With the above assumptions, it is evident that the systems can be integrated without too many external issues and only constrained by the resources on the satellites. Based on the research work published in (Co-ordinates Feb 2013), the constellation as listed in Table 2 is proposed for IRNSS and GAGAN.

Advantages
The merits of IRNSS on GAGAN are explained as follows:

Availability

Availability from the proposed IRNSS is drastically enhanced (Coordinates Feb 2013). In addition, from Figure 3, it is very clear that the GAGAN coverage area is signifi cantly enhanced, which is the polygon b. This is nearly a 60% increase in the coverage of GAGAN service volume

SBAS & high dynamics

As mentioned in the earlier section, with the success of GPS and the need for correction/integrity, the SBAS program emerged. A similar proposition might arise in future for IRNSS. With few additional messages exclusively for IRNSS, GAGAN can be modifi ed to account for the IRNSS’s SBAS corrections as well. Through textual data (for example, some SBAS messages for IRNSS can be supported and, due to the inherent data rate limitations (50 Hz) and the need for some of the messages to be fast (for example, fast correction messages of SBAS), dedicated medium is required. This can be easily handled by additional messages onboard GAGAN (for example, GLONASS SBAS messages transmitted in EGNOS in addition to GPS (EGNOS 2011).

Fi gure 4: Proposed IRNSS+GAGAN constellation.​

Higher user dynamics require wider Doppler search ranges. This coupled with high data rates (500 sps) puts a constraint (sensitivity) w.r.t SBAS acquisition in standalone mode (for example, no estimates of position, velocity, almanac or time). With the integrated proposal, IRNSS satellites when tracked in L5/S1 can directly assist L1 (SBAS) and thus improve performance drastically w.r.t acquisition in high dynamics.

Satellite count

An obvious advantage with this approach is that GAGAN satellites with IRNSS frequencies will eliminate three IRNSS geostationary satellites. Unlike GAGAN, IRNSS are dedicated navigational satellites. Assuming a pessimistic estimate of 100 million USD/satellite including launch, a signifi cant reduction in the cost is achieved (300 million USD in all) with the proposed integrated architecture. At the same time, the specifi cations of both systems are effectively met.



Control segment

A synergized network can be established to effectively have a common control and monitoring station for both IRNSS and GAGAN ensuring all system parameters are obtained as required by individual systems and collated at a common master control station. With this, the operational overheads are drastically reduced resulting in the architecture shown in Figure 4.

Third frequency on IRNSS

With the geosynchronous satellites always visible over Indian subcontinent, the third frequency (L1) (when adapted on GSO’s) can be used for safety of life applications as in GALILEO E6 (Galileo 2008). With the advantage that these satellites carry the L5/S1 signals and assuming collaborative tracking (Borio 2008), the data rate can effec`tively be increased to 1 KHz on these channels without increasing power.

Conclusion
Till date the navigation and the augmentation system (satellites) have been different in every GNSS. This research explored the possibility of combining the GAGAN (SBAS) with IRNSS. In addition, with new messages included, the proposed SBAS can also transmit the corrections for IRNSS. From a regional perspective, this proposal provides the optimal coverage, more advantages (for example, availability, reduced satellite count, SBAS of IRNSS) is achieved with less (without additional) satellites.

Acknowledgements
The first author would like to thank the management of Accord Software & Systems Pvt Ltd India for partially supporting his doctoral studies

References
V G Rao and G Lachapelle (2013) “Want more for Less”, Co-ordinates Magzine, Feb 2013, 4 pages

Bhaskaranarayana (2008) Indian IRNSS & GAGAN, Presentation to COSPAR Meeting, Montreal. July 15, 2008

DO-229D (2006) Minimum Operational Performance Standards for GPS / WAAS System Airborne Equipment, Sc-159

EG NOS (2011) EGNOS Safety of Life Service Definition Document

Galileo (2008) Galileo Open Service Signal In Space Interface Control Document, OS SIS ICD, Draft I, European Space Agency / European GNSS Supervisory Authority, Index of / gsa.europa.eu/go/galileo/os-sis-icd

IS-GPS-200E (2010) Navstar GPS Space Segment/Navigation User Interfaces, Interface Specification

Kibe, S, V and Gowrishankar. D, APRSAF -15: Space for Sustainable Development, December 10th 2008, Vietnam

Parkinson, B.W. and J.J. Spilker (1996) Global Positioning System: Theory and Applications, American Institute of Aeronautics and Astronautics Inc, Cambridge, Massachusetts

Rao, V. G., G. Lachapelle, and S.B. Vijaykumar (2011) “Analysis of IRNSS over Indian Sub-continent,” in Proceedings of the International Technical Meeting, , San Diego, The Institute of Navigation, 13 pages

Singh, A.K., A.K. Sisodia, and V. Garg (2008) “Modulation Designs For Indian Regional Navigation Satellite Systems,” in International Aeronautical Federation

Ganeshan A S, GAGAN: Status and Update, Coordinates VOL VIII, Issue 9 September 2012

Source:- Coordinates : A resource on positioning, navigation and beyond » Blog Archive » Combining GAGAN with IRNSS

 

[kṣamā]

Damn this is so coool

 

[anant_s]

F igure 3: Satellite availability with current IRNSS and proposed IRNSS constellation

Although i couldn't read properly with respect to the index below, it looks like IRNSS would cover a large parts of entire sub-continent, middle east and almost all of ASEAN. & here i believe lies a good business opportunity of providing cheaper and high reliability positioning and mapping services.
The article mentions about relatively low cost of Satellite systems (sometime inherently advantageous with Indian Satellites) and that could create a niche market for itself.
Also we are covering almost all of Indian Ocean, Gulf of Aden and other shipping lanes. this should become a major advantage, not only for Navy patrolling the region but also for maritime trade.
Looks really promising enterprise IMHO.

 

[IND151]

No comments from the PIKAS ?
I urge the senior Indian members to tag some of Pika trolls in such threads too...

Are you referring to trolls from land to our west?