Last satellite in the Indian Regional Navigation Satellite System launched

I didn't understand this. How would the GPS system allow the US to know the location of Pakistani soldiers? GPS satellites only transmit and GPS receivers only receive - there is no return path that would disclose the location. What am I missing?

Case of typical uninformed journalism. The basic use would be independent and reliable GPS guided munition.

> India took a firm decision on IRNSS in 1999 after the US government refused to share GPS data

Given India's rising position in the world economically (they'll have the fifth largest economy in two years or so) and militarily, they'd have been crazy to not go forward with their own system regardless. That's particularly the case given India has a very complex position among all the powers, from the US to the EU to Russia to China. They're far less blatantly aligned one direction or another than the rest.

Their general geo-political neighborhood presents wild security considerations. To be a fully independent power in the coming decades, they'll want to gradually acquire their own capabilities at most things.

Where exactly does it say this the reason to start working on the "system" ? Also what do you mean by "work on the system" ? Reason for who to start working on the system ?

The Indian government is probably also concerned that if the USA ever gets into a shooting war with China or Russia, the GPS constellation could be destroyed by anti-satellite weapons (or at least rendered temporarily inoperable by other means).

If you build your missiles to work using gps (as another poster pointed out), then you also want those to work if the US decides to not let you use the gps system.

How can you tell which nav systems your phone can see?

These are essential national security assets, used for military purposes, and which a hostile (or even neutral) owner could turn off in case of war. The civilian use-case is a handy side benefit.

> ...my phone detected one of those satellites earlier about 2-3 weeks ago. Interesting, especially considering I'm nowhere near Japan.

Could be an error, but you could just be in Australia or just about anywhere on the Eastern hemisphere. The orbits are geosynchronous and thus very high.

https://en.wikipedia.org/wiki/Quasi-Zenith_Satellite_System#...

QZSS has been in test phase since 2010, and has had a full constellation of 4 satellites since last year.

I don't think IRNSS covers regions outside South Asia.

> Do missile systems also lose track of their position midway through a flight like our phones?

Civilian grade GPS receivers are intentionally crippled to stop working above some altitude/speed limits.

EDIT: It seems that the COCOM limits apply only after "1,900 km/h at an altitude higher than 18,000 m".

However, looking at the ublox receivers as an example, they have to be explicitly configured to operate at aircraft-level speeds, which smartphones likely aren't.

Missile have their own very complex on-board guidance systems that don't require GPS at all. Newer missiles might use GPS as an extra layer of calibration, but I doubt they rely on it and most likely discard it if it's way off (otherwise GPS interference could potentially jam a missile).

The main things that cause loss of GPS 'lock' are the satellite signals being blocked (buildings, terrain, people, etc in the way), and multipath (signals being reflected off buildings, terrain, etc). A munition a few thousand feet above the ground has none of those things.

(There's also 'GPS jamming', which is totally a thing in war, but that's not really 'like our phones', generally.)

As other posts have mentioned, though, GPS is simply one input into weapons systems, not the input into weapons systems.

They not only have better receivers than in our phones, they have an entirely separate signal they can use- P-code (https://en.wikipedia.org/wiki/GPS_signals#Precision_code).

It's encrypted, so it's not for civilian use, and the ability to look at two signals of different frequency at the same time means that they have been able to have much more robust GPS than civilians for awhile.

Ballistic missiles use stars mid-flight and inertial guidance system during the terminal phase. Cruise missiles follow terrain.

Many of those systems were designed before GPS became operational, but even now relying on GPS is not particularly prudent.

Airplanes are big metal tubes that can block GPS signals, that's probably the problem you're having.

War is the mother of all inventions.

Technology tends to be value-neutral. The application of technology could be for evil or for good. To claim that the primary purpose of the Indian Regional Navigation Satellite System (NAVIC) is for belligerent activities is to claim knowledge of the intentions of the Indian government at the time of the system's creation.

Couldn't it be just as likely or more likely that multiple positive and negative rationales were in play at the time?

  - reduced dependency on the US
  - chance to learn something for oneself
  - give boost to the Indian aerospace fields
  - home-grown navigational abilities for war but also for civilian use
  - pride, wanting to be seen as a global tech leader
  - any other number of things?

I think it is amazing that we now have not one (US) but five (US, EU, CN, IN, RU) navigational satellite systems, two of which (US, RU) are globally operational and two more will be (EU, CN) by 2020. What interesting times we live in.

Civilization is having the gun and choosing not to use it. Not bothering with the gun, singing kumbayah and depending on human goodwill is never going to work.

Human history shows there are competing interests who are willing to kill to get their way. Those lulled into a sense of complacency by fantasy narratives about the how the world works learn the hard way.

See the list of recent victims in the middle east starting from Iraq, Libya and now Syria. Tens to hundreds of thousands killed, families destroyed, infrastructure, education, healthcare destroyed and countries sent back decades if not hundred years in service of human greed.

And 50 years later commentators will dismiss these 'third world' countries as utter failures and insinuate some deficiency without any context of history. You can debate for ever but the man with the biggest gun gets the last word.

Remember, the internet was a result of DARPA's work.

Not war, but self-preservation.

Historical fact: India has fought 5 wars since 1947, but was never the aggressor. India, or any country for that matter, doesn't choose its neighbors.

As good but works only in the Indian subcontinent and its neighbourhood.