How Kargil spurred India to design own GPS

[Skull and Bones]

Sooner or later, global deployment should be the point. A fourth alternative for a global positioning system.

 

[AugenBlick]

No they are not. I have 5 gps with me, 2 of them just antennas... Most cellphones have them. So, even if it is encrypted, key is widely available with public...

The Military signals are encrypted, which are highly accurate.
GPS signals - Wikipedia, the free encyclopedia

To prevent unauthorized users from using or potentially interfering with the military signal through a process called spoofing, it was decided to encrypt the P-code. To that end the P-code was modulated with the W-code, a special encryption sequence, to generate the Y-code. The Y-code is what the satellites have been transmitting since the anti-spoofing module was set to the "on" state. The encrypted signal is referred to as the P(Y)-code.

 

[NEPALESE GURKHA]

But that means entire region would be without GPS. Plus, US govt needs to know that it is being used for war... If we wanted GPS (I hardly think IA/IAF had any use for it during Kargil), we could have used this until US turned them off for a whole month (Which I don't think it would do).. Only thing that could have happen is India might have wanted military grade precision.....

i m not saying it for kargil, what i say is in future conflict US may turned it off coz they have bilateral relation with pak military eastiblishment too

 

[Thirdfront]

The Military signals are encrypted, which are highly accurate.
GPS signals - Wikipedia, the free encyclopedia

I know military signal are encrypted, but ISRO's military signals are worst than GPS free signals. GPS free signals are 7.8 m accurate (95% confidence) where as India's 10 m (for military)... That is what I am confuse about..

i m not saying it for kargil, what i say is in future conflict US may turned it off coz they have bilateral relation with pak military eastiblishment too

I agree on that point, better to have your own systems. I was referring to the article..

 

[The Deterrent]

I know military signal are encrypted, but ISRO's military signals are worst than GPS free signals. GPS free signals are 7.8 m accurate (95% confidence) where as India's 10 m (for military)... That is what I am confuse about..

Military and non-military GPS receivers/signals work differently. There is an altitude and speed restriction on the non-military ones, so while they are pretty accurate too, they won't work for anything faster or higher than a passenger jet (or say, they won't work for a ballistic missile/guided bombs etc). Moreover the military ones are much more accurate and stable.

But there are work-arounds (i.e. jugaad) to remove these restrictions and also increase the performance of non-military receivers. The Chinese are pretty much into decoding the US GPS signal, similarly accuracy can be increased by augmentation with a fixed ground station.

 

[Vinod2070]

I know military signal are encrypted, but ISRO's military signals are worst than GPS free signals. GPS free signals are 7.8 m accurate (95% confidence) where as India's 10 m (for military)... That is what I am confuse about..

I believe accuracy will depend on the number of satellites available to cover a particular spot.

Still if GPS military signals can have an accuracy of much less than a meter, not sure why the Indian system should have an accuracy of 10 m.

Is it possible that the actual accuracy of the restricted system is much better and not being made public?

 

[Thirdfront]

Military and non-military GPS receivers/signals work differently. There is an altitude and speed restriction on the non-military ones, so while they are pretty accurate too, they won't work for anything faster or higher than a passenger jet (or say, they won't work for a ballistic missile/guided bombs etc). Moreover the military ones are much more accurate and stable.

But there are work-arounds (i.e. jugaad) to remove these restrictions and also increase the performance of non-military receivers. The Chinese are pretty much into decoding the US GPS signal, similarly accuracy can be increased by augmentation with a fixed ground station.

This is not correct. US has restrictions on the receivers made in US and exported outside US (on speed and altitude). But the receivers made outside US have no such restriction. For military grade signals, only way to use them w/o US approval is to break encryption and I doubt anybody have done that.

 

[Contrarian]

I know military signal are encrypted, but ISRO's military signals are worst than GPS free signals. GPS free signals are 7.8 m accurate (95% confidence) where as India's 10 m (for military)... That is what I am confuse about..

As is the norm in Indian Governmental agencies, the ranges are simply said to be <10m for military. It could be 1m or 2m or 9.8m.

Prior experience of DRDO and the new found (relative) secrecy suggests that the accuracy would be much lower and ISRO is ambiguous deliberately.

But there are work-arounds (i.e. jugaad) to remove these restrictions and also increase the performance of non-military receivers. The Chinese are pretty much into decoding the US GPS signal, similarly accuracy can be increased by augmentation with a fixed ground station.

We do both.
1. India has already built and commissioned the first phase of SBAS(Space Based Augmentation System) for boosting accuracy of GPS. If I recall correctly, we are the 4th individual nation in the world to have done this - if you count Europe as one.

2. We also have unrestricted access to mil grade signals from GLONASS as we are a partner in the GLONASS system.

Our new missiles are now mandated to make and incorporate tech which would allow shifting from Navstar GPS to GLONASS to IRNSS(Indian) navigation system mid flight. This happened after the BrahMos flight deviated because US switched off secure GPS for a while without announcement.

 

[timetravel]

I believe accuracy will depend on the number of satellites available to cover a particular spot.

Still if GPS military signals can have an accuracy of much less than a meter, not sure why the Indian system should have an accuracy of 10 m.

Is it possible that the actual accuracy of the restricted system is much better and not being made public?

pretty much true... India now can do anything in space that US can. The issue is not technology but resources.

given sufficient funds, ISRO can achieve everything NASA has done (off course not immediately but in due time).

I am sure the precision of the ISRO system for military would be as good as that of US systems.

 

[Sourya Kharb]

Great Work India
We have to less depend on other countries

 

[Aarush]

building your own capabilities is good, why to depend on others no matter how close RUSSIA is.

welcome in forum..bro...

 

[Thirdfront]

I believe accuracy will depend on the number of satellites available to cover a particular spot.

Still if GPS military signals can have an accuracy of much less than a meter, not sure why the Indian system should have an accuracy of 10 m.

Is it possible that the actual accuracy of the restricted system is much better and not being made public?

Accuracy depends on lot of factors, including precision time synchronization between the sats and ground, weather, number of sats in range etc. It is possible that military grade signals have higher precision and not made public, but can think why would anybody do that. I would imagine people exaggerating the accuracy though...

As is the norm in Indian Governmental agencies, the ranges are simply said to be <10m for military. It could be 1m or 2m or 9.8m.

Prior experience of DRDO and the new found (relative) secrecy suggests that the accuracy would be much lower and ISRO is ambiguous deliberately.


We do both.
1. India has already built and commissioned the first phase of SBAS(Space Based Augmentation System) for boosting accuracy of GPS. If I recall correctly, we are the 4th individual nation in the world to have done this - if you count Europe as one.

2. We also have unrestricted access to mil grade signals from GLONASS as we are a partner in the GLONASS system.

Our new missiles are now mandated to make and incorporate tech which would allow shifting from Navstar GPS to GLONASS to IRNSS(Indian) navigation system mid flight. This happened after the BrahMos flight deviated because US switched off secure GPS for a while without announcement.

Till the sats are in place it would be just a design spec. Let us wait and watch..

 

[Vinod2070]

Accuracy depends on lot of factors, including precision time synchronization between the sats and ground, weather, number of sats in range etc. It is possible that military grade signals have higher precision and not made public, but can think why would anybody do that. I would imagine people exaggerating the accuracy though...

Well, you never declare all your military capabilities.

The sats are carrying atomic clocks so accuracy of clock can't be a limiting issues.

I think theoretically they can achieve a sub meter accuracy on par with GPS. Even accounting for some real life issues, it can't be as low as 10 m.

 

[OrionHunter]

No they are not. I have 5 gps with me, 2 of them just antennas... Most cellphones have them. So, even if it is encrypted, key is widely available with public...

You have commercial GPS. What we're talking of is military applications where the signals will be encrypted.

 

[Thirdfront]

Well, you never declare all your military capabilities.

The sats are carrying atomic clocks so accuracy of clock can't be a limiting issues.

I think theoretically they can achieve a sub meter accuracy on par with GPS. Even accounting for some real life issues, it can't be as low as 10 m.

You may be amazed know that due to velocity and height of the sats, atomic clocks will not run at same speed. They need to account for time variation in space constantly. Theory of relativity in action. I am sure our accuracy will be less than GPS if everything was developed in house...