IRNSS Launch and Discussions

SaiK · Post by **SaiK** » 03 Jul 2013 05:45

that apple pic posted by nrao ji on bullock cart shook me up. actually keeping the cost of sat, one would think less riskier options as a program director. if i were to man that decision making, i would dhoti shivered to the core to take bull cart.

we take way too risk, and it is fun, at the same time could be answerable to the future.

if one need to test for vibration, just put the vehicle fixed(nut-bolt-chained-what not) on some regular van and run thru our dirt roads. why the cart?

okay, modify an old car with the top stripped off. btw, vibrations of the kind on space travel is orthogonal to what one can simulate on earth., that too on a cart.

member_23658 · Post by **member_23658** » 03 Jul 2013 05:55

There was a very good reason for putting it on the bullock cart. If i remember correctly it was to prevent static electricity ( or was it electro magnetic ?) from damaging the sat. So they settled on a bullock cart as the safest option available at yhat time. I remember this being discussed in brf a long time ago but maybe wrong.

jamwal · Post by **jamwal** » 03 Jul 2013 09:07

Will this IRNSS system cover our neighbours to help with accurate flowers delivery ?

srin · Post by **srin** » 03 Jul 2013 10:13

A noob question ...

How wide are these orbital slots ? I got one visualization from some site, don't know how correct it is, but looks like the slots are very very wide. From the below pic, it looks like good coverage of Chinese mainland too...

Do you need to book slots for the Geosynchronous satellites too ?

krishnan · Post by **krishnan** » 03 Jul 2013 10:16

jamwal wrote:Will this IRNSS system cover our neighbours to help with accurate flowers delivery ?

we will never known...

tushar_m · Post by **tushar_m** » 03 Jul 2013 10:18

good info on IRNSS

big pic here
http://www.imagenap.com/?di=038F

krishnan · Post by **krishnan** » 03 Jul 2013 10:20

check the circle

tushar_m · Post by **tushar_m** » 03 Jul 2013 11:08

krishnan wrote:check the circle

it covers our old "friend"

PratikDas · Post by **PratikDas** » 03 Jul 2013 11:48

jamwal wrote:Will this IRNSS system cover our neighbours to help with accurate flowers delivery ?

It might just, jamwal ji. Cross-posting ramana ji's post from the Missiles thread:

ramana wrote:Paydirt. The doyens of IGMP have written two papers here!!!!

DSJ May 2013 Issue

papers 1 and 4

Re Paper 1, Its amazing that such senior people do such fundamental papers while still working on program management.
Am very familair with ref 15 in that paper.

From the paper, "ATMOSPHERIC REENTRY DISPERSION CORRECTION ASCENT PHASE GUIDANCE FOR A GENERIC REENTRY VEHICLE" by Avinash Chander and Iyyanki V Murali Krishna, we learn from the abstract that:

In order to achieve minimum miss distance at the target point the atmospheric effects are to be considered during the guided phase and appropriate corrections should be executed, otherwise depending on the reentry flight path angle and ballistic coefficient the errors can be as high as tens of nautical miles. In this paper, the authors develop a novel approach to these vacuum guided launch vehicle problems.The paper elaborates how to calculate a prior the reentry dispersion during the ascent phase guidance and provide guidance corrections such that the terminal conditions are achieved with higher accuracy.

Lalmohan · Post by **Lalmohan** » 03 Jul 2013 11:54

i think this is exciting news - have to say this wasn't on my radar, and comes as a pleasant surprise

Singha · Post by **Singha** » 03 Jul 2013 12:00

they should now make it mandatory that all smartphones sold in india from 2015 onward should have glonass and IRNSS receiver in addition to the GPS.
it will be a small one time expense for the makers to embed such kit....they cannot afford not to play in such a huge market.
this will drive input to any positional app whether for cycling or trekking.

jamwal · Post by **jamwal** » 03 Jul 2013 13:15

It should be optional. Some people like to have privacy

Neela · Post by **Neela** » 03 Jul 2013 13:18

vina wrote:
Wasn't Apple launched from French Kourou? While the Space Program did not have much of a budget i am sure in the 80's a couple of hundreds Rs would not have been a problem to transport the satellite in the good old Matador!!!!
I have seen this photograph many times, indeed myself have also posted it but somehow i doubt if a fully built system (atleast a Satellite)was ever transported in a bullock cart.
Well, Apple got a free ride on the Ariane as it was the first launch on the vehicle ..in fact APPLE stands for Ariane Passenger Payload Eperiment . What my uncle and other ISRO old timers said was, that back then, they didnt have the test facilities to check the vibration and shock characteristics to qualify it for launch (the satellite should survive the shock and vibrations during ascent in the launch vehicle).

So, instead what the dhoti wallahs did was put the satellite on a bullock cart and make it go across the most rutted paths and cross country across the fields and see if it survived to qualify it!

If any of you haven't been on a bullock cart, please take a ride once across a rutted path and the ride will give you an idea..

The first thought that came to my mind when I heard bullock cart was static electricity and electrostatic discharge. Transporting in a vehicle that has metallic parts - these are bound to accumulate charges because of people and materials coming in contact with them. Sensitive electronics in the satellite could offer least resistive paths for discharge and they could get damaged in the process.
I doubt if this has to do with vibration. A vibration test bed can be built with very little money . ( rice mills use a colander type setup to remove stones , husk etc and that is essentially a vibrating platform. )

jamwal · Post by **jamwal** » 03 Jul 2013 13:22

PratikDas wrote:
jamwal wrote:Will this IRNSS system cover our neighbours to help with accurate flowers delivery ?
It might just, jamwal ji. Cross-posting ramana ji's post from the Missiles thread:

ramana wrote:Paydirt. The doyens of IGMP have written two papers here!!!!

DSJ May 2013 Issue

papers 1 and 4

Re Paper 1, Its amazing that such senior people do such fundamental papers while still working on program management.
Am very familair with ref 15 in that paper.
From the paper, "ATMOSPHERIC REENTRY DISPERSION CORRECTION ASCENT PHASE GUIDANCE FOR A GENERIC REENTRY VEHICLE" by Avinash Chander and Iyyanki V Murali Krishna, we learn from the abstract that:

In order to achieve minimum miss distance at the target point the atmospheric effects are to be considered during the guided phase and appropriate corrections should be executed, otherwise depending on the reentry flight path angle and ballistic coefficient the errors can be as high as tens of nautical miles. In this paper, the authors develop a novel approach to these vacuum guided launch vehicle problems.The paper elaborates how to calculate a prior the reentry dispersion during the ascent phase guidance and provide guidance corrections such that the terminal conditions are achieved with higher accuracy.

Pardon my dense brain, but how is trajectory of ascent related to this ? I've tried reading papers, but most of it is greek to me. I thought accuracy of a missile is dependent on factors related to it's descent and re-entry in to atmosphere. Is there anyway to control trajectory by controlling angle of ascent ?

SSridhar · Post by **SSridhar** » 03 Jul 2013 14:25

But, for an extremely accurate delivery of the flowers, the ionospheric effects on signals have to be studied, especially in the equatorial regions, as they vary from location to location and that is what GAGAN does through its ground segments at several locations all over India.

disha · Post by **disha** » 04 Jul 2013 04:57

jamwal wrote:....Pardon my dense brain, but how is trajectory of ascent related to this ? I've tried reading papers, but most of it is greek to me. I thought accuracy of a missile is dependent on factors related to it's descent and re-entry in to atmosphere. Is there anyway to control trajectory by controlling angle of ascent ?

Pardonned

Anyway, read my post on the same qstn., in simple if you do not know where you are., how will you know where you are going?

In short., say you launch a prahaar from road side., the gradients are not perfect. And you would like to know the exact location., in deep jungle you may not find 3 cell towers to triangulate your position and feed it as launch parameters. So prior to launch you definitely need exact location.

Post launch in the ascent phase as well you want to take into account any course correction, since you want to take care of any anomalies introduced due to vibration, ground staff correction., correction in target assignment! - several things and that is where it helps. RLG takes over after that.

member_20317 · Post by **member_20317** » 04 Jul 2013 09:13

I think you guys would like this:

http://en.wikipedia.org/wiki/Q-guidance

The bull snort by Agni also suggests that the job of guiding starts from the launch station itself.

SaiK · Post by **SaiK** » 04 Jul 2013 10:13

I think our lab boys should develop IRNSS chips for smart phones and patent it. big money

merlin · Post by **merlin** » 04 Jul 2013 11:41

disha wrote:In short., say you launch a prahaar from road side., the gradients are not perfect. And you would like to know the exact location., in deep jungle you may not find 3 cell towers to triangulate your position and feed it as launch parameters. So prior to launch you definitely need exact location.

That's what an INS is for, isn't it. The launch vehicle must be having an INS, I assume. One that is initialized when the launcher leaves its depot.

nits · Post by **nits** » 04 Jul 2013 15:13

If our Missiles start using IRNSS; does it mean all of them need to go 2-3 test to ascertain all parameters are working fine and accuracy is maintained \ increased using Desi IRNSS

member_20317 · Post by **member_20317** » 04 Jul 2013 15:24

I dont think so.

The signal can be passive tested on ground and in aircrafts or some flying test beds underslung. What is needed to be checked is whether the receiver receives the signal properly. The trail is all already tested.

SSSalvi · Post by **SSSalvi** » 04 Jul 2013 16:00

srin wrote:A noob question ...

How wide are these orbital slots ? I got one visualization from some site, don't know how correct it is, but looks like the slots are very very wide. From the below pic, it looks like good coverage of Chinese mainland too...

Do you need to book slots for the Geosynchronous satellites too ?

@ Srin,

I don't understand what do you mean by "wide"? For next paragraphs I am using the same reference doc mentioned in the link.

In the simulation diagram there are 3 Geo-Stationary ( i.e. the satellites are placed bang on equator with 0 deg inclination of orbital plane ... thus they appear to be "fixed" throughout day. They are placed at 34 deg, 83 deg and 113.5 deg East longitudes.

Plus there are 4 satellites which are Geosynchronous ( means the period orbit is same as Earth's period of rotation ) but are in orbits which are inclined to Equator at 29 deg. ( unlike 0 deg in previously mentioned 3 satellites ) Therefore for an observer on Earth's surface they appear to move continuously from North to South and back. But they don't travel much in E-W direction ( they appear to be wandering along NS lines centred at 55 deg and 111.5 deg Longitudes ) . This movement results in what is called a ' figure of 8 ' as seen in the diagram there, Also notice that in each orbital plane there are 2 satellites maintained such that when one of the satellites is in Northest portion of orbit its twin satellite is at the Southest end of orbit. ( In technical parlance they are said to be 180 degrees apart in the orbit. )

I hope this explaination helps in understanding the Fig2 and Title figure of the said article.

And Yes, you have to book slots and a few slots are favourite for which there is a big fight to acquire to hold.

SSridhar · Post by **SSridhar** » 04 Jul 2013 16:20

merlin wrote:
disha wrote:In short., say you launch a prahaar from road side., the gradients are not perfect. And you would like to know the exact location., in deep jungle you may not find 3 cell towers to triangulate your position and feed it as launch parameters. So prior to launch you definitely need exact location.
That's what an INS is for, isn't it. The launch vehicle must be having an INS, I assume. One that is initialized when the launcher leaves its depot.

True, but missiles which are mated and ready to launch (as GoI seems to have decided to do) and which provide a second-strike capability might have left the 'depot' a while back and may be roaming around the country side. The INSs tend to acquire error even if they are operational during this sojourn. An exact coordinate is fed into the INS at the time of launch. No chance can be taken with the kind of payload they carry.

Yogi_G · Post by **Yogi_G** » 04 Jul 2013 17:14

I wonder how the IRNSS satelites can be leveraged for our UCAV programmes. If they have the ability for a duplex communication built into them then they can be used to control our UCAVs upto 1500 (much more in reality I believe) KMs away from our borders.

srin · Post by **srin** » 04 Jul 2013 19:35

SSSalvi wrote:
@ Srin,

I don't understand what do you mean by "wide"?

The term 'slot' seems to indicate that the equatorial plane at 36000km altitude is divided into fixed segments - each segment for a satellite. In such a case, what would be the typical separation between two adjacent satellites ?

And Yes, you have to book slots and a few slots are favourite for which there is a big fight to acquire to hold.

Two of the satellites are right over other countries - one in Africa and another over Indonesia (?). Would we be renting such slots from the concerned countries or is it globally controlled by some inter-governmental entity ?

SaiK · Post by **SaiK** » 04 Jul 2013 20:15

do they have or someone has the simulated model/video of IRNSS?

Lalmohan · Post by **Lalmohan** » 04 Jul 2013 20:24

srin - geo stationary orbital slots are indeed rationed by international agreement. you can get the map from the website of the international telecom union

rsingh · Post by **rsingh** » 04 Jul 2013 21:26

Is that Dr Abdul Kalam lost in thoughts ? Humbled by simplicity.

SSSalvi · Post by **SSSalvi** » 04 Jul 2013 21:45

@Srin

Firstly the Space above a country does not belong it. Space is an international property controlled ( not owned ) by regulatory bodies like ITU etc.

There are no fixed distance slots. The distance between two adjacent satellites is primarily decided by mutual interference due to communication systems of each satellite. Up and Down signals of one satellite should not cause problem to adjacent satellite's communication.
A few techniques like polarization diversity, different frequencies, Encoding etc are used so that even if the satellites in the vicinity of each other they can work without interfering with each other.

A good compilation various satellite characteristics is available in lyngsat.com

gkriish · Post by **gkriish** » 05 Jul 2013 05:45

rsingh wrote:

Is that Dr Abdul Kalam lost in thoughts ? Humbled by simplicity.

Thanks For Posting this Pic Mr Singh this shows how humble we begin and now where we are in Rocket tech..... and launch some Kick A** Rockets and satellite well we are launching to Mars this year so......... Thank you again......

srin · Post by **srin** » 05 Jul 2013 08:33

@SSSalvi sir, @lalmohan, thank you very much for enlightening an ignorant jingo

pushkar.bhat · Post by **pushkar.bhat** » 05 Jul 2013 09:43

Vipul wrote:Against an intended perigee (nearest point to Earth) of 280 kilometers, apogee (farthest point from the Earth) of about 20,600 kilometers with an inclination of 18 degrees with respect to the equator the satellite was launched into a sub Geosynchronous Transfer Orbit with a 284 km perigee and 20,650 km apogee with an inclination of 17.86 degree with respect to the equatorial plane.

Love this

.. I am sure it gave some of our "friends" a scare of their life.

SaiK · Post by **SaiK** » 05 Jul 2013 09:53

^

The navigational system would provide two types of services --Standard Positioning Service, which is provided to all the users and Restricted Service, which is an encrypted service provided only to the authorised users. IRNSS applications include mapping and geodetic data capture, precise timing, visual and voice navigation for drivers, integration with mobile phones and terrestrial, aerial and marine navigation, terrestrial navigation aid for hikers and travellers.

I am waiting for the device.

merlin · Post by **merlin** » 05 Jul 2013 10:37

SSridhar wrote:
merlin wrote: That's what an INS is for, isn't it. The launch vehicle must be having an INS, I assume. One that is initialized when the launcher leaves its depot.
True, but missiles which are mated and ready to launch (as GoI seems to have decided to do) and which provide a second-strike capability might have left the 'depot' a while back and may be roaming around the country side. The INSs tend to acquire error even if they are operational during this sojourn. An exact coordinate is fed into the INS at the time of launch. No chance can be taken with the kind of payload they carry.

Oh, yeah

Forgot about the decision to mate warheads even for land based strategic missiles. I think the only difference will be that the launchers won't "patrol" all the time like the Arihant class will (once fully operational in numbers) but will only do so in times of high tension. And patrol times will be a few weeks at least which will lead to INS drift even for RLGs and FOGs.

Gagan · Post by **Gagan** » 06 Jul 2013 05:19

Way to go ISRO, stupendous launch.

But I think everyone is being overoptimistic about the IRNSS signals for the common man's use. Given GoI's baboozes' shenanigans / tendency for over-secrecy, I am 400% expecting this IRNSS vs GPS battle to end like the Bhuvan vs Google Earth battle.

Singha · Post by **Singha** » 06 Jul 2013 08:56

+1 to that. as I mentioned the only way to make sure people develop apps and things for it is make it mandatory for all smartphones sold in india beyond a certain date to carry the IRNSS signal. india is now the worlds 2nd or 3rd largest smartphone market.

GOI simply has no clue how to leverage the market.

SSSalvi · Post by **SSSalvi** » 06 Jul 2013 09:52

There are a lot of expectations from IRNSS.. but we may have to wait till evaluation of this satellite is over and modified ( if necessary ) versions of other satellites are launched because for triangulation of distances just one satellite is not sufficient.

Indian system can't be tested in conjunction with existing GPS because the total structures of both the systems are different.

US GPS has satellites at 20,200 kms altitude ( with 12 hrs orbit ) and not geostationary as envisaged in IRNSS. The GPS satellites are not Earth Synchronous but are synchronised with stars. It follows that the geodesic software relations with IRNSS has to be totally evolved from scratch and both are not interchangeable.

IRNSS receivers will be useless as soon as one leaves its footprint ( basically Indian region ) because the satellites are available only over this region.

suryag · Post by **suryag** » 06 Jul 2013 10:00

SSS and singha garus how will smartphones be benefitted if they have an IRNSS receiver, in other words what does IRNSS provide for smartphones over India which existing GPS/GLONASS systems dont provide?

Merril · Post by **Merril** » 06 Jul 2013 10:08

Singha wrote:+1 to that. as I mentioned the only way to make sure people develop apps and things for it is make it mandatory for all smartphones sold in india beyond a certain date to carry the IRNSS signal. india is now the worlds 2nd or 3rd largest smartphone market.

GOI simply has no clue how to leverage the market.

Singhaji,

How does the use of IRNSS over GPS benefit the aam Abdul in India? I mean other than the fact that that it Indian, is there any specific advantage?

The only thing that I can think of is that the the phone/device manufacturers have to pay some royalty to the US gov for the usage of the signals. However due to the sheer number of devices that use GPS nowadays, I don't suppose that's the situation.

Edit: I see suryag has already asked a similar question.

PratikDas · Post by **PratikDas** » 06 Jul 2013 10:50

suryag wrote:SSS and singha garus how will smartphones be benefitted if they have an IRNSS receiver, in other words what does IRNSS provide for smartphones over India which existing GPS/GLONASS systems dont provide?

For one, time to first fix (TTFF) should be considerably shorter since there are a limited number of satellites and in geosynchronous orbit as well.