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Chinese ASAT vs US ASAT

You're confusing JDAM with Laser JDAM.
And you should learn to read. The man said...

Literally, nobody ever use GPS designation and almost all uses of JDAM are using Laser Designation.
The 'almost all' mean he know there is a difference between laser designated and simply GPS-aided.

Just like the rest of the Chinese members here, you are good at copy/paste actions, but never at explaining the foundational principles of how things work. Still...Let us see how much you really understand of what you copy/paste about this subject...

Laser guided/designated free fall bombs predate GPS-assistance. The initials 'JDAM' has nothing to do with the FUNCTIONS of a weapon but merely an operational and logistical label. No different than High Mobility Multipurpose Wheeled Vehicle (HMMWV).

Question: Why is GPS assistance needed?
 
And you should learn to read. The man said...


The 'almost all' mean he know there is a difference between laser designated and simply GPS-aided.

Just like the rest of the Chinese members here, you are good at copy/paste actions, but never at explaining the foundational principles of how things work. Still...Let us see how much you really understand of what you copy/paste about this subject...

Laser guided/designated free fall bombs predate GPS-assistance. The initials 'JDAM' has nothing to do with the FUNCTIONS of a weapon but merely an operational and logistical label. No different than High Mobility Multipurpose Wheeled Vehicle (HMMWV).

Question: Why is GPS assistance needed?

This guys response seems to amaze me a lot.

lol, last time I check. almost all JDAM were upgraded to LJDAM back in 2000s. original GPS/INS JDAM are for fixed target strike (Also know as hard target) those target that do not move. Later version of JDAM were upgraded with tracker device and issued with a Laser Det. Of course we will have some un-upgraded JDAM in stock, but we hardly use them anymore. That was so 90s technology.

according to this Joint Direct Attack Munition - Wikipedia, the free encyclopedia

Experience during Operation Enduring Freedom and Operation Iraqi Freedom led US air power planners to seek additional capabilities in one package, resulting in ongoing program upgrades to place a precision terminal guidance seeker in the JDAM kit.[14] The Laser JDAM (LJDAM), as this upgrade is known, adds a laser seeker to the nose of a JDAM equipped bomb, giving the ability to engage moving targets to the JDAM

Of course, this maybe too advance for a Chinese member to digest, as they probably do not have the script for it yet :) Seeing that according to j20blackdragon, China only have smart munitions back in December 2012. They may still have people running around with a GPS receiver trying to chase a moving target so it can be hit by a GPS guided bomb LOL :lol:
 
Milstar is a constellation of communications satellites. What does this have to do with weapons guidance, JDAM, or anything else we're currently discussing? You can have zero communications satellites in space and JDAM will still work fine as long as GPS is functioning.

I was making a point that there are more than military GPS Satellite exist. I NEVER did say MILSTAR guided the bomb themselves. Please do not twisted what I said.

You're confusing JDAM with Laser JDAM.

Boeing makes a clear distinction between the two. Here is Boeing's Laser JDAM page:

http://www.boeing.com/defense-space/missiles/jdam/docs/laser_jdam_overview.pdf

JDAM are now makes WITH LASER TRACKER. Literally none of the new JDAM rolled out of assembly line WITHOUT A TRACKER DEVICE

In September 2012, Boeing began full-rate production of Laser JDAM for US Navy and received a contract for more than 2,300 bomb kits

Joint Direct Attack Munition - Wikipedia, the free encyclopedia

As you can see, a Laser JDAM is simply a normal JDAM with a laser seeker installed at the tip. It's hardly groundbreaking since the Paveway series of laser-guided bombs have been around since the 1960s. The GPS/INS JDAM wasn't delivered until 1997. The first combat use of the JDAM was during Operation Allied Force in 1999. The whole point of JDAM was to improve upon traditional laser-guided bombs, which can be hindered by bad weather conditions like dust, sand, smoke, fog, or cloud cover. GPS/INS guidance also eliminates the need for an aircraft to loiter over a given area to designate the target with a laser, which can be dangerous.

As I said, GPS assisted JDAM are for hard target, WE DON'T USE THEM ANYMORE, almost all were upgraded with a tracker. I don't know about China, but we use our JDAM to hit moving target. It was never GPS guided anyway.

And the JDAMs used during Operation Allied Force didn't have a laser seeker. The basic JDAM is simply an unguided free-fall bomb with a GPS/INS tailkit and body strakes.

gbu32-components.gif


JDAM

f2clDYU.jpg


Laser JDAM (note the laser seeker)

4O8scz6.jpg


I'm sure you called in plenty of JDAMs while playing Call of Duty.:lol:

I said GPS/INS guidance.

You're describing Laser JDAM. See above.

JDAM is what we refer to the Precision Guided Bomb, same as we call all smart phones "Smart Phones" it's a name given for the family. Yeah, Iphone is different than Samsung Galaxy. But is it wrong to call either of them smartphones?? Even with Laser Tracker, the bomb is still being called JDAM. Nobody called them LJDAM, even if you type Laser JDAM in Wikipedia, can you see where are you redirect to?? If you are perfectionist and you cannot accept that LJDAM was being called JDAM, then you should not called JDAM "Smart bombs" too as JDAM is just the upgrade package, the "Bomb" is either a Mk82 Snake eyes or Mk80 General Purpose Bomb. Calling JDAM bombs is not acceptable too then.

Man, you are really gullible.

All in all, my point is not discuss JDAM and how we name JDAM with you, My point is we don't USE GPS Satellite to guide JDAM, open a thread about JDAM and I will be with you argue to the end of the moon.

Again, so, by saying US GPS Satellite guided Smart Munitions, then China would only be having smart munitions as of 2012 when the Beidou system was ready? And even so it's only works in Asia Pacific, it won't guide if China were to fight in EU or North and South America, you need to wait until 2020 when the whole system to cover globally to have smart munitions used globally?

Is this is what you are saying??

Or you are trying to say Chinese smart bomb uses US NAVSTAR satellite for terminal guidance?? :lol:
 
This guys response seems to amaze me a lot.
As often as I make fun of these guys, in a way, I kinda feel sorry for them. Their nationalism I can respect and even admire. But in a military oriented discussion forum, their egos made them snack fishes in a a large pool of a few sharks when they believe they would never meet someone who actually served in a military, let alone in the world's best.

Nevertheless, am trying to teach them how to think logically and critically. One of an analyst's valuable skills is to think backward. If an item in a chain of causes and effects made it here and failed, it must have been successful back there. So let us go back in the process and investigate why.

So if laser designate came before GPS-assist, and I worked with some Pave packages and derivatives, why the need for GPS-assist? Are there things in the combat area or new conditions of warfare that prompted the warfighters and planners to engage the engineers?

I hope the answer is not too hilarious. They have disappointed me in the past but I hate to see another confirmation of what already made me laugh.

The Laser JDAM (LJDAM), as this upgrade is known, adds a laser seeker to the nose of a JDAM equipped bomb, giving the ability to engage moving targets to the JDAM.
So let me get this straight...

According to the Chinese members here, we cannot produce a guidance package to hit a moving large ship at sea, a la the claimed DF-21D, EVEN THOUGH WE CAN HIT A MOVING SMALLER TRUCK OR TANK ON LAND. American LGBs are combat tested against fixed and mobile targets while the claimed DF-21D have yet to produce open water testing. But it is technically impossible for US to enhance the LGB's guidance and install it in a larger weapon.

And these guys are supposed to be my racial and intellectual superiors as how often they told me. :lol:
 
I was making a point that there are more than military GPS Satellite exist.

No, you were trying to mislead and misdirect the reader by going on a tangent and bringing up communications satellites when I was originally talking about an ASAT attack on 31 GPS satellites. One thing has nothing to do with the other.

I NEVER did say MILSTAR guided the bomb themselves.

I'm glad you agree MILSTAR does not guide the bombs.

Now that we have this issue out of the way, I'm going back to my original point.

If the 31 GPS satellites are taken out, the US loses GPS guidance for all of these weapons:

Tomahawk (missile) - Wikipedia, the free encyclopedia

AGM-86C Conventional Air Launched Cruise Missile [CALCM] - United States Nuclear Forces

AGM-158 JASSM - Wikipedia, the free encyclopedia

AGM-84H/K SLAM-ER - Wikipedia, the free encyclopedia

AGM-154 Joint Standoff Weapon - Wikipedia, the free encyclopedia

Small Diameter Bomb - Wikipedia, the free encyclopedia

Joint Direct Attack Munition - Wikipedia, the free encyclopedia

This is by no means a complete list.

All in all, my point is not discuss JDAM and how we name JDAM with you

Fair enough.

My point is we don't USE GPS Satellite to guide JDAM

Yes you do. JDAM is a GPS/INS guided bomb by design. Adding a laser seeker to it doesn't change that fact.

Let's put it like this.

If you lose GPS, JDAM loses several things.

1. You lose the JDAM's all-weather capability.

2. You lose the JDAM's GPS-guided fire-and-forget capability because you now need a targeting pod to designate the target with a laser.

3. JDAM-ER will lose its 40 mile+ stand-off capability.
 
No, you were trying to mislead and misdirect the reader by going on a tangent and bringing up communications satellites when I was originally talking about an ASAT attack on 31 GPS satellites. One thing has nothing to do with the other.

lol....

First of all, Do you actually know how JDAM guide to their target.

First of all, GPS only "Aided" the JDAM guidance system, GPS DOES NOT GUIDE JDAM itself. In fact, even in the Earliest JDAM (the 1990s one) JDAM was designed to work WITHOUT the GPS signal, be it either lost or jammed, GPS DOES NOT GUIDE JDAM, INS DOES.

With GPS the CEP for JDAM are within 5 meter, without, the CEP range from 20 meters to 30 meters depend on free fall range

the JDAM system will provide a minimum weapon accuracy CEP of five meters or less when a GPS signal is available. If the GPS signal is jammed or lost, the JDAM can still achieve a 30 meter CEP or less for free flight times up to 100 seconds

Joint Direct Attack Munition - Wikipedia, the free encyclopedia

How JDAM work? JDAM work by INS Guidance, like you would have with any aircraft today. Instead of a powered flight, the controller is a unpowered glide. GPS in itself DO NOT guide the bomb to its target, instead GPS signal were used to calculate the flight path and put it into the solution, provide the current position of the aircraft in related to the bomb, then INS will calculate a solution of flight path. As stated before, if GPS signal is loss (IE YOU DESTORYED OUR 31 NAVSTAR SIGNAL) then you expect the bomb to drop in a range of 30 meters AT MOST within the target, with GPS, you expect the bomb drop WITHIN 5 meters.

this summed this up very nicely

The navigation system is initialized by transfer alignment from the aircraft that provides position and velocity vectors from the aircraft systems. Once released from the aircraft, the JDAM autonomously navigates to the designated target coordinates. Target coordinates can be loaded into the aircraft before takeoff, manually altered by the aircrew in flight prior to weapon release, or entered by a datalink from onboard targeting equipment, such as the LITENING II or "Sniper" targeting pods.

Joint Direct Attack Munition - Wikipedia, the free encyclopedia

GPS- Provide coordinate
INS - Provide the flight solution

Without the GPS signal, your bomb will not get updated information after leaving the aircraft. It will still be able to obtain a flight solution with INS. Without INS, your bomb become Inert Bomb.

It's the same as with any GPS system you use, with GPS, you will only get a constant stream of "YOUR POSITION" however, if you want to calculate the direction to your destination, you need some kind of Navigation program. It maybe installed in your GPS unit, it maybe not. One very good example is when you use google map (or any kind of mapping apps) on your Iphone or Samsung, you can get your location in a map, but it not will show you the routes of where you want to go. However, if you use Navfree or program like this, you can calculate your route with your GPS, starting from where you are, However, if a GPS signal is not available, you can still get a solution for direction from A to B.

You simply confused the guidance system and the GPS function with INS

Inertial navigation system - Wikipedia, the free encyclopedia


umm, no, without GPS, they will only slightly off target and not so accurate. INS guide those weapon, not GPS.

Fair enough.

Yes you do. JDAM is a GPS/INS guided bomb by design. Adding a laser seeker to it doesn't change that fact.

Let's put it like this.

If you lose GPS, JDAM loses several things.

1. You lose the JDAM's all-weather capability.

2. You lose the JDAM's GPS-guided fire-and-forget capability because you now need a targeting pod to designate the target with a laser.

3. JDAM-ER will lose its 40 mile+ stand-off capability.

1.) No, bomb will still drop, without sophicated accuracy

2.) No, actually, without GPS, your bomb actually become "FIRE AND FORGET" with GPS, the JDAM will become fire and NOT forget.

Again

If the GPS signal is jammed or lost, the JDAM can still achieve a 30 meter CEP or less for free flight times up to 100 seconds

Joint Direct Attack Munition - Wikipedia, the free encyclopedia

3.) No, the stand off range will still be in place, it just not as accurate with GPS signal
 
With GPS the CEP for JDAM are within 5 meter, without, the CEP range from 20 meters to 30 meters

As stated before, if GPS signal is loss (IE YOU DESTORYED OUR 31 NAVSTAR SIGNAL) then you expect the bomb to drop in a range of 30 meters AT MOST within the target, with GPS, you expect the bomb drop WITHIN 5 meters.

It's not that simple.

The scenario described in the Wikipedia article involves a temporary loss of GPS. In other words, the launch aircraft knows its own position, is able to update the JDAM with the proper GPS coordinates prior to weapon release, and the GPS signal is only lost for 100 seconds as the bomb drops to the target. Because of INS drift, the CEP expands from 5 meters to 30 meters during those final 100 seconds.

But in my scenario, it's not just 100 seconds. I'm talking about a permanant loss of GPS worldwide.

Several things change from the Wikipedia scenario:

1. The launch aircraft does not know its own GPS coordinates because there is no GPS.

2. The launch aircraft is unable to update the JDAM prior to weapon release because there is no GPS.

3. The JDAM itself is unable to receive a GPS signal after release from the launch aircraft because there is no GPS.

Do you see how the situation changes now? GPS was not merely lost for the final 100 seconds. GPS was lost for the entire sortie and thus GPS was not available to correct or calibrate the INS at any time during the sortie.

Let's use another example using a different weapon other than JDAM. Let's use the AGM-158 JASSM cruise missle.

AGM-158 JASSM - Wikipedia, the free encyclopedia

The JASSM-ER has a range of 500+ miles and it utilizes GPS/INS for midcourse navigation during those 500+ miles. How do you expect it to stay on course with no GPS to correct or calibrate the INS for 500+ miles? What kind of CEP should we be expecting from a situation like this?
 
As often as I make fun of these guys, in a way, I kinda feel sorry for them. Their nationalism I can respect and even admire. But in a military oriented discussion forum, their egos made them snack fishes in a a large pool of a few sharks when they believe they would never meet someone who actually served in a military, let alone in the world's best.

Nevertheless, am trying to teach them how to think logically and critically. One of an analyst's valuable skills is to think backward. If an item in a chain of causes and effects made it here and failed, it must have been successful back there. So let us go back in the process and investigate why.

So if laser designate came before GPS-assist, and I worked with some Pave packages and derivatives, why the need for GPS-assist? Are there things in the combat area or new conditions of warfare that prompted the warfighters and planners to engage the engineers?

I hope the answer is not too hilarious. They have disappointed me in the past but I hate to see another confirmation of what already made me laugh.



So let me get this straight...

According to the Chinese members here, we cannot produce a guidance package to hit a moving large ship at sea, a la the claimed DF-21D, EVEN THOUGH WE CAN HIT A MOVING SMALLER TRUCK OR TANK ON LAND. American LGBs are combat tested against fixed and mobile targets while the claimed DF-21D have yet to produce open water testing. But it is technically impossible for US to enhance the LGB's guidance and install it in a larger weapon.

And these guys are supposed to be my racial and intellectual superiors as how often they told me. :lol:

lol just answered his post again, he obviously don't really know how INS works.....:lol: Check out his response.

It's not that simple.

The scenario described in the Wikipedia article involves a temporary loss of GPS. In other words, the launch aircraft knows its own position, is able to update the JDAM with the proper GPS coordinates prior to weapon release, and the GPS signal is only lost for 100 seconds as the bomb drops to the target. Because of INS drift, the CEP expands from 5 meters to 30 meters during those final 100 seconds.

But in my scenario, it's not just 100 seconds. I'm talking about a permanant loss of GPS worldwide.

Several things change from the Wikipedia scenario:

1. The launch aircraft does not know its own GPS coordinates because there is no GPS.

2. The launch aircraft is unable to update the JDAM prior to weapon release because there is no GPS.

3. The JDAM itself is unable to receive a GPS signal after release from the launch aircraft because there is no GPS.

Do you see how the situation changes now? GPS was not merely lost for the final 100 seconds. GPS was lost for the entire sortie and thus GPS was not available to correct or calibrate the INS at any time during the sortie.

Let's use another example using a different weapon other than JDAM. Let's use the AGM-158 JASSM cruise missle.

AGM-158 JASSM - Wikipedia, the free encyclopedia

The JASSM-ER has a range of 500+ miles and it utilizes GPS/INS for midcourse navigation during those 500+ miles. How do you expect it to stay on course with no GPS to correct or calibrate the INS for 500+ miles? What kind of CEP should we be expecting from a situation like this?

Several things you got wrong......

1.) Obviously you have not read about how INS work. INS was created "Pre-Space Flight" the function of INS DOES NOT REQUIRE a functioning GPS to work.

An inertial navigation system (INS) is a navigation aid that uses a computer, motion sensors (accelerometers) and rotation sensors (gyroscopes) to continuously calculate via dead reckoning the position, orientation, and velocity (direction and speed of movement) of a moving object without the need for external references. It is used on vehicles such as ships, aircraft, submarines, guided missiles, and spacecraft. Other terms used to refer to inertial navigation systems or closely related devices include inertial guidance system, inertial reference platform, inertial instrument, inertial measurement unit (IMU) and many other variations.

Inertial navigation system - Wikipedia, the free encyclopedia

INS work like this.

For the planes. You input your airbase Co-ordinate in your INS computer (An info you can have without the use of GPS), INS computer will calculate the change of position by making dead reckoning nav, say you start at geo-coordinate (0,0) you move left at 5 minute at 1 unit per minute. INS will work out now you are a (0,-5) If you move straight for another 5 minutes with a speed of 1 unit per minute, then INS will update your co-ordinate to (5,-5), so INS can calculate any position by how the aircraft move from the IP, and the IP can be obtained without the help of INS.

Infact the first human flight via INS was made in 1952 , way BEFORE space ages. INS does not require a function GPS system. This is what it said.

Let's recap your "Scenario"

1. The launch aircraft does not know its own GPS coordinates because there is no GPS.

2. The launch aircraft is unable to update the JDAM prior to weapon release because there is no GPS.

3. The JDAM itself is unable to receive a GPS signal after release from the launch aircraft because there is no GPS.

1.) It will not happen like you said as the flight know the co-ordinate of their base, thru continuous calculation using INS dead reckoning by making calculation the speed, direct and orientation. The flight will kept it's position updated even without a function GPS. As INS will keep update the position of the craft,(albeit not as accurate as GPS) and the co-ordinate will still be Hot.

2.) Wrong again, Flight can obtain their own position via INS Dead reckoning calculation, and using said co-ordinate will update the Co-ordinate of the JDAM.

3.) Wrong again, GPS signal will not guide the bomb to target, it's the INS calculate the flight path not GPS. GPS update the position of the bomb, but did not involve in the Actual calculation of the flight path. Indeed without a functioning GPS, the bomb will fall not as accurate as the dead reckoning IP (Initial Point) by the aircraft will not be as accurate depend on INS equipment maintenance.

SO you just need to input the current co-ordinate calculated by the planes own INS and transfer those data into JDAM INS system, and viola, you have your current position.

It's not that hard to understand.

It will be wrong again for the JASSM-ER.

You can input the IP co-ordinate without the help of a GPS, and INS will calculate the current position via inflight movement. Same deal. You just don't know how INS work, that's all.

Of course, using GPS will help INS a lot, but it is not a must, you literally saying INS must depend on the GPS system, which is wrong, INS pre-date the GPS system, this is the second thing you got wrong.
 
I don't think you understand how INS drift works.

Inertial navigation system - Wikipedia, the free encyclopedia

All inertial navigation systems suffer from integration drift: small errors in the measurement of acceleration and angular velocity are integrated into progressively larger errors in velocity, which are compounded into still greater errors in position. Since the new position is calculated from the previous calculated position and the measured acceleration and angular velocity, these errors accumulate roughly proportionally to the time since the initial position was input. Therefore the position must be periodically corrected by input from some other type of navigation system.
 
It's also important to note that errors associated with INS drift are cumulative and get progressively worse the longer you go without a GPS update—because errors build on errors.

EsnWDMR.jpg


Note that it gets worse with the passage of time:

XU32cm6.jpg


I have a question for you.

How long does it take for a subsonic JASSM to cover 500+ miles?
 
I don't think you understand how INS drift works.

Inertial navigation system - Wikipedia, the free encyclopedia
I do. And I have real experience working with a variety of independent and slaved INS configurations while you do not.

The astro tracker navigation in the FB-111 and other vessels corrected INS drift long before GPS gained primacy as INS correlated method. The method was in use in the SR-71 and U-2/TR-1 series as well.

Other methods such as radar terrain matching that uses known ground features to correlate and correct INS drift. Other airborne vessels can also use each other to correlate and correct INS drift. We worked on these and other methods when PLAAF pilots were still learning formation flying. :lol:
 
It's also important to note that errors associated with INS drift are cumulative and get progressively worse the longer you go without a GPS update—because errors build on errors.

Note that it gets worse with the passage of time:

I have a question for you.

How long does it take for a subsonic JASSM to cover 500+ miles?
Modern ring laser gyros are .1nm/hr or even less in INS drift. For a high subsonic cruise missile to cover that distance, which is about 430-450 nm, by the time it get to its target area, we are looking at line-of-sight distance error. For a high subsonic B-1 with its bomb load, the target -- any where in China -- is dead.
 
The astro tracker navigation in the FB-111

Does JASSM have an astro tracker?:lol:

Other methods such as radar terrain matching

Does JASSM have TERCOM?:lol:

Modern ring laser gyros are .1nm/hr or even less in INS drift.

I want you to substantiate your claim of .1nm/hr. Post some links.

Also post some links to show that modern PGMs have been upgraded with this new INS system.
 
Does JASSM have an astro tracker?:lol:



Does JASSM have TERCOM?:lol:
You Chinese here do not have much critical thinking, along with the experience related to the subjects under discussions. The question is not whether a specific platform have such and such feature. It is about your so far ridiculous belief that the US military cannot perform without GPS. Even more ridiculous the idea that China can take out all of our GPS satellites.

I want you to substantiate your claim of .1nm/hr. Post some links.

Also post some links to show that modern PGMs have been upgraded with this new INS system.
Too lazy to do keyword search?

But here is a clue for your homework...

rlg_gilles_zpsd403297d.jpg


See the highlighted? Better than means a lower figure than .8 nm/hr. So over 500 nm distance, we really do not need GPS at all. A fully loaded B-1 can provide laser guidance to its SDBs to take out a PLAAF airfield on the first pass. All without GPS. But then again, going by the Chinese members' mentality: If China have not done <something>, nobody can do it.
 
Still waiting for gambit to back up his own claim of .1nm/hr. The burden of proof is on the person who made the claim. I don't have to disprove anything.

In the meantime, I'll post more stuff to back up my side.

Here's a decent Wired article about this very subject.

Is the author lying?

When GPS Goes Down, Pentagon Still Wants a Way to Fight | Danger Room | Wired.com

Right now, the agency notes, the military’s navigation systems primarily rely on a pairing of two devices: GPS, which uses satellite data, and what’s known as an Inertial Navigation System (INS), which relies on “dead reckoning” (using estimates of speed and direction, without external references) to provide locational intel.

It’s a tactic that’s accompanied by several problems. For one, INS — because it uses internal, ongoing estimates — is notoriously error-prone without a GPS system to back it up, so it can’t be relied upon exclusively. And INS systems often obtain their starting position and velocity from a GPS device. Which means if the GPS is under attack, the INS risks leading military personnel (or the drone or weapon they’re navigating) astray.
 

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