Chinese Missile News

[DevendraRajput]

We agree to disagree You said satellite cannot track a plane I prove it for all the world to see SATELLITE CAN TRACK MOVING PLANE CAPICI! SAR can track movement as Chat GT said and support by paper AGain YOU ARE WRONG

You are still avoiding what will satellites operating in visible light will do in night and in cloudy weather.

 

[DevendraRajput]

NOT only OVH but also satellite tracking heard of SIBIR? How do you think SIBIR works it can track missiles flying in Space and you said you cannot track a plane?

Again, SIBR is for detection and not tracking.

 

[NGAD IS THE BEST]

You are still avoiding what will satellites operating in visible light will do in night and in cloudy weather.

IR and low light cameras are being used for Satellites since ages, especially spy and earth observing Satellites using this technology since mid 70s

 

[Hendarto]

Again, SIBR is for detection and not tracking.

How do you think the US defeated the Iran missile They tracked and calculated the most likely trajectory of the missile, then sent an SM 6 or SM 3 to counter it

 

[Hendarto]

You are still avoiding what will satellites operating in visible light will do in night and in cloudy weather.

I already explain it no need for me to keep repeating it ad noseum!

 

[gambit]

So far I have not seen any adequate explanation on how synthetic aperture radar (SAR) works despite claims of showing sources that supposed to show how the concept works. So here goes...

Imagine you are taking a picture of a model. Say a nude woman to make it interesting. Your camera have a limited aperture as all lenses do. You take one snapshot, move one meter, take another snapshot, move one meter, take another snapshot, and so on, until you completed a full circle of the model. Each snapshot adds to the previous and the sum is logically larger than the actual lens physical aperture. That was a simplified explanation of a 'synthetic' or fake aperture. The critical component here is that you have to move.

The weakness of the SAR concept is: What if the model move? In other words, a SAR works best when the target is mostly stationary. Moving targets produces noise in the SAR signal processing.

Moving objects and their displacement in SAR images - Geoawesomeness

The launch of high resolution radar satellites such as the German TerraSAR-X satellite (launched in summer 2006, resolution of 1m, 3m or 16m m depending on the recording mode) opened new possibilities in monitoring traffic flows from space. Indeed, the German Aerospace Centre (DLR) has developed...

geoawesomeness.com

However, the detection of moving objects faces some difficulties, as the motion on ground provokes a shift of the object in the SAR image. Moving objects appear shifted from their actual road or network position: Cars or trucks seem to drive on fields; trains, which are well represented as whitish long lines (see figure below), are shifted into the surroundings of the actual tracks and also ships appear apart from their actual route (see second image below).​

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...standard SAR-processing methods are based upon the assumption of a static scene or in other words the stationary of the detected objects. If the target has a velocity component, its doppler shift is changed compared with that from a stationary reflector. As a consequence the SAR gets confused and produces artefacts in the final image displacing the motion objects.​

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To detect moving objects...​

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Two SAR antennas are spatially aligned...​

In other words, to TRACK moving objects using SAR, at least two SAR platforms must be in play. Motion detection is not tracking. Motion detection is about responding to a change. Tracking is about CONSTANT responses to continuous changes. Critical difference is that the latter requires much more processing power.

One SAR can track ships, but not an airplane. The system can display image shifts, noise, and assort anomalies that will point to the airplane, but it cannot track the airplane with the granularity of a regular radar.

Can a SAR detect and track an F-22? At this point -- no.

 

[DevendraRajput]

Can a SAR detect and track an F-22? At this point -- no.

Can SAR sat find firing solution on a C-17 flying at 900 KMPH? I highly doubt. And even if in future it becomes a possibility, simple countermeasure will be RAM coating the top of C-17s, SAR emitters are far, very far from the target making wavefronts massive and lowering the power density of the incoming signal. RAM coating will reduce reflected power even more making SAR sats to further lower the accuracy of position and velocity.

Its an interesting problem. To keep the satellite numbers manageable, they have to park them higher, with geostationary orbit giving the best way to cover a swath of land. But if you park your SAR sats in geostationary, you have a massive distance to cover and signal's power density will be lower.

 

[DevendraRajput]

How do you think the US defeated the Iran missile They tracked and calculated the most likely trajectory of the missile, then sent an SM 6 or SM 3 to counter it

You really need to study the architecture of a simple anti air or even a BMD system. SBIS can not find firing solution to launch SM3. Nope.

 

[DevendraRajput]

In other words, to TRACK moving objects using SAR, at least two SAR platforms must be in play. Motion detection is not tracking. Motion detection is about responding to a change. Tracking is about CONSTANT responses to continuous changes. Critical difference is that the latter requires much more processing power.

Since morning I am trying tell him that detection, motion detection and tracking are not the same thing. And for finding a firing solution and to keep on guiding a missile, one needs an accurate location and velocity of target, being updated in real time.

There is a reason why fire control radar are a specific function. But then, people here like to jump to conclusion without fundamentals.

 

[DevendraRajput]

That was a simplified explanation of a 'synthetic' or fake aperture. The critical component here is that you have to move.

The first thing that I told him. The act of moving itself introduces a delay. Its a function of your relative orbital velocity. For stationary things like landmass, its okay. You will get nice high resolution black and white pictures. For fast moving things like an airplane? Nope!


You will get a blurry line.

 

[Hendarto]

The missile itself has a sensor or radar and control guidance. The satellite detects and tracks the target then it passes the info and gives the approximate location of the target! The same principle as the INS targeting

You really need to study the architecture of a simple anti air or even a BMD system. SBIS can not find firing solution to launch SM3. Nope.

I am no expert in Aperture radar so I asked Chat Gt my question about how SAR satellites fix a moving target here is the answer. See note no 4 on how they mitigate the blurring effect. It can be done!

chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://icerm.brown.edu/materials/Slides/sp-f17-offweeks/Discussion_of_Radar_and_Moving_Targets_%5d_Armin_Doerry,_Sandia_National_Laboratories.pdf

Synthetic Aperture Radar (SAR) is a powerful technology that can detect and track moving targets. Let’s explore how SAR achieves this:

1. Doppler Effect in SAR:
   • When a radar signal reflects off a moving target (such as an aircraft or ship), the Doppler effect comes into play.
   • The Doppler effect causes a change in the frequency of the reflected signal due to the relative motion between the radar and the target.
   • Here’s how it works:
     • As the target moves toward the radar, the reflected signal has a higher frequency (blue-shifted).
     • When the target moves away from the radar, the reflected signal has a lower frequency (red-shifted).
   • By analyzing these frequency shifts, SAR can determine the range rate (rate of change of distance) of the moving target1.
2. Moving Target Indicator (MTI) Modes:
   • SAR employs various MTI modes to handle moving targets:
     • Ground-Moving-Target Indicator (GMTI): Detects moving objects on the ground, such as vehicles or ships.
     • Surface-Moving-Target Indicator (SMTI): Focuses on detecting moving targets on the Earth’s surface.
     • Airborne-Moving-Target Indicator (AMTI): Used for detecting moving aircraft.
     • Video-SAR: Provides real-time imaging of moving targets.
   • These modes account for the Doppler shifts caused by target motion, allowing SAR to distinguish between stationary and moving features1.
3. Spatially-Dependent Phase Change:
   • In GMTI, the assumption is that the time delay between radar pulses increases linearly with pulse index.
   • However, when a target is moving, this assumption breaks down.
   • The pulse-to-pulse phase change becomes spatially dependent due to the target’s motion.
   • SAR compensates for this effect to accurately position moving targets in the imagery1.
4. Autofocusing and Phase Correction:
   • To mitigate blurring caused by moving targets, SAR employs techniques like autofocusing.
   • Autofocusing corrects for the spatially varying phase changes introduced by moving objects during aperture synthesis.
   • By adjusting the phase of the radar echoes, SAR sharpens the image and accurately places moving targets2.

In summary, SAR’s ability to handle moving targets relies on understanding the Doppler effect, specialized MTI modes, and sophisticated phase correction algorithms.

 

[Hendarto]

You really need to study the architecture of a simple anti air or even a BMD system. SBIS can not find firing solution to launch SM3. Nope.

You are wrong here what chat Gt said about Sibir

• These satellites can identify the missile’s type, burnout velocity, trajectory, and likely point of impact.
• Notably, SBIRS can track missiles even over theater areas of interest while maintaining global coverag

1. Detecting Missile Launches:
   • SBIRS satellites continuously scan the entire Earth’s surface using infrared (IR) sensors.
   • They detect the IR signatures of missiles during their boost phase after launch.
   • These satellites can identify the missile’s type, burnout velocity, trajectory, and likely point of impact.
   • Notably, SBIRS can track missiles even over theater areas of interest while maintaining global coverage1.

 

[DevendraRajput]

The missile itself has a sensor or radar and control guidance. The satellite detects and tracks the target then it passes the info and gives the approximate location of the target! The same principle as the INS targeting

Alright, few things...

There is nothing called "INS targeting". INS can not target anything because it is a completely passive guidance system to arrive a fixed position based on the starting position. It does use GPS update to correct error that accumulate but in itself it is completly passive requiring no emission of any radio waves. Meaning, it can not target anything because... it does not know where that thing is.

And, satellites can not really track fast moving targets like aeroplanes over a long distance. This is a fantasy that you have cooked up.

Now the sensor part you are talking about is called terminal guidance in parlance of missiles. Also called seeker at times. And it is resposible for final guidance to the target. But before that, the missile still needs to be guided near the target and that part is done by fire control radar. And no, for fast moving targets like aeroplanes, you can not replace them with satellites.

I am no expert in Aperture radar so I asked Chat Gt my question about how SAR satellites fix a moving target here is the answer. See note no 4 on how they mitigate the blurring effect. It can be done!

Be VERY careful of what chapgpt produces. It is very sensitive to your input question. And at times it can be wrong as well.

You should ask ChatGPT, "Can a space based SAR satellite replace a fire control radar in a surface to air missile system?" and read the answer.

 

[Dalit]

@Hendarto Nice one bud.

 

[DevendraRajput]

You are wrong here what chat Gt said about Sibir

• These satellites can identify the missile’s type, burnout velocity, trajectory, and likely point of impact.
• Notably, SBIRS can track missiles even over theater areas of interest while maintaining global coverag

1. Detecting Missile Launches:
   • SBIRS satellites continuously scan the entire Earth’s surface using infrared (IR) sensors.
   • They detect the IR signatures of missiles during their boost phase after launch.
   • These satellites can identify the missile’s type, burnout velocity, trajectory, and likely point of impact.
   • Notably, SBIRS can track missiles even over theater areas of interest while maintaining global coverage1.

Ask this. "Can SBIS replace a fire control radar and guide a Surface to Air missile to its fast moving target"?

You will get your answer.