Modern Carrier Battle Group..Strategies and Tactics

Re: The End of the Carrier Age?

NikeX said:

"SAR is essentially an AESA radar. It is called SAR because of the mapping capability"

Comment: I think you are confused about how Synthetic Aperture Radar (SAR) works. The SAR works similar to a phased array, but contrary of having a large number of parallel antenna elements like a phased array, SAR uses one antenna in time-multiplex. The different geometric positions of the antenna elements are result of the moving platform.

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Well, I have to dumb it down incase certain member finds this information too much to handle.

NikeX said:

In other words the motion of the antenna along a track causes it to resemble a very large antenna and enjoy the increased resolution that results. The synthetic aperture is produced by signal processing that has the effect of lengthening the antenna. Using such a technique, radar designers are able to achieve resolutions which would require real aperture antennas so large as to be impractical with arrays ranging in size up to 10 m.

In other words it is like taking a series of snapshots of something as you move along a track and then integrating those individual snap shots to produce one detailed picture of the object in question

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Yes, that's how it would be done essentially. However, what certain member fails to grasp is that ship detection and identification makes use of phase and polarization information coming from the raw data. But by insisting on a pure image processing example, he analogy no longer describes a radar but a fancy optical sensor, so it is unrealistic.

Re: »Ø¸´: The End of the Carrier Age?

Igor said:

The US can't hide any of it's carriers. China could dedicate a real time imaging micro-satellite constellation to every carrier in every ocean on earth and use that to track them 24/7 and guide missiles towards them in conjuction with drone sweeps/radar/etc.

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you can't track ships 24/7 for what 2 yr, 10 yrs.

Re: »Ø¸´: The End of the Carrier Age?

"....China could dedicate a real time imaging micro-satellite constellation to every carrier in every ocean on earth and use that to track them 24/7 and guide missiles towards them in conjuction with drone sweeps/radar/etc...."

The way I would handle that would be to jam the datalinks of the micro-satellites so that what they observed would not get back to a central headquarters. If they are micro-satellites then the power would be in the swarm as each individual satellite would be weak and easily overwhelmed. Or I would give some micro-satellite swarm a series of false targets to cause them to think they have detected the carrier but in reality had only detected a frigate broadcasting a carrier signature. There are many ways to defeat detection and the US Navy has seen them all. Don't forget they train all the time for these types of contingencies

Re: The End of the Carrier Age?

s002wjh said:

and as i said many time before if the radar cover a large area, the resolution goes down, a carrier might only occupy 1 pixel. unless you know the RF frequency signature from US carrier, you are not gonna able to ID it.

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So detection isn't a problem then. I'm glad we are making progress.

s002wjh said:

the surface of ship and its wake can be detect by radar, but in a million sq mile there is gonna be alot ships, many are large steel ships.

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its much easier to detect and ID the ship if the coverage of image is smaller, and the carrier occupy large amount of pixiels so image processing and other algorithm can recognize it. much more difficult if the radar image cover large area.

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There is no limitation that detection, tracking, and identification has to be done with one scan and with one scan setting. I have already pointed out in here and here that beam width can be adjusted for identification purpose and that strategies can be employed for more efficency. I like how you simply ignore what I have said, and ask me the exact same question again.

Repeating an example which has already been addressed is not going to strengthen your arguements.

s002wjh said:

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ships detect by SAR after post-processing. without further zoom in, processing, you can't id which is which. the more ship it detect the more resource need it to ID those.

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The caption of that image says: "This SAR image shows an area of the sea near a busy port. Many ships can be seen as bright spots in this image due to corner reflection. The sea is calm, and hence the ships can be easily detected against the dark background." Even without the caption, we can see that this is not a situation which occurs in open ocean. You are being rather disingenous here.

Re: The End of the Carrier Age?

s002wjh said:

A active radar only contain its own frequency, the receiver use it to determine its own transmit signal or not.

read this

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Of course radar only detects its own frequency, but this has absolutely no relevance to what I have said regarding employment of search algorithm and tightening the beam for identification. It has nothing to do with ELINT satellites as these satellites don't carry active radar. It also does not support your argument that CVBG cannot be detected, tracked, and identified by SAR satellites.

Re: »Ø¸´: The End of the Carrier Age?

NikeX said:

"....China could dedicate a real time imaging micro-satellite constellation to every carrier in every ocean on earth and use that to track them 24/7 and guide missiles towards them in conjuction with drone sweeps/radar/etc...."

The way I would handle that would be to jam the datalinks of the micro-satellites so that what they observed would not get back to a central headquarters. If they are micro-satellites then the power would be in the swarm as each individual satellite would be weak and easily overwhelmed. Or I would give some micro-satellite swarm a series of false targets to cause them to think they have detected the carrier but in reality had only detected a frigate broadcasting a carrier signature. There are many ways to defeat detection and the US Navy has seen them all. Don't forget they train all the time for these types of contingencies

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There is a reason why serious business is done with full scale satellites rather than miniture ones, and that is the latter ones don't have space for jack. The larger the satellite, the more solar panels it can carry, the more fuel it can carry, and the bigger sensor it can carry. Bigger sensor means resolution and sensitivity are better.

Re: The End of the Carrier Age?

Just to add a little more to the SAR debate there is the problem of slant range. A distortion can occur. In other words The slant-range distortion occurs because the radar is measuring the distance to target in slant-range rather than the true horizontal distance along the ground. This results in a varying image scale, moving from near to far range. A ship detected near the edge of the SAR of a passing radar satellite might suffer this distortion and misinterpret what it had seen. You can be sure that this weakness would be exploited by the carrier to avoid detection.

Re: »Ø¸´: The End of the Carrier Age?

This is a good discussion and I am enjoying all the input. However I must go now as I have a series of tasks that require my attention. Thanks

Re: The End of the Carrier Age?

Engineer said:

So detection isn't a problem then. I'm glad we are making progress.

sure you can detect all ships in 1000 sq mile, then doing it over and over to cover a million mile area. take alot time and resource. then you have to know which ship is the carrier. prioritize require more information than detection.

There is no limitation that detection, tracking, and identification has to be done with one scan and with one scan setting. I have already pointed out in here and here that beam width can be adjusted for identification purpose and that strategies can be employed for more efficency. I like how you simply ignore what I have said, and ask me the exact same question again.

i said it before it doesn't matter how many satelite or process step you use. to cover that much area, id 1 target out of many, in a short time. i doubt any nation has that capabilities right now.
as my analogy put 2000 different size needle bury in a 50sq mile beach, grab 100 people with metal detector or other detector find 1 needle out of those 2000. sure you can find it EVENTUALLY. now if that needle keep moving, its gonna be tougher to find it.


Repeating an example which has already been addressed is not going to strengthen your arguements.


The caption of that image says: "This SAR image shows an area of the sea near a busy port. Many ships can be seen as bright spots in this image due to corner reflection. The sea is calm, and hence the ships can be easily detected against the dark background." Even without the caption, we can see that this is not a situation which occurs in open ocean. You are being rather disingenous here.

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wait the last part I give you an ideal situation. but are you saying detection is much more difficult? seem like you contradict your self.

does this image better less ship, less calm sea


china, SK, japan, south china sea has one the largest volume of ships traveling through that area. how many ships do you think from coast of china to australia to japan.

larger area of coverage. due to larger area, false alarm is gonna be higher, since resolution of ship is lower, ships might only occupy 1 pixels

Re: The End of the Carrier Age?

Engineer said:

Of course radar only detects its own frequency, but this has absolutely no relevance to what I have said regarding employment of search algorithm and tightening the beam for identification. It has nothing to do with ELINT satellites as these satellites don't carry active radar. It also does not support your argument that CVBG cannot be detected, tracked, and identified by SAR satellites.

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i never say CANNOT, i said if china know the general location of CVBG. itll be easier, but if they have to blindly search ocean from china to australia to japan then its much more difficult.

sar image processing

the radar antenna point along
fixed position direction with respect to the flight platform
path, and the antenna footprint covers a strip on the
illuminated surface as platform moves .

The radar transmits pulses at the pulse repetition
frequency, PRF, and for each pulse the backscatter return
from the ground is sampled in range at the analog to digital
(A/D) sampling frequency. The radar operation is coherent,
which means that both the return magnitude and phase
(with respect to the transmitted signal) are sampled. For
each range sample the in-phase and quadrature values (I
and Q) are stored. The raw data file is thus a twodimensional array of complex values (with I as the real part
and Q as the imaginary part). This two-dimensional data
set is then processed to form an image.

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