CV-17 Shandong (002 carrier) Thread I ...News, Views and operations

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plawolf

Lieutenant General
Exactly They can weed out civilian ship by filtering it out using AIS Automatic ship identification system
Every civilian ship carry transponder with them to avoid collision That is insurance,international maritime body requirement Military ship does not carry transponder for the obvious reason
The typical carrier outline is very distinct Plus it emit all kind of radio and electromagnetic signal
Then you have CAP necessitating plane take off and landing all the time So it has distinct signature

By now China has 30 or 40 Yaogan, Shijian and other specialized satellite orbiting the earth Plus more than 130 dual use satellite that can be marshaled to help find the carrier

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A marine traffic coordinator using AIS and
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to manage vessel traffic.
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An AIS-equipped system on board a ship presents the bearing and distance of nearby vessels in a radar-like display format.
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A graphical display of AIS data on board a ship.
The automatic identification system (AIS) is an automatic tracking system that uses
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on ships and is used by
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(VTS). When satellites are used to detect AIS signatures, the term Satellite-AIS (S-AIS) is used. AIS information supplements
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, which continues to be the primary method of collision avoidance for water transport.[
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]

Information provided by AIS equipment, such as unique identification,
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,
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, and speed, can be displayed on a screen or an
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. AIS is intended to assist a vessel's
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officers and allow
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authorities to track and monitor vessel movements. AIS integrates a
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transceiver with a positioning system such as a
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receiver, with other electronic
navigation sensors, such as a
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or
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. Vessels fitted with AIS transceivers can be tracked by AIS base stations located along coast lines or, when out of range of terrestrial networks, through a growing number of satellites that are fitted with special AIS receivers which are capable of deconflicting a large number of signatures.

The
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's
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requires AIS to be fitted aboard international voyaging ships with 300 or more
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, and all passenger ships regardless of size.
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For a variety of reasons, ships can turn off their AIS transponders.
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And what if enemy warships broadcast civilian AIS signals? Better to clear the board of civilian ships altogether.
 

gelgoog

Brigadier
Registered Member
US supercarriers are large enough to be easily spotted using an imaging satellite. As satellite launch costs keep shrinking the cost to put up a constellation will keep getting smaller and smaller. As for not having 24/7 coverage it's not like you need it. Carriers are slow enough and the distances are large enough that you do not need to have that fine time resolution.

Also it wouldn't be the first time a reconnaissance satellite had a limited ability to move its orbital position. Given modern ion engine technology you could have a coarser grid of satellites to provide a rough estimate of the position and a smaller amount of higher resolution satellites which can move their orbital position to increase coverage over a specific area of conflict or of interest.
 

Hendrik_2000

Lieutenant General
And what if enemy warships broadcast civilian AIS signals? Better to clear the board of civilian ships altogether.

Well they can fake it but it is hard to do because the original ship location can tracked So the original and fake can't be on separate location by much Anyway Indian think tank did some study 2 years ago and their conclusion China has enough satellite in the orbit to give it persistence track on carrier
So did Henri K

Anyone still in doubt as to the Chinese capability to track ship at sea should read this excellent treatise on the subject It is a long one I provide the link but unfortunately in French If anyone interested I can translate it but I provide the conclusion. Basically it said no more place to hide unlike in WWII
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IV. Analysis of the capabilities of the global system

There are two ways to approach marine surveillance:
  1. detect and identify all ships in a more or less wide area
  2. once identified, track over time only the vessels of interest
To assess the capabilities of the Chinese reconnaissance system, let's take conservative assumptions about satellite capabilities:

  • In times of crisis the warships strongly limit their emissions, which makes the ELINT system blind.
  • SAR constellations have only 2 active satellites each
  • SAR satellites have a swath of 300km, and insufficient resolution to identify ships.
  • Optical satellites in low orbit do not have a swath sufficient to be useful, except for the JB-9 wide-field constellation.
  • For the JB-9 constellation, satellites have a swath of 300km and can not image at night. It has 4 active satellites.
  • The satellites can image 10 minutes per orbit, giving a maximum swath length of 4000km.
  • The geostationary Gaofen-4 satellite can not detect smaller vessels than an aircraft carrier.


For a given place, during the same day, there are 12 satellite passes:

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Local time of satellite passes during the day

Detection and identification
With regard to the detection of all vessels over a wide area, as a first approximation (without taking into account the movement of the ships) the interesting quantity is the total field of view of the satellites, compared to the distance between two passes . Indeed, if a satellite has a 3000km field of view, and when it passes vertically from one point during an orbit, it passes 3000km further in the next orbit (which is typical for a satellite in orbit bass), then he is able to scan the entire earth's surface.

With the previous assumptions the combined swath would be 300km x 12 = 3600 km. The system could therefore provide a complete sweep over an area of 4000km in the North-South direction, and at least 3200km in the East-West direction, within a single day. However, as only JB-9s can identify a vessel, vessel identification would only be possible on one-third of the area, which would allow some vessels to pass through the net for a period of time.

Follow-up over time
In order to track a ship that has been identified in advance, in order to be able to locate it at regular intervals, it is best that the passes be distributed at regular intervals throughout the day. This is not the case, so it may take up to 4:40 between two successive passes (YG10 and YG18 in the evening). This is enough for a ship to travel 250km at 30 knots, and therefore if it has changed course, probably comes out of the field of view of the satellite in charge of following it.

In addition, SAR satellites flying relatively low, they have only one chance out of two to pass sufficiently above a given ship to be able to image. A fast maneuvering ship often has a good chance of regularly escaping the constellation's surveillance, forcing it to re-enter a research phase.

However, around 10:00 am and 1:30 pm local time, the JB-9 satellite pair passes provide the position, course and speed of a ship (if the first satellite has managed to find the ship, the second can find it and thus calculate its average speed), and confirm its identification. This provides a solid track that could serve as a firing solution for fast missiles like the
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, or more conventional missiles launched from a ship or aircraft already placed close to the target.

Conclusion

China has a triple capability radar, optical and electronic detection, identification and tracking of ships at sea. Even without taking into account the real-time tracking capability from the geostationary orbit, the large optical constellation JB9 field and SAR constellations JB-5 and JB-7 can scan a wide area every day to find contacts of interest, and have a good chance to refresh the tracks of the most interesting contacts every few hours, even for ships without electromagnetic emissions. As a result, it seems unlikely that an opposing naval group will be hiding in the ocean for a long time.

However, in case of very large cloud cover, only SAR satellites can be used, which can severely limit the identification and monitoring capabilities of the system. That does not mean that China would be blind: other means of detection, like
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, or simply its
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can complement the satellite system, and thus seriously question the invulnerability of US aircraft carriers to the sea. The intervention of the United States to intervene in a new crisis in Taiwan would be much more risky, and therefore much less likely.
 

antiterror13

Brigadier
US supercarriers are large enough to be easily spotted using an imaging satellite. As satellite launch costs keep shrinking the cost to put up a constellation will keep getting smaller and smaller. As for not having 24/7 coverage it's not like you need it. Carriers are slow enough and the distances are large enough that you do not need to have that fine time resolution.

Also it wouldn't be the first time a reconnaissance satellite had a limited ability to move its orbital position. Given modern ion engine technology you could have a coarser grid of satellites to provide a rough estimate of the position and a smaller amount of higher resolution satellites which can move their orbital position to increase coverage over a specific area of conflict or of interest.

how about to put a very small device on the carrier .. like insect/fish drone that can give a clue where the carrier is
 

gelgoog

Brigadier
Registered Member
AFAIK beyond optical telescopes which operate in visible light and SAR satellites there are also telescopes which operate in the IR spectrum. Those could probably detect a carrier even though clouds. It stills emits high temperature steam clouds from the boilers. Plus any US supercarrier will be accompanied by a task group. Which will make it highly visible.

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asif iqbal

Lieutenant General
again not possible

you cannot track a carrier strike group using satellite

even if you employed all your assets like UAV, Reconnaissance, Tracking, Jamming, Under water Great Wall, Satellites and Emissions technology in a limited sea area you still will be hard pushed to locate, track and follow a carrier on a continuous basis

if it could be done no one would build carriers
 

subotai1

Junior Member
Registered Member
again not possible

you cannot track a carrier strike group using satellite

even if you employed all your assets like UAV, Reconnaissance, Tracking, Jamming, Under water Great Wall, Satellites and Emissions technology in a limited sea area you still will be hard pushed to locate, track and follow a carrier on a continuous basis

if it could be done no one would build carriers

You are welcome to your opinion, with or without facts to support it. However, it can and is being done and with vessels far smaller than carriers. In addition, why would tracking carriers make someone not want to build them? Their goal is force projection, not stealth.

And, btw, when you see that shipping companies and builders are now moving towards autonomous ships, you know that the tracking issue is solved (e.g.
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).

Now, here are some more articles on the subject if you are so inclined:

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asif iqbal

Lieutenant General
this discussion reminds me of a similar discussion after WWII

US had the biggest navy in the world but with nuclear weapons what would be the purpose of 1,000 ship navy if nukes could take them out?

after tests at Bikini Atoll it was clear nukes couldn't take out a navy, only ships that were destroyed were ones that were parallel to the blast and within few kms of centre of the blast

world was ready to move on and keep building large ships and navy

same goes for carriers, in 1980s same question raised and answered

if carriers could be tracked no one would be building them, in-fact now everyone wants a carriers
 

subotai1

Junior Member
Registered Member
if carriers could be tracked no one would be building them, in-fact now everyone wants a carriers

You can keep saying that all you want, but frankly, carriers have been trackable for the last 30 years. I suggest you read up on the new technologies called "submarines" and "SOSUS".
I also suggest a new thread for this topic. Maybe we can call it "talking to flat earthers."
 
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