The Chinese maritime surveillance system

[gosnold]

I have written a blog post on the Chinese maritime surveillance satellites, with a list of these satellites, and an analysis of the coverage they might provide. In section IV of the post, there is an animated gif to visualize the coverage.

I thought some people here might find it interesting.

[Gunner98]

Excellent stuff gosnold. I went from knowing absolutely nothing about Chinese satellites, to -very well informed - in a very easy and enjoyable read.

Thank you

[Dysta]

Excellent contribution.

It's far from globally non-stop surveillance, but the regional and intel gathering methods are getting sharper at 2010s.

I think it's also worth to tell the Beidou formation, for dual-use positioning and unit/weapon guidance without foreign satellites.

[BradOrbital]

Nice coverage there gosnold, thanks.

[tjhkkr]

That was really cool... Thanks!

[kevinkins]

Very impressive. Thank you for the link. It could not have found a more interested audience.

[mikkey]

Excellent gosnold, thanks for sharing.

[Hongjian]

Thank you, gosnold.

Good to know that more PLA watchers are contributing to this forum.

[ExNusquam]

Gosnold, this is easily one of the best open-source pieces on Chinese space based ISR, and the implications of that for building a firing solution. I fully concur with you that there are two targeting windows, where there are closely spaced passes by a SAR bird followed by an EO bird. I only have a couple of minor technical points:

1. You asses that if the SAR birds flew in pairs they could do positive ship ID. I doubt this is possible beyond basic dimensions and RCS due to the effects of target motion on SAR. A moving target will be a blurry, smeary mess at high resolution and a slightly less blurry, smeary mess at lower resolution. The streaking in the example of the oil tanker (left) is caused by the relatively small motion of the ships radars; I suspect the ship itself is stationary.

2. I have suspicions about the ability of the GF-4 to effectively track BLUFOR ships. Here's a screenshot from MarineTraffic showing AIS hits just North of the Marianas (inside the second island chain)...there are a lot of vessels out there that will generate sizable wakes. A 50m EO GSD means a Carrier will be 6 piles on a GF4 image, which is likely not enough to ID. The 400m IR GSD probably won't be much use. The GF4 is an ocean surveillance system, and will likely be used to gauge activity levels, but I doubt it can do the independent tracking that is often claimed.

3. I also think that cloud cover is a huge limitation on EO coverage. It's cloudy a lot in the Pacific. Here's the current aviation sigwx forecast, and you can see that there's typically a decent amount of cloud cover across the entire region.

[Dysta]

Satellites aren't that omnipotent, too many conditions must be met to be effectively used, both normal tracking and military purposes.

*ADD: gosnold you can also add a small addition of failed satellites, such as GF-10.

[gosnold]

ORIGINAL: ExNusquam

Gosnold, this is easily one of the best open-source pieces on Chinese space based ISR, and the implications of that for building a firing solution. I fully concur with you that there are two targeting windows, where there are closely spaced passes by a SAR bird followed by an EO bird. I only have a couple of minor technical points:

1. You asses that if the SAR birds flew in pairs they could do positive ship ID. I doubt this is possible beyond basic dimensions and RCS due to the effects of target motion on SAR. A moving target will be a blurry, smeary mess at high resolution and a slightly less blurry, smeary mess at lower resolution. The streaking in the example of the oil tanker (left) is caused by the relatively small motion of the ships radars; I suspect the ship itself is stationary.

2. I have suspicions about the ability of the GF-4 to effectively track BLUFOR ships. Here's a screenshot from MarineTraffic showing AIS hits just North of the Marianas (inside the second island chain)...there are a lot of vessels out there that will generate sizable wakes. A 50m EO GSD means a Carrier will be 6 piles on a GF4 image, which is likely not enough to ID. The 400m IR GSD probably won't be much use. The GF4 is an ocean surveillance system, and will likely be used to gauge activity levels, but I doubt it can do the independent tracking that is often claimed.

3. I also think that cloud cover is a huge limitation on EO coverage. It's cloudy a lot in the Pacific. Here's the current aviation sigwx forecast, and you can see that there's typically a decent amount of cloud cover across the entire region.

Thanks for the feedback!

Regarding 1., I did not know moving targets are blurry on SAR images, but I looked it up and you are right, the high-resolution images of a fast ship would be deteriorated, making identification more difficult. Now SAR processing is kind of a black art and there might be ways to get rid of the blur if you really need to, so I wouldn't say ship moving ship ID is impossible with SAR.

For 2., I think carrier identification is very feasible with GF-4. If you look for a 330m-long CVN, you are looking for ships 6 to 7 pixels long. That means 300 to 350m, so you have aircraft carriers, oil supertankers and large container ships. The GF-4 sensor gives you colour + IR so you can ignore the ships that are not gray, that reduces the number of candidates considerably. Then you can discriminate on speed: the tankers and container ships rarely go over 20 knots, the carrier is the only one that can go 30 knots. Finally you can discriminate on course: the civilian ships will follow a constant heading, the carrier will change heading to have head-on winds during air operations. With all that I don't think you can mistake the carrier and the civilian ships.

Regarding 3., you are definitely right about that, cloud coverage has a major impact. Do you know a good resources to know cloud coverage over the course of a year? I'm looking for how much time the weather is completely overcast for several days at a time in the region, since that would make optical systems blind.

[magi]

That was very good.... thank you....

[ExNusquam]

ORIGINAL: gosnold

Thanks for the feedback!

Regarding 1., I did not know moving targets are blurry on SAR images, but I looked it up and you are right, the high-resolution images of a fast ship would be deteriorated, making identification more difficult. Now SAR processing is kind of a black art and there might be ways to get rid of the blur if you really need to, so I wouldn't say ship moving ship ID is impossible with SAR.

For 2., I think carrier identification is very feasible with GF-4. If you look for a 330m-long CVN, you are looking for ships 6 to 7 pixels long. That means 300 to 350m, so you have aircraft carriers, oil supertankers and large container ships. The GF-4 sensor gives you colour + IR so you can ignore the ships that are not gray, that reduces the number of candidates considerably. Then you can discriminate on speed: the tankers and container ships rarely go over 20 knots, the carrier is the only one that can go 30 knots. Finally you can discriminate on course: the civilian ships will follow a constant heading, the carrier will change heading to have head-on winds during air operations. With all that I don't think you can mistake the carrier and the civilian ships.

Regarding 3., you are definitely right about that, cloud coverage has a major impact. Do you know a good resources to know cloud coverage over the course of a year? I'm looking for how much time the weather is completely overcast for several days at a time in the region, since that would make optical systems blind.

1. You can get rid of the blurring to a degree by reducing resolution. High-res SAR requires a larger (synthetic) aperture and so the target moves more while this occurs. By using a smaller aperture, the target is less blurry, but at lower resolution.

2. Has it been confirmed that the GF-4 has an MSI payload? The only stuff I've seen was that it was "visible light" which I interpreted as panchromatic. You are correct about the flight ops giving away the carrier, but if BLUFOR refrains from or minimizes displacement from PIM during flight ops, they will be harder to track. Here's an excellent piece (by a former Soviet Naval Officer) about attempting to kill US CVBGs; take note about the part where the Carriers will sail completely independently to confuse targeting.

3. The source I would have recommended would have been the USAF weather site, but for the last couple of years it's required a CAC to access. I'm sure if you look for a marine almanac you can find something; marine and aviation weather forecasting could provide a useful alternative.

[Dysta]

In other word: China will not use these satellites for missile guidance. They are only providing visuals for operators.

[gosnold]

ORIGINAL: Dysta

In other word: China will not use these satellites for missile guidance. They are only providing visuals for operators.

They can definitely be used to give a firing solution to missiles.

ORIGINAL: ExNusquam

1. You can get rid of the blurring to a degree by reducing resolution. High-res SAR requires a larger (synthetic) aperture and so the target moves more while this occurs. By using a smaller aperture, the target is less blurry, but at lower resolution.

2. Has it been confirmed that the GF-4 has an MSI payload? The only stuff I've seen was that it was "visible light" which I interpreted as panchromatic. You are correct about the flight ops giving away the carrier, but if BLUFOR refrains from or minimizes displacement from PIM during flight ops, they will be harder to track. Here's an excellent piece (by a former Soviet Naval Officer) about attempting to kill US CVBGs; take note about the part where the Carriers will sail completely independently to confuse targeting.

3. The source I would have recommended would have been the USAF weather site, but for the last couple of years it's required a CAC to access. I'm sure if you look for a marine almanac you can find something; marine and aviation weather forecasting could provide a useful alternative.

Gaofen-4 does have a colour imager, for instance see
those images of Beijing.

[ExNusquam]

ORIGINAL: gosnold

Gaofen-4 does have a colour imager, for instance see
those images of Beijing.

Thanks for the source on that!

[gosnold]

Henri (from eastpendulum.com) has found a nice report by the Indian National Institute of Advanced Studies on the chinese sats. It mostly agrees with my blog post.

So I went digging in the NIAS website and found a analysis of the Chinese ASBM capability which is worth a read:
http://eprints.nias.res.in/300/1/NIAS_Report_R5-2011.pdf

[Dysta]

ORIGINAL: gosnold

So I went digging in the NIAS website and found a analysis of the Chinese ASBM capability which is worth a read:
http://eprints.nias.res.in/300/1/NIAS_Report_R5-2011.pdf

Interestingly, the report is 5 years old, but I found this line particularly true until now:

Whatever be the combination of measures that the US chooses, it would appear that the ASBM has already achieved part of the intended effect by forcing a re-evaluation of the military equation and injecting an element of uncertainty in what was an unchallenged military scenario for the United States.

Simply say, China force US and it's neighbors to develop ABM systems to encumbering their military budget with substantial margins, right at the decade of economical downfall. DF-21 doesn't need to be terribly effective against land or ships, deterrence is all it need to have, and is doing already.

[gosnold]

For those interested, I found an actual Gaofen-4 image in a presentation from the China Academy of Space technology


I found it while writing an article on persistent surveillance from high orbit:
https://satelliteobservation.wordpress.com/

I also found an interesting piece of information on US satellites: did you know the US missile warning satellites can detect Backfires when they engage their afterburner? They can also detect plane crashes. It would be interesting to model those capabilities in-game.

[Dimitris]

IIRC we already model the DSP sats as being able to detect planes on afterburner. I'll have to double-check what we enable for SBIRS.