Slitherine

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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.

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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.

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ORIGINAL: Dysta

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

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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.

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ORIGINAL: gosnold

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

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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

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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.

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ORIGINAL: ExNusquam
Sunburn, last I checked the DSP satellites aren't actually importable (the platform exists, though). I just assumed this was just due to the fact that the actual longitudes of the birds being classified. Additionally, the SBIRS birds in game have extremely limited detection capabilities. They don't seem to detect lauches, and the IR sensor they have has a detection range of only 2000NM, which means that anything beyond 33°N/S is undetectable to them from geostationary orbit. Additionally, the launch detection doesn't seem to work well. Try running the attached save.

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ORIGINAL: mikmyk

Hi Guys

Thanks for all the info. I've been looking through our Chinese sat orbat and there is some work to be done. Public info is a pita btw. The Gaofen-4 is supposed to be in a geostationary orbit over Singapore more or less but public orbital data doesn't have it near there. We'll do our best to rectify this but we can only work with what we have and unfortunately we need better data on some.

We've got one critical issue that needs to be solved in that we don't yet define the area that a sat can see. We just do slant range, zoom detection and zoom classification. So the result is a very high sat with values that can see to the ground will also be able to see a very large swarth of territory which isn't quite right. We know what the issue is and are working on a solution.

The next phase at some point will be looking at is focus. Sats don't just see thing but people have to be looking for something in the imagery they produce so we've got to refine that logic a little more. We're thinking about that as well.

Thanks!

Mike