China integrates long-range surveillance capabilitiesChina integrates long-range surveillance capabilities ... a Long March 2C rocket was launched from China’s Xichang Satellite

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China integrates long-range surveillance capabilities

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As China seeks to expand its control over its maritime approaches and to operate further

afield, it has developed its space- and ground-based long-range surveillance capabilities.

Andrew Tate looks at these assets and considers the capabilities that they deliver.

On 29 September, a Long March 2C rocket was launched from China’s Xichang Satellite Launch

Centre, carrying three Yaogan surveillance satellites. These are further additions to China’s array

of long-range surveillance assets, which has increased and improved dramatically since 2006.

China's long-range surveillance capabilities. (IHS Markit)

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China has a strategic need for surveillance of its seaward approaches for national defence and to

underpin its goal of exerting sea control in its exclusive economic zone (EEZ), which would expand

vastly if China’s claims in the South China Sea were to be established. Geography does not favour

China, as the air and sea routes to the open waters of the west Pacific are obstructed by the ‘first

island chain’, which includes the Japanese archipelago, Taiwan, the northern Philippines, and

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consent, with the exception of any internal client distribution as may be permitted in the license agreement between client and IHS. Content reproduced or redistributed with IHS permission must display IHS legal notices and attributions of authorship. The

information contained herein is from sources considered reliable but its accuracy and completeness are not warranted, nor are the

opinions and analyses which are based upon it, and to the extent permitted by law, IHS shall not be liable for any errors or

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Borneo. Taiwan is a little over 100 km offshore and other islands a few hundreds of kilometres.

This contributes to Chinese perceptions of being constrained and hemmed in by potential

adversaries.

To support its current military posture and principal area of operations, China needs to be capable

of achieving air, surface, and sub-surface surveillance in the East China Sea, the South China

Sea, the Philippine Sea, and into the west Pacific. As its carrier force grows and starts to operate

outside these areas, coverage is likely to expand to include the Sea of Japan and Indian Ocean.

The requirement spans not only the capability to be alerted to ships and aircraft approaching the

areas that China wishes to control, but also the tactical need for targeting data to support its large

inventory of long-range anti-ship cruise missiles (ASCMs), as well as anti-ship ballistic missiles

(ASBMs).

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Over the horizon

A system that can provide long-range, 24/7 coverage is over-the-horizon (OTH) radar, and China

is one of very few countries to have developed such systems. Conventional radar coverage is

limited by the horizon – the point at which the curvature of the Earth prevents radar waves,

travelling in straight lines, being able to reflect off a distant object. This distance depends upon the

height of the transmitting array and the height of the contact, so a large warship may be able to

detect another at around 50 km, whereas an airborne radar at an altitude of 10,000 m may be able

to detect a surface contact at approximately 200 km.

OTH radar can achieve much longer range detections by exploiting circumstances in which the

electromagnetic waves emitted by the radar are reflected by the ionosphere in Earth's upper

atmosphere, rather than passing through it. This backscattering (B) effect requires the OTH-B

radar to use frequencies in the high frequency (HF) band (3–3MHz) – much lower than most

radars – and as it must transmit at high power and detect very small return signals, it requires very

large arrays. Typically these arrays are a few hundred metres in length for the transmitter array

and 2–3 km for the receiver array, so they are identifiable on satellite imagery given an

approximate location. To avoid self-interference, the two arrays are sited at least 100 km apart.

Around 2008, China constructed a transmitter array located at 32.34N, 112.70E, with the

corresponding receiver array at 31.62N, 111.91E. These sites are approximately 1,000 km inland

(see map), which corresponds to the expected distance between the transmitter and the point at

which the signal reflected by the ionosphere bounces back to the Earth’s surface. Coverage can

be expected to be from the Chinese coast to approximately 2,500 km beyond, over an arc of about

60 degrees, centred on a bearing of 120 degrees. This provides coverage deep into the west

Pacific, to within a few hundred kilometres of Guam.

Operating an OTH-B radar is, however, significantly more challenging than a conventional radar.

Its performance depends on the characteristics of the ionosphere, which are constantly changing.

Consequently, there is a need for ionospheric soundings that enable the transmissions to be

adjusted to maximise the reflection. China has built a number of sites around the coast that

perform this function, and these must be linked back to the transmitter.

The OTH-B radar transmits a frequency modulated continuous wave (FMCW) and uses doppler

shifts to identify contacts within the scanned arc. The combination of the distances involved,

relatively long wavelength, and atmospheric variability limit the accuracy that can be achieved both

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information contained herein is from sources considered reliable but its accuracy and completeness are not warranted, nor are the

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in range and bearing; Jane's estimates that the system could yield a position within a 10-km radius

of uncertainty.

[Continued in full version…]

An aerial view of Sansha city on Woody Island in the Paracels taken on 27 July 2012. China has deployed radar systems to features that it controls in the South China Sea; its OTH radar coverage is focused on the waters east of the Philippines in the Pacific. (STR/AFP/Getty Images)

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Overhead assets

According to the US-based Union of Concerned Scientists, China has 192 satellites in orbit,

second only to the US which has 593 (Russia has 135). This data include launches through to the

end of 2016, meaning that the actual figures will be higher. It is not possible to be certain about the

function of all China’s satellites, as most are operated by government agencies and a number are

likely to be dual-use.

Nonetheless, although the functions of the Yaogan Weixing (remote sensing) satellites are often

given as land resource surveys, crop yield studies, scientific research, and disaster relief, there is

a consensus among security analysts that the role of the Yaogan satellites is military intelligence,

surveillance, and reconnaissance (ISR). Including the three launched in September 2017, there

are currently 35 Yaogan satellites in orbit, providing electro-optical and infra-red (EO/IR) imaging,

synthetic-aperture radar (SAR), and electronic intelligence (ELINT) capabilities.

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consent, with the exception of any internal client distribution as may be permitted in the license agreement between client and IHS. Content reproduced or redistributed with IHS permission must display IHS legal notices and attributions of authorship. The

information contained herein is from sources considered reliable but its accuracy and completeness are not warranted, nor are the

opinions and analyses which are based upon it, and to the extent permitted by law, IHS shall not be liable for any errors or

omissions or any loss, damage or expense incurred by reliance on information or any statement contained herein.

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China’s first in-service aircraft carrier, Liaoning , arrives in Hong Kong waters on 7 July 2017, less than a week after a high-profile visit by Chinese President Xi Jinping. As China’s carrier force grows and starts to operate further afield, its long-range surveillance requirements are likely to expand to include the Sea of Japan and the Indian Ocean. (Anthony Wallace/AFP/Getty Images)

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Although the function and capabilities of Chinese satellites may not be officially stated, significant

inferences can be drawn from such attributes as the launch vehicle used and the parameters of

the satellite’s orbit – a satellite with a SAR payload will be substantially heavier than an EO/IR

platform, requiring a heavier launch vehicle, and a 35,000-km geostationary orbit will suit a

communications satellite, but not one for high-resolution imaging.

In order to reduce the interval between the times when a satellite passes over an area of interest,

additional satellites can be placed in similar orbits, ideally distributed evenly around the globe so

that the interval between passes is roughly constant. These satellites may be grouped together by

function and technology used. The People’s Liberation Army (PLA) is generally assessed to group

these under the nomenclature Jian Bing (JB), but as this designator is not generally used in open

sources there can be some uncertainty about which group encompasses specific satellites.

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consent, with the exception of any internal client distribution as may be permitted in the license agreement between client and IHS. Content reproduced or redistributed with IHS permission must display IHS legal notices and attributions of authorship. The

information contained herein is from sources considered reliable but its accuracy and completeness are not warranted, nor are the

opinions and analyses which are based upon it, and to the extent permitted by law, IHS shall not be liable for any errors or

omissions or any loss, damage or expense incurred by reliance on information or any statement contained herein.

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Identification of Chinese OTH-B radar signal. (© 2017 IHS Markit)

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The most numerous of the Yaogan surveillance platforms are the 18 satellites believed to have an

ELINT function, the majority of which are grouped as Jian Bing 8 (JB-8). The large number is a

consequence of their being placed in orbit as triplets in close proximity. It is likely that these triplets

are tasked with detecting electromagnetic emissions (such as radar) and determining the

geographic location of the source by triangulation, based on the time difference of arrival (TDOA)

at each of the satellites.

Work done by Subrahmanyan Chandreshakar and others at the National Institute of Advanced

Studies in Bangalore in 2011, drawing on the characteristics of the US Naval Ocean Surveillance

System (NOSS) satellites, suggests that the radius of coverage of each triplet would be

approximately 3,500 km. The JB-8 satellites are in similar orbits at approximately 1,100 km and 63

degrees inclination, and multiple triplets potentially provide global coverage with revisit times of

three hours or less. The most recent additions (Yaogan 30-1 A, B, and C) are at a lower inclination

of 35 degrees and altitude of 600 km, which may increase the probability of detecting an emission

and improve the accuracy of geolocation in the critical areas of the first island chain and the west

Pacific.

The non-ELINT Yaogan satellites have all been placed in near-polar, sun-synchronous orbits. This

is achieved by choosing the orbit inclination and height so that the time taken to complete one orbit

equals the time-shift due to the Earth’s rotation at any latitude. Consequently, the satellite crosses

any given latitude at the same local time on the surface at each pass, and the local time of passing

overhead at the equator readily defines the spacing of the orbits.

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consent, with the exception of any internal client distribution as may be permitted in the license agreement between client and IHS. Content reproduced or redistributed with IHS permission must display IHS legal notices and attributions of authorship. The

information contained herein is from sources considered reliable but its accuracy and completeness are not warranted, nor are the

opinions and analyses which are based upon it, and to the extent permitted by law, IHS shall not be liable for any errors or

omissions or any loss, damage or expense incurred by reliance on information or any statement contained herein.

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Analysis of Chinese OTH-B radar signal. (© 2017 IHS Markit)

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Jane's assesses that China is likely to have six military surveillance satellites in sun-synchronous

orbit carrying synthetic aperture radar. Four are at an altitude of 500 km and form the JB-7

constellation. The other two are slightly higher at 630 km, so may be part of a different Jian Bing

cluster. These SAR satellites descend over the equator at around 0200, 0430, 0600, and 1000

(and ascend 12 hours later), so the maximum interval between SAR passes is four hours.

Based on the performance of civilian Chinese SAR satellites, such as Gaofen 3, the swath imaged

by the military SAR sensor is probably selectable, and may be of the order of a broad 100-km

swath at 20-m resolution to a narrow 10-km swath at a resolution of 1.5 m. These swaths are

significantly less than the 2,750-km step between successive orbital passes, but it is possible that

the antenna of the SAR sensor is trainable, so that if cued by either OTH-B radar or an ELINT

satellite, it could be directed to cover the longitude of a contact of interest.

The JB-9 constellation appears to comprise five satellites (Yaogan 8, 15, 19, 22, and 27) in a sun-

synchronous orbit that pass overhead at about 0930, 1030, 1330, and 1430. The close interval

between passes during daylight suggests that these are for optical imaging, and the 1,200-km orbit

height indicates that they have a relatively wide field of view, with resolution in the bracket of 3–10

m.

[Continued in full version…]

Command and control

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consent, with the exception of any internal client distribution as may be permitted in the license agreement between client and IHS. Content reproduced or redistributed with IHS permission must display IHS legal notices and attributions of authorship. The

information contained herein is from sources considered reliable but its accuracy and completeness are not warranted, nor are the

opinions and analyses which are based upon it, and to the extent permitted by law, IHS shall not be liable for any errors or

omissions or any loss, damage or expense incurred by reliance on information or any statement contained herein.

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It is evident that to provide comprehensive surveillance using the long-range detection systems

reviewed, the monitoring and control of the different systems need to be co-ordinated, at a

minimum, and ideally, integrated. This will require inter-service co-operation or joint (land, naval,

and air forces) operation, an activity that has not traditionally been a strength of the Chinese

armed forces.

There is very little publicly available information about the organisational structures set up to

achieve this. Furthermore, these are likely to have changed following the drive by President Xi to

make joint force integration a reality rather than a rhetorical concept. The change from the

organisational structures of seven military regions to five theatre commands in early 2016 was a

significant step in this process of change, as was the creation of the PLA Strategic Support Force

(PLASSF).

A military vehicle carries a DF-21D missile past a display screen featuring an image of the Great Wall of China at Tiananmen Square in Beijing on 3 September 2015. To target the DF-21D effectively will require China to integrate multiple forms of long-range surveillance in a timely fashion. (Greg Baker/AFP/Getty Images)

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Operation of the OTH-B radars was previously the responsibility of the People’s Liberation Army

Air Force (PLAAF), and may still be, although the PLASSF is now assessed to be responsible for

satellite operations. It is not clear whether operation of the ballistic missile defence (BMD) radars

falls to the PLA Rocket Force (PLARF), the PLAAF, or the PLASSF. Should long-range

surveillance lead to the targeting of long-range weapons, close co-ordination with the PLARF will

be required if this involves anti-ship ballistic missiles, such as the DF-21D or DF-25, and with the

PLA Navy (PLAN) if anti-ship cruise missiles, launched from submarines or surface ships, are to

be used.

[Continued in full version…]

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consent, with the exception of any internal client distribution as may be permitted in the license agreement between client and IHS. Content reproduced or redistributed with IHS permission must display IHS legal notices and attributions of authorship. The

information contained herein is from sources considered reliable but its accuracy and completeness are not warranted, nor are the

opinions and analyses which are based upon it, and to the extent permitted by law, IHS shall not be liable for any errors or

omissions or any loss, damage or expense incurred by reliance on information or any statement contained herein.

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Ballistic missile tracking radars Overhead imagery shows that China has four ground-based large phased-array radars (LPARs), located near Huanan (46.53N, 130.76E), near Yiyuan (36.02N, 118.09E), near Hangzhou (30.29N, 119.13E), and near Korla (41.64N, 86.24E). Apart from their location, very little information is available from open sources about these LPARs, particularly regarding their function. Each has a single array face of approximately 30 m diameter and coverage is likely to be over an arc of 90–120 degrees. A Chinese television report on 8 October suggested that at least one, the LPAR near Yiyuan, transmits on frequencies in P-band (225–390 MHz), with an estimated maximum detection range of 4,000 km. They are similar in appearance to US Pave PAWS ballistic missile early warning system (BMEWS) radars, and tracking ballistic missiles in flight is likely to be a primary function. However, the alignment of the radars suggests that coverage may not match the most likely ballistic missile threat directions. The Yiyuan and Hangzhou radars are both aligned in a southeasterly direction, giving good coverage of the East and South China Seas, a low ballistic missile threat axis other than the small number of Taiwanese conventionally armed tactical BM. Although speculative, one possibility is that at least one of these radars might be associated with tracking, command, and control of China’s DF-21D and DF-25 anti-ship ballistic missiles. The array faces of these two radars are different (Yiyuan is circular, Hangzhou octagonal), so they may have different transmission or functional characteristics.

[Continued in full version…]

Satellite coverage The height that a satellite orbits above the Earth’s surface is a key factor in determining the footprint of the satellite’s sensors and consequently the extent covered by surveillance, as well as the accuracy with which the position of an object on the Earth’s surface can be determined. Geopositional accuracy of a contact improves if the satellite is placed in a lower orbit, but at the expense of covering a narrower swath around the globe. Furthermore, at very low altitudes a satellite is subject to the drag of the Earth’s atmosphere, which would progressively reduce its speed and result in it falling out of orbit. Consequently, most surveillance satellites, which are designed to remain operational for years, are placed in a low-earth orbit (LEO) at an altitude of approximately 500–1,000 km. For any given altitude, the speed at which the satellite must travel if it is to remain in orbit is fixed by the force exerted by the Earth’s gravity – the higher the orbit, the less pull that gravity exerts and the slower the satellite must travel if it is to remain in orbit. In turn, the satellite’s velocity determines the time taken to complete an orbit, which for a satellite at a height of 1,000 km takes about 100 minutes. In this trajectory, the satellite completes about 14 orbits every 24 hours, during which time the earth is rotating beneath it. On each pass the satellite will appear to have moved a distance of 2,750 km at the equator, stepping around the globe over subsequent orbits. The satellite will pass over any region under its path twice per day, once when travelling from south to north (ascending) and about 12 hours later travelling from north to south (descending).

[Continued in full version…]

On the web China reorients strategic military intelligence Chinese naval intelligence fleet expands Final frontier – China’s emerging military-space architecture

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consent, with the exception of any internal client distribution as may be permitted in the license agreement between client and IHS. Content reproduced or redistributed with IHS permission must display IHS legal notices and attributions of authorship. The

information contained herein is from sources considered reliable but its accuracy and completeness are not warranted, nor are the

opinions and analyses which are based upon it, and to the extent permitted by law, IHS shall not be liable for any errors or

omissions or any loss, damage or expense incurred by reliance on information or any statement contained herein.

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Author Andrew Tate is a former UK Royal Navy officer and naval and air attaché at the British Embassy in Beijing.

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