China launched three more Yaogan-30 remote-sensing satellites from the Xichang Satellite Launch Centre in southwestern China on 26 July, according to a report by the state-owned Xinhua news agency.
The report said that the satellites, which were placed into orbit by a Long March-2C carrier rocket, will be mainly used for electromagnetic detection and "related technological tests".
The Yaogan-30 satellites are widely believed to be designed for military signals intelligence (SIGINT) purposes and can geo-locate military platforms, particularly warships, by intercepting electromagnetic transmissions such as radar.
The satellites are operated as triplets, positioned in relatively close proximity, that can measure the angular or time difference of arrival of intercepted signals, from which the position of the source can be determined.
The satellites have been positioned in a low-Earth orbit with an altitude of 600 km and inclination of 35°.
The first four groups of Yaogan-30 triplets were launched over a four-month period, from September 2017 to January 2018. The launch of the latest group increases the number of satellites in the constellation to 15.
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