SIGINT(Signal Intelligence) satellite is used to detect, intercept a nd locate electromagnetic(EM) signals radiated by systems such as ground radar, communication and TT&C systems.

信号情报侦察卫星用于侦收地面雷达、通信和测控等系统所辐射的电磁信号并对其 定位，是航天侦察的重要手段。

youdao

As he describes the Clinton team's evolution from relative impotence in Bosnia during its early months to dynamic involvement in 1995, Mr Halberstam gives a sympathetic hearing to the foreign-service officers who protested strongly because America seemed to be condoning Serb atrocities, about which the United States, with its signal and satellite intelligence, was uniquely well informed.

ECONOMIST: Washington chronicle

Staff tell an apocryphal-sounding anecdote from the Search for Extraterrestrial Intelligence, when a promising signal turned out be a technician warming his lunch at the Arecibo Observatory in Puerto Rico.

BBC: Aye to the telescope

Amos Yadlin, a former head of Israel's military intelligence, said the strike is a signal to Syria's ally, Tehran, that Israel is serious about the red lines it has set.

NPR: Israeli Warplanes Strike Syria In Escalation