An impulse signature is a dectectable energy phenomenon produced by impulse-powered vessels.
In 2370, the Maquis utilized an implosive protomatter device to destroy the Bok'Nor, a Cardassian vessel, having matched the device to the ship's impulse signature to avoid detection. (DS9: "The Maquis, Part I")
In 2372, the crew of the USS Defiant detected an impulse signature in the Badlands, signalling the arrival of a Maquis raider which had come to rendezvous with the SS Xhosa, which the Defiant crew had been following under cloak. (DS9: "For the Cause")
In 2375, while searching for the missing Delta Flyer, the crew of the USS Voyager was able to detect the Flyer's impulse signature in the upper atmosphere of a planet on which the shuttle had crashed. (VOY: "Once Upon a Time")
Later that year, the crew of Voyager, who were attempting to transport a group of telepathic refugees to a wormhole in the Tehara system, eluded detection by the scanning pulse of a Devore sensor array designed to dectect warp fields and impulse signatures, by lowering the ship's power output to beneath the array's detection threshold. (VOY: "Counterpoint")
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