Impulsive emanations are signals emitted from an information processing device that are being compromised or can be intercepted. This is a type of compromised emanation (CE) and is considered a part of Telecommunications Electronics Material Protected from Emanating Spurious Transmissions (TEMPEST). Impulsive emanations are found in most equipment that processes digital data.
Techopedia explains Impulsive Emanations
Impulsive emanations are generally formed with electrical equipment that is being tested. It demonstrates that whatever an individual is doing on a computer can be seen on another computer as the emanated signals are broadcast into the air and can be easily intercepted. Impulsive emanations are caused when the equipment under test (EUT) processes digital signals very quickly.