That was a hard one; very obscure.
Okay. Here is a hard one, then. BUT, it was reported in the news.
This caused a lot of problems for Amateur Radio operators, and OTHER people in radio communications (incl. professionals), off and on from the mid 1970's to the late 1980's.
(I actually worked on the "case"... so to speak... that is, it impacted on my job, and we helped to analyze and characterize the thing).
It has a nickname... two words... a nationality and a bird.
However, if a SPECIFIC answer isn't guessed / found by anyone, I'll answer for a good GENERAL guess. I've already provided a clue (" ... caused a lot of problems ... "), but no, it is NOT a jammer.
EDIT:
And no, it does not detect UFO's/Flying Saucers, or evil laser jellyfish.