 Pedersen, a famous Danish engineer and physicist, and Brüel was handpicked by Pedersen to work with him.Brüel later described Pedersen as brilliant, but that he took credit for Brüel's and his other students' work.In January 1939, Brüel was drafted into the Danish army to do the radio for the military for a year, and it was there he built his first instrument, a battery-operated, constant-percentage bandwidth analyzer.