Using knowledge of torpedoes gained from her first husband – munitions manufacturer Friedrich Mandl – Antheil and Lamarr developed the idea of using frequency hopping: in this case using a player piano roll to randomly change the signal sent between the control center and torpedo at short bursts within a range of 88 frequencies on the spectrum (88 black and white keys are on a piano keyboard). The specific code for the sequence of frequencies would be held identically by the controlling ship and in the torpedo. This basically encrypted the signal, as it was impossible for the enemy to scan and jam all 88 frequencies because this would have required too much power. Antheil would control the frequency-hopping sequence using a player-piano mechanism, which he had earlier used to score his "Ballet Mécanique".