What is her contributions to Informatic?

Hedy Lamarr was Austrian naturalized American. She is mainly known for being an actress but she also graduated from the ingegnery faculty of the University of Vienna as an inventor.
Eager to contribute to the fight against Nazism, she developed with the composer George Antheil a remote guidance system for torpedoes, although it didn't gather much attention, a modulation system for coding information on radio frequencies towards an apparatus that received them in the same order in which they had been transmitted. With a simple mechanism based on the insides of a player piano, messages would jump or “hop” from one frequency to another at random, making it impossible to listen in or to jam the signal. Lamarr intended that the system would steer a torpedo remotely, guiding it towards a moving ship with no danger of interference from the enemy.

The principles of their work are incorporated into Bluetooth and GPS technology and are similar to methods used in legacy versions of CDMA and Wi-Fi. This work led to their induction into the National Inventors Hall of Fame in 2014.

Here's a scheme of her patent (n. 2 292 387)

webography:
www.w3schools.com/html
en.wikipedia.org/wiki/Hedy_Lamarr
www.girlstech.it/hedy-lamarr-la-diva-del-cinema-che-invento-il-wi-fi