Method and system for video processing to determine digital pulse recognition tones

A method for isolating a broadcast digital pulse recognition tone of a beacon light source in a digital video sequence, the method comprising:

• electronically receiving, by an image sensor of a mobile device, a digital video sequence of a scene, wherein the digital video sequence comprises a sequence of frames and the scene comprises both modulated illumination broadcast by a beacon light source and un-modulated illumination;
• calculating a background value of the digital video sequence, wherein the background value comprises a portion of the digital video sequence corresponding to the un-modulated illumination of the scene;
• subtracting the background value of the digital video sequence from the digital video sequence to obtain an isolated digital video sequence of the modulated illumination of the scene;
• calculating a frequency content of a frame of the isolated digital video sequence;
• and
• determining a particular symbol broadcast by the beacon light source based on the frequency content;
• wherein each frame of the sequence of frames comprises a plurality of pixel values, each of the plurality of pixel values having a given point in the frame, and calculating the background value comprises analyzing the plurality of pixel values of each given point of a subset of the sequence of frames.