Self-identifying one-way authentication method using optical signals

A method for broadcasting from a light source a pulse width modulated signal, wherein the pulse width modulated signal is converted from an analog signal, the method comprising:

• selecting a carrier frequency, wherein the carrier frequency comprises a repeating interval of time;
• for each interval of time, determining a pulse width by sampling the amplitude of the analog signal and setting the pulse width as a proportion of the interval of time, wherein the proportion of the interval of time is equal to the proportion of the amplitude to a maximum amplitude of the analog signal;
• and
• broadcasting, from the light source, pulses corresponding to the determined pulse widths.

A method for increasing bandwidth of a signal transmitted using a light-based communication system, the method comprising:

• modifying a software setting of an image sensor of a mobile device, wherein the modified software setting increases the signal-to-noise ratio of light-based communication received by the mobile device;
• receiving, at the mobile device using the image sensor, a digital image of a modulated light signal broadcast by a light source, wherein the modulated light signal comprises information related to the broadcasting light source;
• taking a Fourier transform of the digital image to calculate a Fourier transformed signal;
• and
• determining the information related to the broadcasting light source based on the Fourier transformed signal.