Localization systems and methods for an ingestible device

A method for determining a location of an ingestible device within a gastrointestinal tract of a body, the method comprising:

• transmitting a first illumination at a first wavelength and a second illumination at a second wavelength towards an environment external to a housing of the ingestible device;
• detecting a first reflectance from the environment resulting from the first illumination and a second reflectance from the environment resulting from the second illumination, wherein the first reflectance value is indicative of an amount of light in the first reflectance, and the second reflectance value is indicative of an amount of light in the second reflectance;
• storing a ratio of the first reflectance value and the second reflectance value in a data set, the data set including a plurality of values, each of the plurality of values corresponding to a respective ratio of a respective first reflectance and a respective second reflectance detected at a respective time;
• obtaining, from the data set, a first subset of values, the first subset of values corresponding to a first predetermined number of recent measurements;
• obtaining, from the data set, a second subset of values, the second subset of values corresponding to a second predetermined number of past measurements, the recent measurements being taken at a recent time range that is separated from a past time range when the past measurements were taken by at least a predetermined period of time;
• and
• identifying a change in the location of the ingestible device within the gastrointestinal tract of the body when a difference between a first mean value of the first subset of values and a second mean value of the second subset of values exceeds a threshold value.