A method to determine actual locations of electrical devices from which radio signals are received comprising: obtaining, from a sensing device at a first time, first information corresponding to a radio signal received at the sensing device from a candidate location, wherein the sensing device is at a first location in its movement trajectory at the first time; obtaining, from the sensing device at a second time, second information corresponding to a radio signal received at the sensing device from the candidate location, wherein the sensing device is at a second location in its movement trajectory at the second time; characterised in determining that a known pattern is present in each of the first information and the second information; conditioned on determining that the known pattern is present in each of the first information and the second information: determining a first relationship between the candidate location and the sensing device at the first location, and a second relationship between the candidate location and the sensing device at the second location; obtaining a first inverse of the first relationship and a second inverse of the second relationship; determining a first estimate of the radio signal received at the sensing device from the candidate location based on the first information and the first inverse, and a second estimate of the radio signal received at the sensing device from the candidate location based on the second information and the second inverse; and determining an estimate of an energy emitted from the candidate location based on the first estimate and the second estimate. obtaining, from a sensing device at a first time, first information corresponding to a radio signal received at the sensing device from a candidate location, wherein the sensing device is at a first location in its movement trajectory at the first time; obtaining, from the sensing device at a second time, second information corresponding to a radio signal received at the sensing device from the candidate location, wherein the sensing device is at a second location in its movement trajectory at the second time; characterised in determining that a known pattern is present in each of the first information and the second information; conditioned on determining that the known pattern is present in each of the first information and the second information: determining a first relationship between the candidate location and the sensing device at the first location, and a second relationship between the candidate location and the sensing device at the second location; obtaining a first inverse of the first relationship and a second inverse of the second relationship; determining a first estimate of the radio signal received at the sensing device from the candidate location based on the first information and the first inverse, and a second estimate of the radio signal received at the sensing device from the candidate location based on the second information and the second inverse; and determining an estimate of an energy emitted from the candidate location based on the first estimate and the second estimate. determining a first relationship between the candidate location and the sensing device at the first location, and a second relationship between the candidate location and the sensing device at the second location; obtaining a first inverse of the first relationship and a second inverse of the second relationship; determining a first estimate of the radio signal received at the sensing device from the candidate location based on the first information and the first inverse, and a second estimate of the radio signal received at the sensing device from the candidate location based on the second information and the second inverse; and determining an estimate of an energy emitted from the candidate location based on the first estimate and the second estimate.