Abstract: A method of monitoring the temperature of a target (4), the method comprising:a) sensing radiation emitted by the target (4) at at least two different wavelengths;b) determining a temperature value from the sensed radiation in accordance with a first predetermined algorithm;c) repeating steps a) and b) a number of times to generate a set of temperature values;d) selecting a target temperature from the set of temperature values in accordance with a second predetermined algorithm; and,e) generating an output signal defining the target temperature obtained in step d).

Abstract: The invention is concerned with a burner monitor comprising a variator which is arranged to cause a predetermined fluctuation of the flow of a reactant to a burner to cause flickering of the burner flame. A detector for radiation from the flame from the burner emits a signal corresponding to the radiation. A comparator assesses the polarity of any correlation between the applied fluctuations and the signal from the detector and an indicator indicates the assessed polarity. The output from the indicator may be integrated to produce a quantitative assessment of the fuel rich or fuel lean flame condition.