Localisation of a signal emitting source
AssigneeQinetiq Limited
InventorWieslaw J. Szajnowski
Life of this patent
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Abstract
A source localising method comprises the steps of measuring the power received by a set of sensors and selecting N measurements from respective sensors, where N is an even number and at least four. N−1 different direct power ratios are constructed each derived from the N power measurements, with different numerators and denominators derived from respective halves of the measurements in each case. The construction of N−1 direct power ratios is facilitated by the use of a suitably constructed Hadamard matrix. Each direct power ratio may be converted with a logarithmic transformation into a linear combination of measured powers.
Claims13
A method of locating a signal emitting source comprising the steps of:
- a) making measurements of power received from the source by a set of sensors and selecting N such measurements from respective sensors, where N is an even number and at least four;
- b) constructing N−1 direct power ratios each derived from the N power measurements, each ratio having a numerator which is the product of a respective sub-set of N/2 of the N power measurements and a denominator which is the product of the N/2 outside such sub-set in each case;
- and
- c) calculating the source location from the direct power ratios.
A method as claimed in claim1 wherein the location of the signal emitting source is calculated by:
- c) calculating predicted power ratios for each of a plurality of hypothesized source locations;
- d) comparing the direct power ratios with the predicted power ratios;
- and
- e) identifying the hypothesized source location having the smallest discrepancy between the predicted power ratios and the direct power ratios.
A method as claimed in any preceding claim wherein each direct power ratio is converted with a logarithmic transformation into a linear combination of measured powers.
A method of as claimed in any preceding claim wherein the source is emitting an electromagnetic or acoustic signal.
A method as claimed in preceding claim, wherein the signal emission is continuous, intermittent or pulsed.
A method as claimed in any preceding claim wherein the N sensors are produced by moving one or more sensors in a suitable manner and determining the sensor positions.
A method to locate a signal emitting source substantially as hereinbefore described with reference to FIGS. 2 to 5 of the accompanying drawings.
A system for locating a signal emitting source comprising:
- a) a set of sensors for making measurements of power received from the source;
- b) means for selecting N power measurements from respective sensors, where N is an even number not less than four;
- c) means for constructing N−1 direct power ratios each derived from the N power measurements, each ratio having a numerator which is the product of a respective sub-set of N/2 of the N power measurements and a denominator which is the product of the N/2 power measurements outside such sub-set in each case;
- and
- d) means for calculating the source location from the direct power ratios.
A computer program for use in locating a signal emitting source and arranged to control a computer to carry out the steps of:
- a) receiving measurements of power received from the source by a set of sensors;
- b) selecting N such power measurements from respective sensors, where N is an even number not less than four;
- c) constructing N−1 direct power ratios each derived from the N power measurements, each ratio having a numerator which is the product of a respective sub-set of N/2 of the N power measurements and a denominator which is the product of the N/2 power measurements outside such sub-set in each case;
- and
- d) calculating a location of the signal emitting source from the direct power ratios.
A system for locating a signal emitting source comprising a set of sensors responsive to the source and computer apparatus arranged to receive measurements of power received from the source by the sensors, the apparatus being programmed to carry out the steps of:
- a) selecting N power measurements from respective sensors, where N is an even number not less than four;
- b) constructing N−1 direct power ratios each derived from the N power measurements, each ratio having a numerator which is the product of a respective sub-set of N/2 of the N power measurements and a denominator which is the product of the N/2 power measurements outside such sub-set in each case;
- and
- c) calculating the source location from the direct power ratios.
Dependencies are inferred from the claim text.