System and method for identifying a muzzle blast using a multi-sensor total energy approach
View Patent ↗Systems and methods for locating the shooter of supersonic projectiles are described. The system uses at least five, preferably seven, spaced acoustic sensors. Sensor signals are detected for shockwaves and muzzle blast, wherein muzzle blast detection can be either incomplete coming from less than 4 sensor channels, or inconclusive due to lack of signal strength. Shooter range can be determined by an iterative computation and/or a genetic algorithm by minimizing a cost function that includes timing information from both shockwave and muzzle signal channels. Disambiguation is significantly improved over shockwave-only measurements.
1. A method for identifying a muzzle blast within a signal generated by an array of acoustic sensors forming an antenna, comprising:
defining, by a processor, a width for a time window corresponding to a time required for the muzzle blast to traverse the array of acoustic sensors;
detecting, by the processor, a shockwave within the generated signal;
after detecting the shockwave, measuring, by the processor, total energy of the generated signal in a series of consecutive time windows as a function of time and as a function of the number of acoustic sensors that generated the signal, wherein each time window has the defined width;
identifying, by the processor, one of the consecutive time windows having a maximum measured total energy relative to each of the remainder of the consecutive time windows; and
associating, by the processor, the identified time window as corresponding to the muzzle blast.
2. The method of claim 1 , wherein measuring the total energy includes the processor integrating the measured energy over the window and over the number of acoustic sensors.
3. The method of claim 1 , further including identifying, by the processor, shockwave echoes and disregarding windows in the generated signal corresponding to the identified shockwave echoes.
4. The method of claim 1 , further including:
determining, by the processor, a point corresponding to a peak energy in the identified time window; and
associating, by the processor, the point with the muzzle blast if the peak energy at the point is greater than a measured total energy of the remainder of the points in the identified time window by a given ratio factor.
5. The method of claim 4 , further including
performing, by the processor, a cross-correlation across acoustic sensors signals that generated the signal in a muzzle blast frequency band corresponding to the muzzle blast to determine a set of muzzle blast time differences of arrival (TDOA) measurements.
6. The method of claim 5 , wherein the muzzle blast frequency band is between approximately 700 Hz and approximately 10 kHz.
7. The method of claim 1 , further including the processor using the muzzle blast to detect a shooter location.
8. A system for identifying a muzzle blast within a signal generated by an array of acoustic sensors forming an antenna, comprising:
a plurality of acoustic sensors for generating the signal;
a processor configured to:
define a width of a time window corresponding to a time required for a muzzle blast to traverse the array of acoustic sensors;
detect a shockwave within the generated signal;
responsive to the detection of the shockwave, measure total energy in a series of consecutive time windows as a function of time and as a function of the number of acoustic sensors that generated the signal, wherein each time window has the defined width;
identify one of the consecutive time windows having a maximum measured total energy relative to each of the remainder of the consecutive time windows; and
associate the identified time window as corresponding to the muzzle blast.
9. The method of claim 1 , wherein the number of acoustics sensors that generated the signal is greater than one.
10. The method of claim 1 , wherein the measured total energy is the total energy received from multiple acoustic sensors.
11. The system of claim 8 , wherein the number of acoustic sensors that generated the signal is greater than one.
12. The system of claim 8 , wherein the measured total energy is the total energy received from multiple acoustic sensors.