Fiber optic personnel safety systems and methods of using the same
A personnel monitoring system. The personnel monitoring system includes a host node having an optical source for generating optical signals, and an optical receiver. The personnel monitoring system also includes a plurality of fiber optic sensors for converting at least one of vibrational and acoustical energy to optical intensity information, each of the fiber optic sensors having: (1) at least one length of optical fiber configured to sense at least one of vibrational and acoustical energy; (2) a reflector at an end of the at least one length of optical fiber; and (3) a field node for receiving optical signals from the host node, the field node transmitting optical signals along the at least one length of optical fiber, receiving optical signals back from the at least one length of optical fiber, and transmitting optical signals to the optical receiver of the host node.
1. A method of operating a personnel monitoring system comprising:
(a) storing a plurality of predetermined characteristics of events to be monitored using an optical detection system in memory;
(b) comparing a detected characteristic obtained from the optical detection system to the plurality of predetermined characteristics stored in memory; and
(c) determining if there is an acceptable level of matching between the detected characteristic and at least one of the plurality of predetermined characteristics stored in memory,
wherein, if it is determined that there is an acceptable level of matching at step (c), the method further comprises the step of (d) determining if the acceptable level of matching is present for a predetermined period of time in a closed loop configuration wherein a counter is updated for each incremental time period during which there is an acceptable level of matching.
2. The method of claim 1 further comprising the step of generating an alarm condition if it is determined that there is an acceptable level of matching at step (c).
3. A method of operating a personnel monitoring system comprising:
(a) storing a plurality of predetermined characteristics of events to be monitored using an optical detection system in memory;
(b) comparing a detected characteristic obtained from the optical detection system to the plurality of predetermined characteristics stored in memory; and
(c) determining if there is an acceptable level of matching between the detected characteristic and at least one of the plurality of predetermined characteristics stored in memory,
wherein, if it is determined that there is an acceptable level or matching at step (c), the method further comprises the step of (d) determining if the acceptable level of matching is present for a predetermined period of time,
further comprising the step of generating an alarm condition if it is determined that the acceptable level of matching is present for a predetermined period of time in step (d),
wherein step (a) Includes: (a1) applying a windowing function to a sampled set of data points within a series of time windows during a series of known events; (a2) creating a spectrum by applying a Fast Fourier Transform (FFT) to the set of data points to which the windowing function has been applied; (a3) scaling the spectrum to Include a population of system responses to a series of similar events to create a spectral mask; (a4) associating the spectral mask with each of the series of known events; and (a5) storing the associated spectral mask in a data structure accessible by the optical detection system.
4. The method of claim 3 wherein step (b) Includes: (b1) acquiring windowed samples of data during operation of the optical detection system; (b2) generating spectra of the windowed samples of data as a function of time; and (b3) comparing the spectra generated in step (b2) to the spectral mask stored in step (a5) of step (a).