RELSEN

The RELSEN system is designed to operate in a fully autonomous mode and allows detecting and classifying suspicious (target) seismic acoustic activities in the area along protected objects.

Perimeter control, intrusion detection, location

Core RELSEN functionality is based on the modern methods of reflectometric interferential spectroscopy and high vibrosensitivity of a coherent flow of infrared energy that is injected into a dedicated fiber optic cable through a conventional infrared laser with a wavelength of 1550.116 nm.

The RELSEN system is designed to operate in a fully autonomous mode and allows detecting and classifying suspicious (target) seismic acoustic activities in the area along protected objects. The detection accuracy of the mechanical activity is ~ 5-10 m

Perimeter control

Value examples of sound pressure exerted on the ground
as a result of vibro-acoustic pulse effects are:

Walking or running man: 10-30 dB;
Petrol car engine: 10-40 dB;
Diesel engine (truck): 40-70 dB;
Passenger traffic vehicle at a speed of 30 km / h: 60-80 dB;
Truck at a speed of 30 km/h: 70-90 dB;
Hand digging: 30-50 dB;
Tracked vehicles: 100-120 dB;
Mechanical digging : 80 - 120 dB.

Value examples of sound pressure

№	Type	Feature	Specifications
1	Сonsumer properties	Upper bounds for probability of the Type I & Type II errors	5%
2		The minimum of the targeted seismoacoustic set cardinality	10
4		FOS maximum length without Remote Optical Pumped Amplifier (ROPA)	40 km
5		Maximum length of a FOS module with one ROPA unit	60 km
6		Maximum length of the FOS with two ROPA units	75 km
7		Seismoacoustic event detection resolution	5 m
8	Technical properties	Laser class	3B
9		Wave length	1550 nm
10		Type of optical fiber used as a FOS	G.652
11		Information extraction principle	Comprehensive analysis of the Rayleigh speckles
12		Operating temperature	+5 - +55 ° C
13		Storage temperature	0 - +70 ° C.
14		Relative humidity	10 - 80%
15		Working height above sea level	<4000 m
16		Noise level	<45 dB
17		Power 1	220 V, 50 Hz
18		Power 2	+48
19		Power consumption	90 W
20		Weight	Up to 15 kg

Perimeter control, intrusion detection, location

RELSEN fundamental design features:

Characteristics of the reflected scattered Rayleigh signal as a function of time (not the time-averaged value) are matched at the registration data array;
Reflected signals contain information sufficient for their classification and therefor enable to identify specific SEV type;
Pulses have a length of ~ 50-200 ns, with an interval of ~ 50-300 ms;
Pulse is filtered by fiber Bragg gratings, which remove amplified spontaneous (spurious) radiation;
The energy of each pulse is 0.2 micro joule;
Scattered radiation is amplified and filtered to remove any radiation other than one with a central wavelength of 1550.116 nm;
Photodiode Gallium Arsenide (GaAs) is connected to an optical fiber and used as a detector to record the amplified radiation;
Two pulses are compared at different times in order to determine the difference between reflected signals. This difference indicates a change of physical configurations of fibers (degree of deformation) that occurred on a particular way at the FOS location, due to exposure to acoustic longitudinal microstrains;
Difference between pulses is measured using robust correlation methods, including those based on the wavelet transformation; analysis of similarity degree of pulses is used to estimate amount of change in signal parameters caused by the SEV influence.