METHOD AND DEVICE FOR SEARCHING THROUGH COLLAPSED GROUND

• US 20130335257A1
• Filed: 03/08/2012
• Published: 12/19/2013
• Est. Priority Date: 03/11/2011
• Status: Active Grant

• Current Assignee: Totalforsvarets Forskningsinstitut (FOI)
• Original Assignee: Totalforsvarets Forskningsinstitut (FOI)
• Inventors: Abrahamson, Staffan
• Granted Patent: US 9,594,161 B2
• Time in Patent Office: Days
• US Class Current: 342/22
• CPC Class Codes: A63B 2220/802 Ultra-sound sensors
• CPC Class Codes: A63B 2225/50 Wireless data transmission, e.g. by radio transmitters or telemetry
• CPC Class Codes: A63B 2230/00 Measuring physiological parameters of the user
• CPC Class Codes: A63B 29/021 Means for indicating the location of accidentally buried, e.g. snow-buried, persons
• CPC Class Codes: G01S 13/56 for presence detection presence detection using near field arrangements G01V3/00, e.g. G01V3/08, G01V3/12; burglar, theft or intruder alarms with electrical actuation G08B13/22 - G08B13/26
• CPC Class Codes: G01S 13/885 for ground probing prospecting or detecting using electromagnetic waves G01V3/12

Abstract

The invention relates to a device and a method for determining whether a living person has been buried in collapsed ground. The device consists of a rod provided with a receiver unit and a signal processing unit. The receiver unit is intended to receive reflected radar signals transmitted form a radar transmitting antenna and transfer these signals to the signal processing unit. The signal processing unit which is provided with specific detection units determines whether the received signal have been Doppler shifted. By determining that the device can decide whether the Doppler shift depends on the moving chest of a breathing person buried alive.

Claims

1. Device for receiving and processing signals reflected from objects in the ground, the device is characterized in that it comprises:

a rod (1) to be inserted into the ground,

a radar transmitting and radar generating antenna provided in said rod for transmitting radar signals into the ground,

at least one signal receiving unit provided in said rod for receiving radar signals reflected from an object in the ground,

a signal processing unit connected to said signal receiving unit, said signal processing unit comprises units for main detection, said units for main detection consists of a band-pass filter, a differential detector, a comparator unit and a decision processor, said units being operated to decide whether a reflected signal has been Doppler shifted and thereby decide whether an object in the ground is moving.

2. Device according to claim 1, characterized in that said rod (1) in its length direction is divided into several sections (2), each of said sections being equipped with a signal receiving unit provided on said rod for receiving signals reflected from objects in the ground, said signal receiving units being electronically connected to a signal processing unit, said signal processing unit comprising units for main detection, said units for main detection consists of a band-pass filter, a differential detector, a comparator unit and a decision processor, said sections, corresponding to different length segments of the rod provide an indication of the ground depth where a moving object has been detected.

3. Device according to claim 2, characterized in that said sections (2) are divided into sectors (3) provided peripherally around the rod, each of said sectors comprises their own signal receiving unit and are electronically connected to a signal processing unit, whereby signals received by a specific receiving unit are processed to determine whether an reflected radar signal has been Doppler shifted and thereby determine whether an object in the ground is moving, each of said sectors provide information about the angular position relative the rod where the Doppler shift were detected.

4. Method for determining the position of a moving buried object by using a radar transmitting unit and a device according to claim 1 for receiving radar signals reflected form an object in the ground, the method is characterized by the steps of:

a) letting a radar transmitting unit provided in the rod generate a radar signal that is transmitted into the ground,

b) inserting the rod into the ground,

c) using the receiver provided in said rod to receive radar signals reflected from an object in the ground and transfer these signals to the signal processing unit,

d) letting the band-pass filter sort out those radar signals whose frequency components does not correspond to Doppler shifted frequencies, transferring the remaining radar signals to a differential detector, e) letting the differential detector determine the derivative of the amplitude of the received radar signal and determine an absolute value of this derivative,

f) letting a decision processor compare the absolute value of the derivative with a threshold value corresponding to the background noise in the ground, if said absolute value of the derivative is larger than the threshold value a detection of a Doppler shift is considered to have happened, if a Doppler shift exists letting a presentation unit present the result.

5. Method according to claim 4, characterized in that all steps are repeated in a number of different positions in the ground and that the data from the measurements on the different positions are compared to determine the position of the moving object by means of triangulation.