Synthetic-aperture radar system and operating method for monitoring ground and structure displacements suitable for emergency conditions

• US 8,384,583 B2
• Filed: 06/07/2010
• Issued: 02/26/2013
• Est. Priority Date: 06/07/2010
• Status: Active Grant

• Current Assignee: Ellegi Sri
• Original Assignee: Ellegi Sri
• Inventors: Leva, Davide, Rivolta, Carlo
• Primary Examiner(s): Sotomayor, John B
• Application Number:
  US12/802,400
• Publication Number:
  US 20110298655A1
• Time in Patent Office: 995 Days
• Field of Search: 342/25.R, 342 25 A- 25 F, 342 52- 55, 342/66, 342 74- 75, 342/81, 342/156, 342159-162, 342/180, 342/188, 342/191
• US Class Current: 342/25.C
• CPC Class Codes: G01S 13/9023 combined with interferometric techniques
• CPC Class Codes: G01S 7/024 using polarisation effects in waveguides H01P1/165; for aerials H01Q, e.g. H01Q15/22, H01Q15/24, H01Q19/195
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

A synthetic-aperture radar system, and related operating method, for the monitoring of ground and structure movements, particularly suitable for emergency conditions, characterized by a ground based platform with polarimetric capabilities, that able to quickly acquire, embeddedly process and post-process data by a novel data acquisition “On the Fly” mode of operation, reducing by at least an order of magnitude the data acquisition time. The inventive system characteristics allows to achieve on-field measurement results on three-dimensional maps georeferenced to absolute coordinate systems (WGS84, Gauss-Boaga, and so on). The operating method includes the step of installing the system, the acquiring of the first measurements, the quick data processing and post-processing to provide sub-millimetric precision georeferenced bi-dimensional and three-dimensional displacement maps for the objects belonging to the monitored scenario, with an improved performance and in a measurement time compatible to that required in an emergency condition, with an higher degree of integration with other sensors and autonomously and embeddendly.

Claims

1. A synthetic aperture radar system for monitoring ground and structure movements, said system comprising at least the following mechanical and electronic components:

a ground based platform including a measurement interferometric and polarimetric sensor, an embedded power supply and connection unit, a linear positioner provided with a movable carriage, and a measuring head;

an embedded main system control unit, an embedded electromagnetic wave generator and receiver module controlled by said unit, comprising a continuous—

wave stepped—

frequency scatterometer, a motor control and managing unit, an embedded UPS module including an embedded buffer battery;

an I/O managing module, an embedded calibrated videocamera or photocamera, an embedded. GPS receiver module, an embedded display and an alphanumeric keypad, an embedded LAN module, an embedded mass storage module, an embedded GSM/GPRS/UMTS module, an embedded WLAN module, and embedded standard interfaces for assembling laser scanners and topographic instrument reflectors;

whereby all the mechanical components of said system are provided with unique reference marks and points or connections, characterized in that, to perform a measurement, said measuring head is initially driven along a linear track with a constant speed in an “

on the fly”

acquisition mode of operation; and

wherein during a constant speed movement, the system acquires data needed to process a single radar image.

2. A synthetic aperture radar system, according to claim 1, characterized in that the system achieves a synchronization of an acquired signal with an instantaneous position of the carriage by one of the following alternative modes of operation:

providing a physical embedded trigger generated by the embedded microwave generator and receiver module, providing a physical embedded trigger generated by the rotary encoder or by a linear encoder, or providing a simulation of the synchronization with a software trigger.

3. A synthetic aperture radar system, according to claim 1, characterized in that said embedded videocamera or photocamera is of a calibrated digital type allowing to reconstruct or acquire a digital terrain model of a ground and ground representing point clouds, said embedded calibrated digital videocamera or photocamera being built-in in the movable measurement head and calibrated in a way that, by driving it along the track together with the movable measurement head, different position snapshot sequences may be acquired, a set of said snapshot sequences allowing to achieve, through multifocal algorithms, point clouds or digital models indicative of a ground elevation of the analyzed area.

4. A synthetic aperture radar system, according to claim 1, characterized in that said GPS module is embedded in the measurement head and provides an absolute position of said carriage on the track, thereby retrieving, from a set of track carriage positions measured along the track, coordinates of a middle point of the track and its spatial direction according to a geographic coordinate system external and independent from the system so as to georeference the radar system results to an external WGS84 or Gauss-Boaga coordinate system.

5. A synthetic aperture radar system, according to claim 1, characterized in that said linear positioner comprises a plurality of plates and counter-plates, said counter-plates being clamped to tripods, said plates having plate surfaces including an embedded preset assembly for mounting and connecting topographic instruments, such as theodolite and total station detecting mirror elements, by connections consisting of an embedded vertical shaft including a top slot mating with a detector mirror or reflector hollow shaft, thereby allowing to georeference the radar system results into said WGS84 or Gauss-Boaga coordinate system.

6. A synthetic aperture radar system, according to claim 1, characterized in that said embedded calibrated digital videocarnera or photocamera, embedded GPS module, and embedded counter-plates measure the system spatial locations to achieve a digital elevation model of a monitored area, thereby the system provides embedded on-field results in a three-dimensional system georeferenced to said WGS84 or Gauss-Boaga coordinate system.

7. An operating method for operating a synthetic aperture radar system, according to claim 1, wherein said method comprises the steps of installing said radar system on a system base including deployable mechanical tripods;

wiring the system with two connectable cables, starting the system and setting up the measurement parameters through an embedded display and an embedded alphanumeric keypad;

acquiring data moving the measuring head at a constant speed;

processing and post-processing data on field by an embedded control and managing module and providing embedded bi-dimensional or three-dimensional maps of a monitored scenario using a measured system spatial location and a georeferenced digital model.