Ground-based, multi-bistatic interferometric radar system for measuring 2D and 3D deformations

A method for determining a displacement vector field of a deformable scenario, comprising the steps of:

• prearranging a main radar device having a transmission unit and a main radar device reception unit for receiving from a first field of sight;
• prearranging at least one passive radar device having a passive radar device reception unit for receiving from a second field of sight, at a predetermined distance from said main radar device, said main radar device and said or each passive radar device having respective oscillators associated to said main radar device reception unit and to said transmission unit, or to said passive radar device reception unit, respectively;
• said main radar device and said or each passive radar device arranged in such a way that said scenario is included in a region common to said first field of sight and to said second field of sight;
• wherein the steps of prearranging said main radar device and said or each passive radar device comprise steps of measuring respective positions and respective orientations in a global reference system, synchronizing said or each passive radar device with said main radar device, comprising:
• a step of aligning a time reference of said main radar device with a time reference of said or each passive radar device;
• a step of aligning an oscillation frequency reference of said oscillators of said main radar device and of said or each passive radar device;
• interferometrically determining at least one first displacement map and a second displacement map of said scenario between a previous time and a subsequent time in said main radar device and in said or each passive radar device, respectively, said at least one first and one second displacement maps expressed in said global reference system, said at least one first and one second displacement maps having each a plurality of pixels each associated to a respective domain of said scenario, said first displacement map comprising, for each own pixel, a respective first displacement component along a first line of sight of said main radar device with respect to said domain, said second displacement map comprising, for each own pixel, a respective second displacement component along the bisector of an angle formed by said first line of sight and by a second line of sight of said or each passive radar device with respect to said domain;
• combining said first displacement map and said second displacement map, wherein at each pixel said respective first displacement component and said respective second displacement component are combined to obtain a displacement vector of said respective domain between said previous time and said subsequent time, in order to form said displacement vector field,
• wherein said step of interferometrically determining said first and said second displacement map comprises steps of:
• firstly and secondly scanning said scenario, said firstly and said secondly scanning performed starting from said previous time and from said subsequent time, respectively, each of said firstly and secondly scanning comprising a plurality of consecutive steps, each step comprising the steps of:
• transmitting radar transmission signals by said main radar device, wherein, in each of said consecutive steps, said radar transmission signal is emitted by a transmission element of said transmission unit of said main radar device having a different transmission and/or orientation position with respect to another of said consecutive steps;
• receiving, by said main radar device, synchronously and coherently to said step of transmitting, and acquiring first data in the form of a backscattered radar signal from said scenario;
• receiving, by said or each passive radar device, synchronously and coherently to said step of transmitting, and acquiring second data in the form of a scattered radar signal coming from said scenario;
• processing said first data and said second data in said main radar device and in said or each passive radar device, respectively, obtaining a first and a second previous image of said scenario, pertaining to said previous time, and a first and a second subsequent image of said scenario, pertaining to said subsequent time;
• comparing said first subsequent image with said first previous image, and said second subsequent image with said second previous image, obtaining a first displacement map and a second displacement map, respectively, of said scenario, said first and second displacement maps expressed in said global reference system, said first and second displacement maps having each a plurality of pixels each associated to a respective domain of said scenario.