Internal

BISTATIC Work plan

 The project integrates into the ESA‐Romania priorities, addressing an area of study and research that includes sensors and measuring instruments, and having as end‐product and results an experimental platform (ground‐based fixed receiver bistatic SAR system) for the demonstration of bistatic SAR measuring techniques with applications in support of the ground‐segment.

 

The project contributes to the development of cutting edge technology in support of GMES services that address emergency response and security (e.g. monitoring critical infrastructure, measurements of subsidence in urban areas, area mapping). Moreover, the resulting demonstration platform is designed in preparation for the forthcoming ESA Sentinel‐1 mission envisaged to launch in 2013. The initial calibrations and synchronizations will be designed and correlated with the TerraSAR‐X mission. 

 

WP.1. Definition of system requirements, system architecture and preliminary concept  - complete

 

TSX orbit characteristics were studied, as well as orbit propagation methods based on state vectors.This will allow for the prediction of the satellite position relative to the test location during the window of opportunity.

 

A collection of Image Formation Algorithms were implemented and tested on simulated point targets in diverse configurations and with different reflectivities.

                                        

Some scientific proposals for TSX data are available for the data acquisition phase. They are to be completed in 2014 and 2015.

 

WP 2. Demonstrator System Design and Elaboration - complete

 

The hardware system is a coherent receiver with up to 4 channels. Design stage has been completed. Hardware installation is close to completion.

 

 A study on the PS density and quality has been performed for satellite data. After integration with ground-based data, the contribution of the bistatic information on PS estimation will be assessed.

 

 PSInSAR 

 

 

 

The figure shows the Persistent Scatterers identified using the spectral properties (red) and      intensity values (green). On the right we depict the Perpendicular baselines of interferometric pairs in Pursuit Monostatic mode, and the variations of pixels densities (and number) as functions of the mean/sigma ration and the coherence threshold. 

 WP 3. Data fusion  - complete

 

 One of the main objectives of the project was to build the necessary expertise and to provide hardware support for experiments that address the Sentinel-1 mission (which was not yet in orbit at project launch). To this scope both the hardware platform and software development was made to be modular, flexible and with a general architecture, so as to allow a fast and easy transition from the configuration developed for the satellite TerraSAR-X to the Sentinel-1. 

 

Satelite data
 

 

 

 

 

Due to the availability Sentinel-1 data takes last year and during this year's phase, we aimed to achieve not only experiments with the German satellite as a transmitter of opportunity, but also to go beyond the proposed objectives and measure satellite signals from the ESA Satellite as well.

 

WP 4. Validation and Demonstration - complete

 

 

Capturile bistatice efectuate la sol sunt rezumate in tabelul de mai jos. Acesta include senzorul vizat, data capturii, modul in care opera satelitul, si caracteristicile locatiei din care au fost facute capturile. Pentru orientarea sistemului a fost determinata pozitia si orientarea senzorului satelitar folosindu-se instrumentul de predictie de orbita GPREDICT [ref]. Pozitionarea sistemului de sol in coordonate geografice a fost realizata utilizandu-se un sistem GPS, iar orientarea (elevatia si azimutul) antenelor de receptie a semnalului direct si respectiv a semnalului reflectat a fost realizata folosindu-se un instrument de orientare magnetic. Din aceasta cauza in cazul primelor teste in situ efectuate, prezenta anumitor elemente metalice de pe elementul de fixare a antenelor (trepied) a condus la erori de localizare a nordului magnetic. Totusi, precizia necesara pentru orientare (pentru captarea semnalului util) a tolerat acest nivel de estimare. 

Figura 9 prezinta suprafata iluminata de senzorul Sentinel-1A si respectiv imaginea SAR bistatica formata la sol dupa focalizarea semnalului captat pe canalul 2 al receptorului BISTATIC. Figurile 10-15 prezinta caracteristicile de semnal pentru achizitia din 21/10/2015.