Help Content > Focusing Module

Purpose

SAR RAW data (level 0 product) acquired by Sentinel-1 must be focused to generate Single Look Complex (SLC) data, which can be used as first input for data processing in any other module.

The supported acquisition mode is:

-	Sentinel-1 IW (Interferometric Wide Swath).

Technical Note

Sentinel-1 RAW (level 0) standard format is required. The level 0 filename is formatted as S1A/B_IW_RAW_*.SAFE folder, where IW stands for Interferometric Wide swath mode.

The output product consists of Single Look Complex data.

The focusing of Sentinel-1 data requires some auxiliary file to be used:

SUPPORTED FOCUSING PRODUCTS

AUX_INS Instrument parameters

AUX_CAL Calibration parameters

SUPPORTED ORBITAL PRODUCTS

AUX_POEORB Precise Orbit Ephemerides

AUX_RESORB Restituted Orbit

Restituted orbit files (AUX_RESORB) are generated within 3 hours from the acquisition with an accuracy < 10 cm rms.

Precise orbit files (AUX_POEORB) are generated within 21 days from the acquisition with an accuracy < 5 cm rms.

Orbit files for can be downloaded with the proper SARscape tool or from https://scihub.copernicus.eu/gnss/#/home

Auxiliary file products are mandatory for the focusing of Sentinel-1 raw data. Therefore, these data need to be download in a predefined Directory, set on the Preferences panel. .

The relevant auxiliary files have to be stored in an existing folder, which has been defined as Sentinel 1 auxiliary Directory, and they cannot be insert directly in the focusing processing panel since they are automatically retrieved by the program. This Directory need to be set on the Preferences panel and has to contain 4 folders, one for each of the auxiliary product (named respectively 'AUX_INS', 'AUX_CAL', 'AUX-POEORB', 'AUX_RESORB').

Regarding the orbital auxiliary files, the program will first search in the AUX_POEORB subdirectory of the “Sentinel-1 orbit directory” for an orbit file matching the acquisition date and time of the corresponding input file. If no matching orbit file is found, the program will search also in the AUX_RESORB subdirectory, If no match is found, the program will use the orbit information provided in the input product annotations.

Technical details relevant to the data focusing process and algorithm are provided in the module overview.

PLEASE NOTE:

In case the auxiliary orbit file is not included in the orbit repository, a download query is performed to get only the missing orbit file. The downloaded file is stored in the SARscape work directory and used during the import step. Once the data is imported, the orbit file is deleted.

Input Files

Input File List

File name(s) of the original Sentinel-1 raw data, *.dat, located inside the S1A/B_IW_RAW_*.SAFE folder. These files are mandatory.

Parameters - Principal Parameters

RFI filtering

If set, RFI (Radio Frequency Interference) filtering is performed prior to the focusing step.

Azimuth time origin

Set 'South pole' or 'North pole' azimuth time origin.

Please note it is not necessary to change this setting apart the area of interest is covering one of the two poles. In that case, the opposite pole need to be set.

Reference height (m)

Set the mean height value of the area of interest

Rename the File Using Parameters

If set, only relevant information will be copied from the input name(s) to the output name(s), the full root name otherwise.

Parameters - Global

It brings to the general section of the Preferences parameters. Any modified value will be used and stored for further processing sessions.

Parameters - Other Parameters

It brings to the general section of the Preferences parameters. Any modified value will be used and stored for further processing sessions.

Output Files

Output file list

Output file name(s) of the imported data.

Each entry specifies the output path (output directory and root name) of the imported file and associated header files (.sml, .hdr). The output directory can be changed by right-clicking on the displayed root name, and selecting Change Output Directories from the dropdown menu. Click on the folder icon to browse to the output directory and then click on the green tick mark to apply the change.

These files are mandatory.

Root name of the imported file and associated header files (.sml, .hdr). Specific file suffixes are added according to the data type.

.shp

Shape file and associated header files (.sml, .hdr) containing the image perimeter in geographic co-ordinates.

.kml

ASCII file containing the image perimeter in geographic co-ordinates. Double clicking on this file will automatically position the boundaries of the scene into the Google Earth environment.

Details specific to the measurement units and naming of the output products can be found in the Data Format section.

General Functions

Exec

The processing step is executed.

Store Batch

The processing step is stored in the batch list. The Batch Browser button allows to load the batch processing list.

The window will be closed.

Help

Specific help document section.

Specific Function(s)

None.