Calibration Constant Validation

Hello,

I have got calibration factor for Sentenal image… How can I validate it??

In the SNAP tools meta data file I see the factor to be 9999 dB. What does this mean…

Thank you
Regards

the calibration constant should actually be given in the metadata. Did you open the S1 product with the import function?

Hello, ABraun…

I have done that… This is what I am getting

Does this mean the calibration factor is 9999dB???

you are right, sorry. This obviously only applies for TerraSAR-X. Maybe the sentinel calibration configuration is stored at another place in the metadata.

Hello, The location of the Sentinel-1 calibration constant can be found in the product specfication document (https://sentinel.esa.int/documents/247904/1877131/Sentinel-1-Product-Specification) and is shown below:

For S1-A the absolute calibration factor has a value of 1.0 (or 0dB) while for S1-N it is 1.393 (or 1.44dB).

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Hello,
I appreciate your effort in helping me understand this issue…

"For S1-A the absolute calibration factor has a value of 1.0 (or 0dB) while for S1-N it is 1.393 (or 1.44dB)."

Is this applicable to GRD images.
Calibration factor = 0dB
Does this mean there is no need of calibration for the acquired image.

Hi,

The same calibration constants apply to all Level 1 product types (GRD & SLC). If you wish to convert the product digital numbers (DNs) to radar cross-section yourself then I suggest you read the ESA document ‘Radiometric calibration of S1 level 1 products generated by the S-1 IPF’ which is available at https://sentinel.esa.int/documents/247904/685163/S1-Radiometric-Calibration-V1.0.pdf. Basically the product annotation includes a conversion from DN to radar cross-section. The document explains this and gives an example.

Thank you so much…