S-1 SLC to GRD, do not retreive the GRD product

Hi !

I’m new on the SNAP toolbox but also on SAR technology, so excuse me in advance if I’m not clear or precise .
Briefly for the context, I need to integrate some simulated SAR vignettes inside real SAR imagery and for that, I need complex data format (real + imaginary).
Since GRDH product does not provide this format, I have to work directly on SLC product as input, but my objective is to retreive the exact GRD product from SLC thanks to SNAP toolbox.
To resume, I need GRD format as output, but I can only work on SLC complex format as input, so my pipeline should be :
SLC Product → Integrate simulated SAR vignettes → Process to obtained GRD product exactly similar to the one we can obtain on Copernicus Open Access Hub in parallel of the SLC product.

As a first step, before the integration of simulated SAR vignettes, I try to find the correct pipeline of processing operations to go from the SLC to the GRDH product (such as the one we can download).
Unfortunately, I’m actually unable to acheive such processing.

I try the Sentinel-1 TOPS / S-1 SLC to GRD operation, but the output is very different from the GRDH one. Two main problems : the resolution is not the same (GRD product is like 26000 x 16000 pixels but my output is 14000 x 13000 pixels), the other problem is that the three sub-Swaths does not align after the TOPS Deburst operation.

Is my objective feasible or do I need to find another solution ?

Thanks in advance and have a nice day !

Théo V.

Hi !

Another issue that I have is that I cannot apply Thermal Noise Removal operation if I apply the TOPS Deburst operation before (get an error that say that the Thermal Noise Removal made a division by 0)

From my research on the User guides of Sentinel-1, I maybe found an answer for my problem and I think I will not be able to retreive the GRD product from the SLC one…

First, it seems that the GRD and SLC product come from the same product where differents operations are apply to output the two product :

Level-1 Post-Processing Algorithms - Sentinel-1 SAR Technical Guide - Sentinel Online - Sentinel Online (esa.int)

Second is that the user guide says that, on the GRD product, multilook operation is performed on each burst individually but I cannot find how to perform such operation on the SNAP toolbox (multilook seems to be applied only on the full image) :

User Guides - Sentinel-1 SAR - Level-1 - Sentinel Online - Sentinel Online (copernicus.eu)

If a specialist can confirm my doubt it will be perfect.

Thanks in advance,

Théo V.

The product you are trying to generate will be “GRD-like” and not identical to actual GRD products. Have you considered downloading both SLC and GRD?

Hi !

Thanks for the answer !
Yes, I consider downloading both SLC and GRD products, my problem is that I need to incoporate simulated data inside GRD product. The problem is that my simulated SAR data are in complex format and the proper way for incrustation would have been to incorporate it inside the complex format of the SLC product and then apply the operations pipeline to retreive exactly the GRD product.

But, as you tell me, I will not be able to generate exactly the GRD product, so I think I’ll have to find a solution to work directly and only on the GRD product.

Thanks again for the answer and have a nice day !

Théo V.