sentinel-1 SLC product

Microwave Toolbox
1

Hello Dear All,
I am using Sentinel 1 Level 1 Product downloaded from ESA and I have one question?
In Level 1 Product Annotation, “startTime” and “stopTime” is defined, but why the first ‘‘fineDceAzimuthStartTime’’ is before the “startTime” , the last ‘‘fineDceAzimuthStopTime’’ is later the “startTime” ？ Could you please help me?
Best regards
Martin

2

This document explains the annotations:

https://sentinel.esa.int/documents/247904/1877131/Sentinel-1-Product-Specification

3

Thanks for your reply. I have downloaded this document before, in which the meaning of each field has been introduced, but did not say why.

4

According to the document:

fineDceAzimuthStartTime = First zero Doppler azimuth time of the block of signal data used for the fine DC estimates [UTC].

It means that DC (Doppler Centroid) estimates are done in consecutive blocks and that is the startTime of the DC estimation block that contains the image startTime.

5

Oh, I see, thanks for your reply.