# Sentinel1 some parameters

Hello,

I have some questions while I was using Sentinel-1 IW SLC images.

First, where can I get velocity information (satellite, ground(footprint) and effective)?
In some Sentinel documents, there is a calculation “Ve=sqrt(Vs*Vg)”, but I have no idea what each values are.

Also, chirp information (range chip length, chirp bandwidth, chirp sign, etc) could not be found except that the chirp source is ‘nominal’.
I want to know exact values about those for each images.

Third, in some documents, I could find followed one,

Then, which one is “effective” azimuth dimension between 3.4 and 3,9?

Last, as I know the satellite flies al 693km altitude, but I think the exact height would be different every scene. Is there any parameters about it?

Please let me know where I can find each information for each images.

I’m writing some questions about the Sentinel1 images.
To sum it up,

• Sensor and satellite velocity information (satellite, ground(footprint), effective)
• Image chirp information (range chip length, chirp bandwidth, chirp sign, etc)
• Effective antenna azimuth dimension
• Exact satellite altitude

Even if this is little different from SNAP, I would appreciate it if you let me know where I can find these.

Thank you

For information about products and modes you can consult:

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

Satellite distance from the centre of the Earth and it’s velocity are very well known, this info is in the orbit files, see:

https://sentinel.esa.int/documents/247904/351187/GMES_Sentinels_POD_Service_File_Format_Specification

Since the Earth is not exactly a sphere, has some topgraphy (DEM) and does not have a uniform gravity field, the altitude over ground varies and needs to be calculated. When calculating the velocity of the beam on the ground the rotation of the Earth needs to be taken into account.

Regarding spacecraft dimensions I’m guessing envelope dimensions dictate how much space it requires inside the launcher fairing in launch configuration. This does not have anything to do with the azimuth-dimension when SAR imaging is discussed.

I hope this helps!

Thanks a lot! They would be helpful.

Hi, In addition to the reply above, information on the antenna including the physical size can be found at https://sentinel.esa.int/web/sentinel/technical-guides/sentinel-1-sar/sar-instrument.

Also the following documents may be of interest:

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