Please have a look to the special note I have published:

https://sentinel.esa.int/documents/247904/1653442/Sentinel-1-TOPS-SLC_Deramping

Thanks for documentation.

One symbol in the document seems not defined:

pag. 6/8  formula to calculate eta_ref (tau) = eta_c(tau) - eta_c(0)  

eta_c(0) seems not well defined!?

Thanks for this documentation. Unfortunately, with my Sentinel-1 test data the deramping does not work properly.

I have the same question as Mr. Crippa above: What does eta_c(0) mean? To my understanding the azimuthFMRate and and dataDcPolynomial are functions of tau but in the sense that tau has to be reduced by the azimuth time specified for each polynomial.

Is this correct?

Is eta_c(0) now just the constant term of the polynomial or the polynomial evaluated for tau == 0?

Would be nice if there are some numerical examples!

eta_c(0) is the zero-Doppler azimuth time in the middle of the burst.

eta_c is an array that you need to compute for each range samples.

eta_c(0) is the first element of this array representing eta_c at the near range of your product