Algorithm

Based on description by Raffaele Nutricato who provided this code: In the code, look for:

//____RaffaeleNutricato START MODIFICATION SECTION 1

As I explained in the previous e-mail range oversampling is obtained
as convolution of the zero filled signal with a truncated sinc.  The
loading of the image is performed line by line and consequently the
oversampling is performed line by line too.
  
In particular given an input signal:
   Input signal: xxxx
   and an oversampling ratio of let's say 3
   I first generate a zero-filled copy of the input signal:
   zero-filled Input signal: x00x00x00x
   then I convolve the zero-filled Input signal with the interpolation
   kernel obtaining the output signal:
   Output signal: x++x++x++x++
   where +'s are the new samples.

Bert Kampes implemented the azimuth oversampling. In azimuth a 6 point raised cosine kernel is used. The kernel is normalized. I also normalized the range kernel (typically 16 point sinc).