<< Click to Display Table of Contents >> Navigation:  Help Content > General Tools > Data and Quality Analysis > General Tools - Data and Quality Analysis - Doppler Estimation

Purpose

 

The Doppler can be estimated directly from RAW and from SLC data, as phase difference (complex conjugate product) along azimuth direction, from the raster image itself.

The goal of this tool is to update the .sml header file of the input data, with the new Doppler polynomial (in SARscape standard format). The technique consist not strictly in a phase difference along azimuth, but it perform also an average of this phase difference in range direction due to the estimation noisiness.  

The resulting Doppler value is centered to the first PRF replica in the image center. An unwrapping is performed along azimuth to retrieve the entire Doppler amount.

In output are provided two raster file as assessment for the Doppler estimation tool:

-the measured Doppler (in Hz)

-the fitted Doppler (in Hz) as it will be used by SARscape.

 

The SARscape Doppler polynomial use the following convention.

A user defined number of slant range depending polynomial are generated (Doppler AZ Poly Number).

Each polynomial is defined by an azimuth time and depend from the slant range time distance in the following way:

Doppler (Hz) = K1 + K2(T-T0) + K3(T-T0)2+ K4(T-T0)3

where T is the pixel slant range time distance and T0 is the common slant range time reference for all the polynomial. kx are the estimated coefficient (the number is defined by Doppler RG Poly Degree).

The azimuth dependency (Doppler AZ Poly Degree) is implemented by a linear interpolation of the closer polynomial to the image line considered.

 

Technical Note

 

The file generated are the followings:

•out_dopp:                measured Doppler (in Hz)

•out_dopp_ext:                fitted Doppler (in Hz)

 

 

 

Input Files

 

Output file list

Output file root name(s). The number of output files must be equal to the number of input files. This file list is mandatory.

 

Parameters - Principal Parameters

 

Doppler RG Poly Degree

Doppler RG Poly Degree

 

Doppler AZ Poly Degree

Doppler AZ Poly Degree.

 

Doppler AZ Poly Number

Doppler polynomial number in azimuth. If the Azimuth poly degree is 1 (just a constant), a unique polynomial is needed.

 

Parameters - Global

 

It brings to the general section of the Preferences parameters. Any modified value will be used and stored for further processing sessions.

 

Parameters - Other Parameters

 

It brings to the general section of the Preferences parameters. Any modified value will be used and stored for further processing sessions.

 

Output Files

 

.sml

The input .sml file will be updated.

 

out_dopp

Measured doppler (in Hz) .

 

out_dopp_ext

Fitted doppler (in Hz).

 

 

 

General Functions

 

Exec

The processing step is executed.

 

Store Batch        

The processing step is stored in the batch list. The Batch Browser button allows to load the batch processing list.

 

Close        

The window will be closed.

 

Help

Specific help document section.

 

 

Specific Function(s)

 

None.

 

See Also

 

Task, SARscapeBatch object, SARscapeBatch script example

 

References

 

None.