TABLE 3 
CORRELATION COEFICIENT RANGES 
  
  
  
  
  
classes HH-VVc HH-VVp HV-VHp 
sugar beet "0.66 .56-.61 .38-.61 
stubble «50—.71 «12—.60 ‚04-.18 
wheat «27—.34 .18-.28 ‚07-.31 
potato ‚51-.54 2437.57 «70—.78 
  
Lower stability is noticeable for the cases when 
the correlation coefficient is low. For example, 
the anomalous value  -118 degrees for HH-VVp 
(stubble) occurs when the correlation is .12. The 
greater variability of wheat coincides with low 
correlations. 
Special note has to be given to HV-VHp: for stubble 
and wheat classes the correlation is low, in 
contradiction to that is expected by the theory. 
This result can be explained due to cross-talk and 
the influence of noise in low backscatter regions, 
as discussed in [5]. HV-VH phases differences for C 
band were “103 degrees, which goes to zero when 
calibration is done. No discrimination was observed 
when using HV-VH. All other remaining correlations 
were zero and no other phase information was 
observed. 
4. CONCLUSIONS 
The overall conclusion is that the phase 
information can be observed, that is, it is 
possible to have well peaked phase differences but 
only HH-VV phases can be discriminatory, and 
independent from amplitude information. Amplitude 
information seems to have influence on the level of 
noise included in the phases statistics and so in 
the phase information quality. These results 
reinforce the importance of working with complex 
data, and suggest that, even without calibration, 
phases differences can be potentially used for 
classification. 
REFERENCES 
[1] F T Ulabi and C Elachi (eds) Radar polarimetry 
for geoscience applications, Artech House Inc., 
1990. 
[2] L V Dutra, .S Quegan, R CG Caves, "The 
information content onf Maestro-1 images" In 1991 
INTERN. GEOSCIENCE AND REM. SENSING SYMPOSIUM 
(IGARSS'91),  Espoo, Finland, June 3-6, 1991. 
Proceedings. Helsinki University of Technology, 
vol2, pp 345-348. 
[3] J A Kong (ed.) Polarimetric remote sensing. 
Elsevier Science Publishing Co., 1990. 
[4] W H Press, B P Flanery, S A Teukolsky, W T 
Vetterling. Numerical Recipes in C. Cambridge 
University Press, Cambridge, 1988. 
[5] S Quegan, L V Dutra, I Rhodes. " Does phase 
carry information in quadpolarized SAR data?". In: 
1992 INTERN. GEOSCIENCE AND REM. SENSING SYMPOSIUM, 
Houston, Texas, May 26-29, 1992. 
610