change the default theta_inc_sampling to 8, to account for the effect…

… of the incidence by default.

smrt/rtsolver/nadir_lrm_altimetry.py

@@ -44,7 +44,7 @@ class NadirLRMAltimetry(object):
     _broadcast_capability = {}  # "theta_inc", "polarization_inc", "theta", "phi", "polarization"}
 
     def __init__(self, waveform_model=None, oversampling=10, return_oversampled=False, skip_pfs_convolution=False,
-                 return_contributions=False, theta_inc_sampling=1, return_theta_inc_sampling=False, error_handling="exception"):
+                 return_contributions=False, theta_inc_sampling=8, return_theta_inc_sampling=False, error_handling="exception"):
         # """
 
         # """
@@ -178,7 +178,7 @@ def convolve_with_PFS_PTR_PDF(self, t_gate, backscatter, t_inc_sample):
                 # we've no PFS, we need numerical integration
                 pfs = self.PFS_numerical(t_gate)
 
-            # now take into account the ptr + pdf
+            # now take into account the PTR + PDF assuming Gaussian PTR and PDF
             if (self.sensor.pulse_sigma > 0) or (sigma_surface > 0):
                 gaussian_norm = 0.3989422804014328
                 sigma_c = np.sqrt(self.sensor.pulse_sigma**2 + (2 * sigma_surface / C_SPEED)**2)