Parse azimuth fm rate polynomial

src/s1reader/s1_reader.py

@@ -56,7 +56,12 @@ def parse_polynomial_element(elem, poly_name):
 
     half_c = 0.5 * isce3.core.speed_of_light
     r0 = half_c * float(elem.find('t0').text)
-    coeffs = [float(x) for x in elem.find(poly_name).text.split()]
+
+    if elem.find(poly_name) is None: #some data with VERY old IPF version
+        coeffs = [float(x.text) for x in elem[2:]]
+    else: #Most of the recently processed S1 SAFE data
+        coeffs = [float(x) for x in elem.find(poly_name).text.split()]
+
     poly1d = isce3.core.Poly1d(coeffs, r0, half_c)
     return (ref_time, poly1d)