Merge pull request #39 from amhirsch/DF-17Additions

Additional Information Extracted from TC-19/BDS0,9 Messages

pyModeS/decoder/adsb.py

@@ -143,24 +143,36 @@ def altitude(msg):
         return None
 
 
-def velocity(msg):
+def velocity(msg, rtn_sources=False):
     """Calculate the speed, heading, and vertical rate
     (handles both airborne or surface message)
 
     Args:
         msg (string): 28 bytes hexadecimal message string
+        rtn_source (boolean): If the function will return
+            the sources for direction of travel and vertical
+            rate. This will change the return value from a four
+            element array to a six element array.
 
     Returns:
-        (int, float, int, string): speed (kt), ground track or heading (degree),
+        (int, float, int, string, string, string): speed (kt),
-            rate of climb/descend (ft/min), and speed type
+            ground track or heading (degree),
-            ('GS' for ground speed, 'AS' for airspeed)
+            rate of climb/descent (ft/min), speed type
+            ('GS' for ground speed, 'AS' for airspeed),
+            direction source ('true_north' for ground track / true north
+            as refrence, 'mag_north' for magnetic north as reference),
+            rate of climb/descent source ('Baro' for barometer, 'GNSS'
+            for GNSS constellation).
+            
+            In the case of surface messages, None will be put in place
+            for vertical rate and its respective sources.
     """
 
     if 5 <= typecode(msg) <= 8:
-        return surface_velocity(msg)
+        return surface_velocity(msg, rtn_sources)
 
     elif typecode(msg) == 19:
-        return airborne_velocity(msg)
+        return airborne_velocity(msg, rtn_sources)
 
     else:
         raise RuntimeError("incorrect or inconsistant message types, expecting 4<TC<9 or TC=19")

pyModeS/decoder/bds/bds06.py

@@ -141,15 +141,21 @@ def surface_position_with_ref(msg, lat_ref, lon_ref):
     return round(lat, 5), round(lon, 5)
 
 
-def surface_velocity(msg):
+def surface_velocity(msg, rtn_sources=False):
     """Decode surface velocity from from a surface position message
     Args:
         msg (string): 28 bytes hexadecimal message string
+        rtn_source (boolean): If the function will return
+            the sources for direction of travel and vertical
+            rate. This will change the return value from a four
+            element array to a six element array.
 
     Returns:
-        (int, float, int, string): speed (kt), ground track (degree),
+        (int, float, int, string, string, None): speed (kt),
-            rate of climb/descend (ft/min), and speed type
+            ground track (degree), None for rate of climb/descend (ft/min),
-            ('GS' for ground speed, 'AS' for airspeed)
+            and speed type ('GS' for ground speed), direction source
+            ('true_north' for ground track / true north as reference),
+            None rate of climb/descent source.
     """
 
     if common.typecode(msg) < 5 or common.typecode(msg) > 8:
@@ -182,4 +188,7 @@ def surface_velocity(msg):
         spd = kts[i-1] + (mov-movs[i-1]) * step
         spd = round(spd, 2)
 
-    return spd, trk, 0, 'GS'
+    if rtn_sources:
+        return spd, trk, 0, 'GS', 'true_north', None
+    else:
+        return spd, trk, 0, 'GS'

pyModeS/decoder/bds/bds09.py

@@ -25,16 +25,25 @@ from pyModeS.decoder import common
 import math
 
 
-def airborne_velocity(msg):
+def airborne_velocity(msg, rtn_sources=False):
     """Calculate the speed, track (or heading), and vertical rate
 
     Args:
         msg (string): 28 bytes hexadecimal message string
+        rtn_source (boolean): If the function will return
+            the sources for direction of travel and vertical
+            rate. This will change the return value from a four
+            element array to a six element array.
 
     Returns:
-        (int, float, int, string): speed (kt), ground track or heading (degree),
+        (int, float, int, string, string, string): speed (kt),
-            rate of climb/descend (ft/min), and speed type
+            ground track or heading (degree),
-            ('GS' for ground speed, 'AS' for airspeed)
+            rate of climb/descent (ft/min), speed type
+            ('GS' for ground speed, 'AS' for airspeed),
+            direction source ('true_north' for ground track / true north
+            as refrence, 'mag_north' for magnetic north as reference),
+            rate of climb/descent source ('Baro' for barometer, 'GNSS'
+            for GNSS constellation).
     """
 
     if common.typecode(msg) != 19:
@@ -66,6 +75,7 @@ def airborne_velocity(msg):
 
         tag = 'GS'
         trk_or_hdg = round(trk, 2)
+        dir_type = 'true_north'
 
     else:
         if mb[13] == '0':
@@ -84,11 +94,18 @@ def airborne_velocity(msg):
         else:
             tag = 'TAS'
         
+        dir_type = 'mag_north'
+
+    vr_source = 'GNSS' if mb[35]=='0' else 'Baro'
     vr_sign = -1 if mb[36]=='1' else 1
     vr = common.bin2int(mb[37:46])
     rocd = None if vr==0 else int(vr_sign*(vr-1)*64)
 
-    return spd, trk_or_hdg, rocd, tag
+    if rtn_sources:
+        return spd, trk_or_hdg, rocd, tag, dir_type, vr_source
+    else:
+        return spd, trk_or_hdg, rocd, tag
+    
 
 def altitude_diff(msg):
     """Decode the differece between GNSS and barometric altitude