diff --git a/sbapp/sideband/geo.py b/sbapp/sideband/geo.py
index 0932607..c4ca0d5 100644
--- a/sbapp/sideband/geo.py
+++ b/sbapp/sideband/geo.py
@@ -223,42 +223,78 @@ def orthodromic_distance(c1, c2, ellipsoid=True):
     else:
         return spherical_distance(c1, c2)
 
-# def tests():
-#     import RNS
-#     import numpy as np
-#     from geographiclib.geodesic import Geodesic
-#     geod = Geodesic.WGS84
-#     coords = [
-#         [(51.2308, 4.38703, 0.0), (47.699437, 9.268651, 0.0)],
-#         [(51.230800, 4.38703, 0.0), (51.230801, 4.38703, 0.0)],
-#         [(35.3524, 135.0302, 100), (35.3532,135.0305, 500)],
-#         [(57.758793, 22.605194, 0.0), (43.048838, -9.241343, 0.0)],
-#         [(0.0, 0.0, 0.0), (0.0, 0.0, 0.0)],
-#         [(-90.0, 0.0, 0.0), (90.0, 0.0, 0.0)],
-#         [(-90.0, 0.0, 0.0), (78.0, 0.0, 0.0)],
-#         [(0.0, 0.0, 0.0), (0.5, 179.5, 0.0)],
-#         [(0.7, 0.0, 0.0), (0.0, -180.0, 0.0)],
-#     ]
-#     for cs in coords:
-#         c1 = cs[0]; c2 = cs[1]
-#         print("Testing: "+str(c1)+"  ->  "+str(c2))
-#         us = time.time()
-#         ld = c1+c2; g = geod.Inverse(c1[0], c1[1], c2[0], c2[1])
-#         print("Lib computed in "+str(round((time.time()-us)*1e6, 3))+"us")
-#         us = time.time()        
-#         eld = orthodromic_distance(c1,c2,ellipsoid=True)
-#         if eld:
-#             print("Own computed in "+str(round((time.time()-us)*1e6, 3))+"us")
-#         else:
-#             print("Own timed out in "+str(round((time.time()-us)*1e6, 3))+"us")
-#         ed_own = euclidian_distance(c1,c2,ellipsoid=True)
-#         sd_own = orthodromic_distance(c1,c2,ellipsoid=False)
-#         aa = azalt(c1,c2,ellipsoid=True)
-#         fac = 1
-#         if eld: print("LibDiff   = "+RNS.prettydistance(g['s12']-eld)+f"  {fac*g['s12']-fac*eld}")
-#         print("Spherical = "+RNS.prettydistance(sd_own)+f" {fac*sd_own}")
-#         # print("EllipLib  = "+RNS.prettydistance(g['s12'])+f" {fac*g['s12']}")
-#         if eld: print("Ellipsoid = "+RNS.prettydistance(eld)+f" {fac*eld}")
-#         print("Euclidian = "+RNS.prettydistance(ed_own)+f" {fac*ed_own}")
-#         print("AzAlt     = "+f" {aa[0]} / {aa[1]}")
-#         print("")
+def distance_to_horizon(c, ellipsoid=False):
+    if ellipsoid:
+        raise NotImplementedError("Distance to horizon on the ellipsoid is not yet implemented")
+    else:
+        # TODO: This is a only barely functional simplification.
+        # Need to calculate the geodesic distance to the horizon
+        # instead.
+        if len(c) >= 3:
+            r = mean_earth_radius
+            h = c[2]
+            return sqrt(pow((h+r),2) - r*r)
+        else:
+            return None
+
+def angle_to_horizon(c, ellipsoid=False):
+    if ellipsoid:
+        raise NotImplementedError("Angle to horizon on the ellipsoid is not yet implemented")
+    else:
+        r = mean_earth_radius
+        h = c[2]
+        return degrees(-acos(r/(r+h)))
+
+def radio_horizon(c1, c2, ellipsoid=False):
+    # dr = 4.12*(√h1 + √h2)
+    if ellipsoid:
+        raise NotImplementedError("Radio horizon on the ellipsoid is not yet implemented")
+    else:
+        h1 = c1[2]
+        h2 = c2[2]
+        ed = euclidian_distance(c1,c2)
+        rh1 = 1e3*4.12*(sqrt(h1))
+        rh2 = 1e3*4.12*(sqrt(h2))
+        rhc = 1e3*4.12*(sqrt(h1) + sqrt(h2))
+        return (rh1, rh2, rhc, rhc > ed)
+
+def tests():
+    import RNS
+    import numpy as np
+    from geographiclib.geodesic import Geodesic
+    geod = Geodesic.WGS84
+    coords = [
+        [(51.2308, 4.38703, 0.0), (47.699437, 9.268651, 0.0)],
+        [(51.2308, 4.38703, 0.0), (47.699437, 9.268651, 30.0*1e3)],
+        # [(51.230800, 4.38703, 0.0), (51.230801, 4.38703, 0.0)],
+        # [(35.3524, 135.0302, 100), (35.3532,135.0305, 500)],
+        # [(57.758793, 22.605194, 0.0), (43.048838, -9.241343, 0.0)],
+        # [(0.0, 0.0, 0.0), (0.0, 0.0, 0.0)],
+        # [(-90.0, 0.0, 0.0), (90.0, 0.0, 0.0)],
+        # [(-90.0, 0.0, 0.0), (78.0, 0.0, 0.0)],
+        # [(0.0, 0.0, 0.0), (0.5, 179.5, 0.0)],
+        # [(0.7, 0.0, 0.0), (0.0, -180.0, 0.0)],
+    ]
+    for cs in coords:
+        c1 = cs[0]; c2 = cs[1]
+        print("Testing: "+str(c1)+"  ->  "+str(c2))
+        us = time.time()
+        ld = c1+c2; g = geod.Inverse(c1[0], c1[1], c2[0], c2[1])
+        print("Lib computed in "+str(round((time.time()-us)*1e6, 3))+"us")
+        us = time.time()        
+        eld = orthodromic_distance(c1,c2,ellipsoid=True)
+        if eld:
+            print("Own computed in "+str(round((time.time()-us)*1e6, 3))+"us")
+        else:
+            print("Own timed out in "+str(round((time.time()-us)*1e6, 3))+"us")
+        ed_own = euclidian_distance(c1,c2,ellipsoid=True)
+        sd_own = orthodromic_distance(c1,c2,ellipsoid=False)
+        aa = azalt(c1,c2,ellipsoid=True)
+        fac = 1
+        if eld: print("LibDiff   = "+RNS.prettydistance(g['s12']-eld)+f"  {fac*g['s12']-fac*eld}")
+        print("Spherical = "+RNS.prettydistance(sd_own)+f" {fac*sd_own}")
+        # print("EllipLib  = "+RNS.prettydistance(g['s12'])+f" {fac*g['s12']}")
+        if eld: print("Ellipsoid = "+RNS.prettydistance(eld)+f" {fac*eld}")
+        print("Euclidian = "+RNS.prettydistance(ed_own)+f" {fac*ed_own}")
+        print("AzAlt     = "+f" {aa[0]} / {aa[1]}")
+        print("")