added formulas

api/app/services/link.py

@@ -47,6 +47,9 @@ def link_budget(request: LinkBudgetRequest, db: Session | None = None) -> LinkBu
     )
     atmospheric_db = atmospheric_loss_between(tx, rx, freq_hz)
 
+    active_diffraction_db = diffraction_db
+    active_atmospheric_db = atmospheric_db
+
     if request.model == "manual":
         propagation_db = 0.0
     elif request.model == "itm":
@@ -70,6 +73,7 @@ def link_budget(request: LinkBudgetRequest, db: Session | None = None) -> LinkBu
                 request.frequency_mhz,
             ).fspl_db
         )
+        active_diffraction_db = propagation_db
     elif request.model == "p452":
         propagation_db = (
             p452_loss(
@@ -91,6 +95,8 @@ def link_budget(request: LinkBudgetRequest, db: Session | None = None) -> LinkBu
                 request.frequency_mhz,
             ).fspl_db
         )
+        active_diffraction_db = propagation_db
+        active_atmospheric_db = 0.0
     else:
         raise NotImplementedError(f"{request.model} link model is not supported")
 
@@ -102,9 +108,9 @@ def link_budget(request: LinkBudgetRequest, db: Session | None = None) -> LinkBu
         rx_gain_dbi=request.rx.gain_dbi,
         sensitivity_dbm=request.rx.sensitivity_dbm,
         frequency_mhz=request.frequency_mhz,
-        diffraction_db=diffraction_db + propagation_db,
+        diffraction_db=active_diffraction_db,
         vegetation_db=vegetation_db,
-        atmospheric_db=atmospheric_db,
+        atmospheric_db=active_atmospheric_db,
         fresnel_clear=los_result.los_clear,
     )
     geometric_obstructions = [