diff --git a/frequency.py b/frequency.py
index 2dba38c8..349d545e 100644
--- a/frequency.py
+++ b/frequency.py
@@ -370,6 +370,17 @@ if (doppler_mode == 'off'):
         
 if (doppler_mode == 'sim'):
   print("Sim mode")
+	
+  if (mode == 'e'):
+    tx_doppler_start_hz = txrf * 1e6
+  else:
+    tx_doppler_start_hz = txf * 1e6
+  tx_doppler_shift_hz = 0
+  print(f"Tx center frequency: {tx_doppler_start_hz}")
+  rx_doppler_start_hz = rxf * 1e6
+  rx_doppler_shift_hz = 0
+  print(f"Rx center frequency: {rx_doppler_start_hz}")
+	
   TARGET_PASS = 85           # Maximum elevation profile
   doppler_table = iss_doppler_passes[TARGET_PASS]
   print(f"Pass Max Elevation: {TARGET_PASS}°")