diff --git a/charon_vna/gui.py b/charon_vna/gui.py
index fc2668a..2910d7d 100644
--- a/charon_vna/gui.py
+++ b/charon_vna/gui.py
@@ -36,7 +36,7 @@ class MainWindow(QMainWindow):
 
     plots: List[PlotWidget]
 
-    def __init__(self, uri: str | None = None):
+    def __init__(self, ip: str | None = None):
         super().__init__()
 
         self.config_path = DEFAULT_CONFIG
@@ -47,8 +47,8 @@ class MainWindow(QMainWindow):
         vna_kwargs = dict(
             frequency=self._frequency,
         )
-        if uri is not None:
-            vna_kwargs["uri"] = uri
+        if ip is not None:
+            vna_kwargs["ip"] = ip
         self.vna = Charon(**vna_kwargs)
 
         mpl.use("QtAgg")
@@ -206,12 +206,17 @@ def main() -> None:
     except Exception as e:
         if e.args[0] == "No device found":
             dialog = QInputDialog()
-            text, ok = dialog.getText(None, "Pluto IP Address", "IP Address", QLineEdit.Normal, "")
+            text, ok = dialog.getText(
+                None,
+                "Pluto IP Address",
+                "Enter Pluto IP Address",
+                QLineEdit.Normal,
+                "192.168.2.1",
+            )
             match = re.match(r"(\d{1,3}\.){3}\d{1,3}", text)
             if not match:
                 raise ValueError(f"Invalid IP address: {text}")
-            uri = f"ip:{text}"
-            window = MainWindow(uri=uri)
+            window = MainWindow(ip=text)
         else:
             raise e
 
diff --git a/charon_vna/vna.py b/charon_vna/vna.py
index 8cf49c8..8ecf4a9 100644
--- a/charon_vna/vna.py
+++ b/charon_vna/vna.py
@@ -36,9 +36,11 @@ def generate_tone(f: float, fs: float, N: int = 1024, scale: int = 2**14):
 class Charon:
     FREQUENCY_OFFSET = 1e6
 
+    calibration: rf.calibration.Calibration | None = None
+
     def __init__(
         self,
-        uri: str = "ip:192.168.2.1",
+        ip: str = "192.168.2.1",
         frequency: npt.ArrayLike = np.linspace(1e9, 2e9, 3),
         ports: Tuple[int] = (1,),
     ):
@@ -46,7 +48,7 @@ class Charon:
         self.frequency = frequency
 
         # everything RF
-        self.sdr = adi.ad9361(uri=uri)
+        self.sdr = adi.ad9361(uri=f"ip:{ip}")
         for attr, expected in [
             ("adi,2rx-2tx-mode-enable", True),
             # ("adi,gpo-manual-mode-enable", True),