2-port SOLT cal

charon_vna/vna.py

@@ -1,8 +1,9 @@
 # %% imports
 import copy
+import pickle
 from enum import IntEnum, unique
 from pathlib import Path
-from typing import Any, Callable, Dict, Literal, Tuple
+from typing import Any, Callable, Dict, List, Literal, Tuple
 
 import adi
 import iio
@@ -305,7 +306,16 @@ class Charon:
 
         return np.mean(data[1] / data[0])
 
-    def capture(self, callback: Callable[int, int] | None = None):
+    def capture(
+        self,
+        callback: Callable[int, int] | None = None,
+        *,
+        measurements: List[Tuple[int, int]] = None,
+    ):
+        if measurements is None:
+            measurements = [(m, n) for n in self.ports for m in self.ports]
+        measurements = list(measurements)
+
         s = xr.DataArray(
             np.zeros(
                 [len(self.frequency), len(self.ports), len(self.ports)],
@@ -319,30 +329,31 @@ class Charon:
             ),
         )
 
-        total_count = len(s.m) * len(s.n) * len(s.frequency)
+        total_count = len(measurements) * len(s.frequency)
         count = 0
 
         for m in s.m.data:
             for n in s.n.data:
-                self.set_switches(b=m - 1, a=n - 1)
+                if (m, n) in measurements:
+                    self.set_switches(b=m - 1, a=n - 1)
 
-                for ff, freq in enumerate(s.frequency.data):
-                    if callback is not None:
-                        # report progress during sweep
-                        callback(count, total_count)
+                    for ff, freq in enumerate(s.frequency.data):
+                        if callback is not None:
+                            # report progress during sweep
+                            callback(count, total_count)
 
-                    self.set_output(frequency=freq, power=-5)
-                    self.sdr.rx_destroy_buffer()
-                    self.sdr.rx_lo = int(freq)
-                    self.sdr.rx_enabled_channels = [0, 1]
-                    self.sdr.gain_control_mode_chan0 = "manual"
-                    self.sdr.gain_control_mode_chan1 = "manual"
-                    self.sdr.rx_hardwaregain_chan0 = 40
-                    self.sdr.rx_hardwaregain_chan1 = 40
-                    rx = self.sdr.rx()
-                    s.loc[dict(frequency=freq, m=m, n=n)] = np.mean(rx[1] / rx[0])
+                        self.set_output(frequency=freq, power=-5)
+                        self.sdr.rx_destroy_buffer()
+                        self.sdr.rx_lo = int(freq)
+                        self.sdr.rx_enabled_channels = [0, 1]
+                        self.sdr.gain_control_mode_chan0 = "manual"
+                        self.sdr.gain_control_mode_chan1 = "manual"
+                        self.sdr.rx_hardwaregain_chan0 = 40
+                        self.sdr.rx_hardwaregain_chan1 = 40
+                        rx = self.sdr.rx()
+                        s.loc[dict(frequency=freq, m=m, n=n)] = np.mean(rx[1] / rx[0])
 
-                    count += 1
+                        count += 1
 
         if callback is not None:
             # mark capture as complete
@@ -350,6 +361,92 @@ class Charon:
 
         return s
 
+    def calibrate_sol(self, prompt: Callable[[str], None] | None = None, **kwargs) -> None:
+        if len(self.ports) != 1:
+            raise ValueError(
+                f"SOL calibration needs only one port but {len(self.ports)} ports are enabled. "
+                "Did you mean to use SOLT?"
+            )
+
+        if prompt is None:
+            prompt = lambda s: input(f"{s}\nENTER to continue...")
+
+        ideal = rf.media.DefinedGammaZ0(frequency=rf.media.Frequency.from_f(self.frequency, unit="Hz"))
+        ideals = [ideal.short(), ideal.open(), ideal.load(0)]
+
+        names = ["short", "open", "load"]
+
+        measured = list()
+        for name in names:
+            prompt(f"Connect standard {name} to port {self.ports[0]}")
+            measured.append(self.capture(**kwargs))
+
+        cal = rf.OnePort(measured=[s2net(m) for m in measured], ideals=ideals)
+
+        self.calibration = cal
+
+    def calibrate_solt(self, prompt: Callable[[str], None] | None = None, **kwargs) -> None:
+        if len(self.ports) < 2:
+            raise ValueError(
+                f"SOLT calibration needs at least two ports but {len(self.ports)} ports are enabled. "
+                "Did you mean to use SOL?"
+            )
+
+        if len(self.ports) > 2:
+            raise NotImplementedError("SOLT calibration with more than two ports not yet supported")
+
+        if prompt is None:
+            prompt = lambda s: input(f"{s}\nENTER to continue...")
+
+        ideal = rf.media.DefinedGammaZ0(frequency=rf.media.Frequency.from_f(self.frequency, unit="Hz"))
+        ideals = [ideal.short(), ideal.open(), ideal.load(0)]
+        ideals = [rf.two_port_reflect(id, id) for id in ideals]
+
+        thru = np.zeros((len(self.frequency), 2, 2), dtype=np.complex128)
+        thru[:, 0, 1] = 1
+        thru[:, 1, 0] = 1
+        thru = rf.Network(frequency=self.frequency, f_unit="Hz", s=thru)
+
+        ideals.append(thru)
+
+        names_1p = ["short", "open", "load"]
+        names_2p = ["thru"]
+
+        measured = list()
+        for name in names_1p:
+            measured_param = list()
+            for port in self.ports:
+                prompt(f"Connect standard {name} to port {port}")
+                measured_param.append(self.capture(measurements=[(port, port)], **kwargs).sel(m=port, n=port))
+            measured.append(rf.two_port_reflect(*[s2net(m) for m in measured_param]))
+
+        for name in names_2p:
+            prompt(f"Connect standard {name} between ports {self.ports[0]} and {self.ports[1]}")
+            measured.append(s2net(self.capture(**kwargs)))
+
+        cal = rf.SOLT(measured=measured, ideals=ideals)
+
+        self.calibration = cal
+
+    def save_calibration(self, path: Path | str):
+        path = Path(path)
+        if path.suffix.lower() == ".pkl":
+            with open(str(path), "wb") as f:
+                pickle.dump(self.calibration, f)
+        else:
+            raise NotImplementedError(f"Unknown calibration file extension: {path.suffix}")
+
+    def load_calibration(self, path: Path | str):
+        path = Path(path)
+        if path.suffix.lower() == ".pkl":
+            with open(str(path), "rb") as f:
+                cal = pickle.load(f)
+                if not isinstance(cal, rf.calibration.Calibration):
+                    raise ValueError(f"Expected {rf.calibration.Calibration}, got {type(cal)}")
+                self.calibration = cal
+        else:
+            raise NotImplementedError(f"Unknown calibration file extension: {path.suffix}")
+
 
 # %%
 if __name__ == "__main__":

charon_vna/vna_dev.py

@@ -2,10 +2,11 @@
 import numpy as np
 from matplotlib import pyplot as plt
 
+from charon_vna.util import db20, net2s, s2net
 from charon_vna.vna import Charon
 
 # %%
-frequency = np.linspace(80e6, 280e6, 31)
+frequency = np.linspace(80e6, 280e6, 301)
 
 # %%
 vna = Charon(frequency=frequency, ports=2)
@@ -16,9 +17,55 @@ s = vna.capture()
 # %%
 for m in s.m.data:
     for n in s.n.data:
-        plt.plot(s.frequency, 20 * np.log10(np.abs(s.sel(m=m, n=n))), label="$S_{" + str(m) + str(n) + "}$")
+        plt.plot(s.frequency, db20(s.sel(m=m, n=n)), label="$S_{" + str(m) + str(n) + "}$")
 plt.grid(True)
 plt.legend()
+plt.show()
 
 
+# %%
+vna.calibrate_sol()
+
+# %%
+vna.calibrate_solt()
+
+# %%
+vna.save_calibration("./calibration.pkl")
+
+# %%
+vna.load_calibration("./calibration.pkl")
+
+# %%
+s2 = net2s(vna.calibration.apply_cal(s2net(s)))
+# s2.coords["m"] = s.m
+# s2.coords["n"] = s.n
+
+for m in s.m.data:
+    for n in s.n.data:
+        plt.plot(s.frequency, db20(s.sel(m=m, n=n)), label="$S_{" + str(m) + str(n) + "}$ (uncalibrated)")
+        plt.plot(s2.frequency, db20(s2.sel(m=m, n=n)), label="$S_{" + str(m) + str(n) + "}$ (calibrated)")
+plt.grid(True)
+plt.legend()
+plt.ylabel("Magnitude [dB]")
+# plt.ylim(-30, 5)
+plt.show()
+
+for m in s.m.data:
+    for n in s.n.data:
+        if m != n:
+            plt.plot(
+                s.frequency,
+                np.angle(s.sel(m=m, n=n), deg=True),
+                label="$S_{" + str(m) + str(n) + "}$ (uncalibrated)",
+            )
+            plt.plot(
+                s2.frequency,
+                np.angle(s2.sel(m=m, n=n), deg=True),
+                label="$S_{" + str(m) + str(n) + "}$ (calibrated)",
+            )
+plt.grid(True)
+plt.legend()
+plt.ylabel("Phase [deg]")
+plt.show()
+
 # %%