calibration

CHANGELOG.md

@@ -4,6 +4,16 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased] - DATE
+
+### Changed
+
+* The default output power interlock threshold has been increased from 0 dBm to 20 dBm.
+
+### Added
+
+* Booster CLI tool support for power transform calibrations.
+
 ## [0.6.0] - 2024-08-28
 
 ### Changed

py/booster/__init__.py

@@ -9,6 +9,7 @@
 import json
 import enum
 import logging
+import sys
 
 import miniconf
 from aiomqtt import MqttError
@@ -45,7 +46,6 @@ def __init__(self, client, prefix):
             client: A connected MQTT5 client.
             prefix: The prefix of the booster to control.
         """
-        self.prefix = prefix
         self.miniconf = miniconf.Miniconf(client, prefix)
 
     async def perform_action(self, action: Action, channel: str):
@@ -58,16 +58,11 @@ async def perform_action(self, action: Action, channel: str):
         Returns:
             The received response to the action.
         """
-        message = json.dumps(
-            {
-                "channel": CHANNEL[channel],
-            }
-        )
+        message = json.dumps({"channel": CHANNEL[channel]})
 
-        response = await self.miniconf._do(
-            f"{self.prefix}/command/{action.value}", payload=message
+        return await self.miniconf._do(
+            f"{self.miniconf.prefix}/command/{action.value}", payload=message
         )
-        return json.loads(response[0])
 
     async def tune_bias(self, channel, current):
         """Set a booster RF bias current.
@@ -86,9 +81,10 @@ async def tune_bias(self, channel, current):
 
         async def set_bias(voltage):
             await self.miniconf.set(f"/channel/{channel}/bias_voltage", voltage)
-            # Sleep 100 ms for bias current to settle and for ADC to take current measurement.
+            # Sleep 200 ms for bias current to settle and for ADC to take current measurement.
             await asyncio.sleep(0.2)
             response = await self.perform_action(Action.ReadBiasCurrent, channel)
+            response = json.loads(response[0])
             vgs, ids = response["vgs"], response["ids"]
             print(f"Vgs = {vgs:.3f} V, Ids = {ids * 1000:.2f} mA")
             return vgs, ids
@@ -128,3 +124,122 @@ async def set_bias(voltage):
                 break
 
         return vgs, ids
+
+    async def calibrate(self, channel, transform):
+        """Calibrate a linear transform.
+
+        Args:
+            channel: The channel to calibrate the transform on.
+            transform: The transform to calibrate (input, output, reflected)
+
+        Returns:
+            The transform
+        """
+        backup = {}
+        for k in f"/channel/{channel}/state /telemetry_period".split():
+            backup[k] = json.loads(await self.miniconf.get(k))
+
+        try:
+            print(
+                f"""Calibrating the `{transform}` power detector linear transform on channel {channel}.
+
+The transform calibration routine requires two different operating powers.
+For optimal accuracy, they should support the desired operating power range
+and both be at the same input signal carrier frequency representative of the
+desired operating frequency range.
+
+For each power condition, establish it, determine the true power by measuring it and
+input it at the prompt. The routine determines the apparent power and computes a new
+corrected transform."""
+            )
+            await self.miniconf.set(f"/channel/{channel}/state", "Enabled")
+            await asyncio.sleep(0.4)
+            await self.miniconf.set(f"/telemetry_period", 1)
+
+            # This is merely to avoid the queue full warnings
+            # and the inconvenient async-iterator-only interface of aiomqtt
+            queue = asyncio.Queue(1)
+
+            async def tele():
+                async with miniconf.Client(
+                    self.miniconf.client._hostname,
+                    protocol=miniconf.MQTTv5,
+                ) as tele:
+                    topic = f"{self.miniconf.prefix}/telemetry/ch{channel}"
+                    await tele.subscribe(topic)
+                    try:
+                        async for msg in tele.messages:
+                            try:
+                                queue.put_nowait(msg)
+                            except asyncio.QueueFull:
+                                continue
+                    except asyncio.CancelledError:
+                        pass
+                    finally:
+                        await tele.unsubscribe(topic)
+
+            cal = []
+            async with asyncio.TaskGroup() as tg:
+                tele = tg.create_task(tele())
+                for i in range(2):
+                    while True:
+                        try:
+                            true = float(
+                                await ainput(
+                                    f"Enter current true `{transform}` power in dBm:"
+                                )
+                            )
+                            break
+                        except ValueError as e:
+                            print(f"Error: {e}, try again")
+                    while True:
+                        try:
+                            queue.get_nowait()
+                        except asyncio.QueueEmpty:
+                            break
+                    msg = json.loads((await queue.get()).payload)
+                    if (
+                        msg["reflected_overdrive"]
+                        or msg["output_overdrive"]
+                        or msg["alert"]
+                        or msg["state"] != "Enabled"
+                    ):
+                        raise ValueError(
+                            "Channel tripped, overdriven, or in alert condition: ", msg
+                        )
+                    apparent = msg[f"{transform}_power"]
+                    print(f"Current apparent `{transform}` power: {apparent} dBm")
+                    cal.append((apparent, true))
+                tele.cancel()
+
+            current = json.loads(
+                await self.miniconf.get(
+                    f"/channel/{channel}/{transform}_power_transform"
+                )
+            )
+            print(f"Current `{transform}` transform: {current}")
+            (qa, pa), (qb, pb) = cal
+            pm = (pa + pb) / 2
+            qm = (qa + qb) / 2
+            dpdq = (pa - pb) / (qa - qb)
+            new = dict(
+                slope=dpdq * current["slope"],
+                offset=pm + dpdq * (current["offset"] - qm),
+            )
+            print(f"Proposed new `{transform}` transform: {new}")
+            if await ainput("Enter `y` to set new transform:") == "y":
+                await self.miniconf.set(
+                    f"/channel/{channel}/{transform}_power_transform", new
+                )
+                print("Set (use `save` to write to flash memory)")
+            else:
+                print("Not set")
+
+        finally:
+            for k, v in backup.items():
+                await self.miniconf.set(k, v)
+
+
+async def ainput(string: str) -> str:
+    print(string, end=" ", flush=True)
+    return (await asyncio.to_thread(sys.stdin.readline)).rstrip("\n")

py/booster/__main__.py

@@ -6,11 +6,10 @@
 """
 import argparse
 import asyncio
+import logging
 
 from . import Booster, Action
 import miniconf
-import logging
-
 
 # A dictionary of all the available commands, their number of arguments, argument type, and help
 # information about the command.
@@ -24,6 +23,11 @@
         "type": float,
         "help": "Tune the channel RF drain current to the specified amps",
     },
+    "calibrate": {
+        "nargs": 1,
+        "type": str,
+        "help": "Calibrate a transform (input, output, or reflected)",
+    }
 }
 
 
@@ -113,9 +117,10 @@ async def channel_configuration(args):
                     print(
                         f"Channel {args.channel}: Vgs = {vgs:.3f} V, Ids = {ids * 1000:.2f} mA"
                     )
+                elif command == "calibrate":
+                    await booster.calibrate(args.channel, cmd_args[0])
 
-    loop = asyncio.get_event_loop()
-    loop.run_until_complete(channel_configuration(parser.parse_args()))
+    asyncio.run(channel_configuration(parser.parse_args()))
 
 
 if __name__ == "__main__":

src/settings/eeprom/rf_channel.rs

@@ -77,39 +77,50 @@ impl DecodeOwned for ChannelState {
 /// Represents booster channel-specific configuration values.
 #[derive(Tree, Encode, DecodeOwned, Debug, Copy, Clone, PartialEq)]
 pub struct ChannelSettings {
+    // dBm
     #[tree(validate=Self::validate_output_interlock)]
     pub output_interlock_threshold: f32,
+
+    // V
     #[tree(validate=Self::validate_bias_voltage)]
     pub bias_voltage: f32,
+
     pub state: ChannelState,
+
     pub input_power_transform: LinearTransformation,
+
     pub output_power_transform: LinearTransformation,
+
     pub reflected_power_transform: LinearTransformation,
 }
 
 impl Default for ChannelSettings {
     /// Generate default booster channel data.
     fn default() -> Self {
         Self {
-            output_interlock_threshold: 0.0,
+            // dBm
+            output_interlock_threshold: 20.0,
+
+            // V
             bias_voltage: -3.2,
+
             state: ChannelState::Off,
 
             // When operating at 100MHz, the power detectors specify the following output
-            // characteristics for -10 dBm to 10 dBm (the equation uses slightly different coefficients
-            // for different power levels and frequencies):
+            // characteristics for -10 dBm to 10 dBm:
             //
             // dBm = V(Vout) / .035 V/dB - 35.6 dBm
             //
             // All of the power meters are preceded by attenuators which are incorporated in
             // the offset.
             output_power_transform: LinearTransformation::new(1.0 / 0.035, -35.6 + 19.8 + 10.0),
-            // The input power and reflected power detectors are then passed through an
-            // op-amp with gain 1.5x - this modifies the slope from 35mV/dB to 52.5mV/dB
+
+            // The input power and reflected power detectors have an op-amp gain of 1.5
             reflected_power_transform: LinearTransformation::new(
                 1.0 / 1.5 / 0.035,
                 -35.6 + 19.8 + 10.0,
             ),
+
             input_power_transform: LinearTransformation::new(1.0 / 1.5 / 0.035, -35.6 + 8.9),
         }
     }
@@ -131,8 +142,7 @@ impl ChannelSettings {
         }
 
         // Verify the interlock is mappable to a DAC threshold.
-        let output_interlock_voltage = self.output_power_transform.invert(new);
-        if !(0.00..=ad5627::MAX_VOLTAGE).contains(&output_interlock_voltage) {
+        if !(0.0..=ad5627::MAX_VOLTAGE).contains(&self.output_power_transform.invert(new)) {
             return Err("Output interlock threshold voltage out of range");
         }