diff --git a/python/protocan/trends.py b/python/protocan/trends.py
index 94c67fa..71b6f38 100644
--- a/python/protocan/trends.py
+++ b/python/protocan/trends.py
@@ -54,6 +54,8 @@ class TrendSignal:
     deviceType: int = 7
     device: int = 13
     byteOffset: int = 0
+    multiplier: float = 1.0
+    iq: int = 0
     extended: bool = True
 
     @classmethod
@@ -72,9 +74,11 @@ class TrendSignal:
         for field in ("id", "name", "source", "address", "color", "valueType"):
             if type(getattr(self, field)) is not str:
                 raise ValueError(f"{field} must be a string")
-        for field in ("order", "deviceType", "device", "byteOffset"):
+        for field in ("order", "deviceType", "device", "byteOffset", "iq"):
             if type(getattr(self, field)) is not int:
                 raise ValueError(f"{field} must be an integer")
+        if type(self.multiplier) not in (int, float) or not math.isfinite(self.multiplier):
+            raise ValueError("multiplier must be a finite number")
         if type(self.visible) is not bool or type(self.extended) is not bool:
             raise ValueError("Visibility and CAN format must be boolean")
         if not self.id.strip() or len(self.id) > 80 or not 1 <= self.order <= 9999:
@@ -98,6 +102,11 @@ class TrendSignal:
             raise ValueError("Invalid ProtoCAN device")
         if self.source == "CAN_RAW" and not 0 <= self.byteOffset <= 6:
             raise ValueError("Word offset must be 0..6")
+        if not 0 <= self.iq <= 30:
+            raise ValueError("IQ must be 0..30")
+
+    def display_value(self, raw_value: float) -> float:
+        return raw_value * self.multiplier / (1 << self.iq)
 
 def validate_settings(settings: Mapping[str, list[TrendSignal]]) -> None:
     ids = set()
@@ -132,14 +141,15 @@ def decode_settings(text: str) -> dict[str, list[TrendSignal]]:
         raise ValueError("profiles must be an object")
     result = {}
     fields = set(TrendSignal.__dataclass_fields__)
+    required_fields = fields - {"multiplier", "iq"}
     for profile, items in profiles.items():
         if not isinstance(items, list) or len(items) > MAX_SIGNALS:
             raise ValueError("Expected up to 64 signals")
         signals = []
         for item in items:
-            if not isinstance(item, dict) or not fields <= item.keys():
+            if not isinstance(item, dict) or not required_fields <= item.keys():
                 raise ValueError("Missing signal fields")
-            signals.append(TrendSignal(**{key: item[key] for key in fields}))
+            signals.append(TrendSignal(**{key: item[key] for key in fields if key in item}))
         result[profile] = signals
     validate_settings(result)
     return result
diff --git a/python/tests/test_trends.py b/python/tests/test_trends.py
index 9a82963..3613823 100644
--- a/python/tests/test_trends.py
+++ b/python/tests/test_trends.py
@@ -14,6 +14,16 @@ FIXTURE = Path(__file__).resolve().parents[2] / "c/set-protocol/tests/fixtures/t
 
 
 class TrendTests(unittest.TestCase):
+    def test_multiplier_and_iq_scale_display_and_old_json_defaults(self):
+        signal = TrendSignal("scaled", multiplier=2.5, iq=3)
+        self.assertEqual(10.0, signal.display_value(32.0))
+        signal.validate("TMS2812")
+        payload = json.loads(encode_settings({"TMS2812": [signal]}))
+        payload["profiles"]["TMS2812"][0].pop("multiplier")
+        payload["profiles"]["TMS2812"][0].pop("iq")
+        restored = decode_settings(json.dumps(payload))["TMS2812"][0]
+        self.assertEqual((1.0, 0), (restored.multiplier, restored.iq))
+
     def test_shared_kotlin_fixture_and_round_trip(self):
         settings = decode_settings(FIXTURE.read_text(encoding="utf-8"))
         self.assertEqual(5, sum(map(len, settings.values())))