DP44/docs/ai/DTS Viewer/DTS.Viewer.Modules/DTS.Viewer.AddCalculatedChannel/Model.md

---
source_files:
  - DTS Viewer/DTS.Viewer.Modules/DTS.Viewer.AddCalculatedChannel/Model/CalculatedChannelCreator.cs
generated_at: "2026-04-17T15:59:43.455218+00:00"
model: "zai-org/GLM-5-FP8"
schema_version: 1
sha256: "0bdba55cc7806845"
---

# CalculatedChannelCreator Documentation

## 1. Purpose

The `CalculatedChannelCreator` class is a factory responsible for creating derived data channels from existing sensor input channels. It performs mathematical transformations—including 3D IR-TRACC displacement calculations, aggregate operations (SUM, AVE, Resultant, HIC), and binary operations (integration, differentiation, trigonometric functions)—on channel data and persists the results to memory-mapped files. This module exists to support post-processing of crash test data, enabling engineers to synthesize new measurement channels from raw sensor inputs.

---

## 2. Public Interface

### `CreateChannels` (static method)
```csharp
public static Test.Module.CalculatedChannel[] CreateChannels(
    string testId,
    string folder,
    Calculation calculation,
    List<Test.Module.Channel> inputChannels,
    string channelName,
    int startingNumber,
    List<Test.Module.Channel> allChannels,
    int clipLength,
    out List<string> errorList,
    int defaultEncoding)
```
**Behavior:** Main entry point for creating calculated channels. Dispatches to appropriate private methods based on the `Calculation` enum value. Returns an array of `Test.Module.CalculatedChannel` objects on success, or `null` if validation fails. Populates `errorList` with validation errors.

### `ValidateChannelName` (static method)
```csharp
public static bool ValidateChannelName(
    string channelName,
    List<Test.Module.Channel> inputChannels,
    List<Test.Module.Channel> allChannels,
    out List<string> errorList)
```
**Behavior:** Validates that the channel name is non-empty and unique across both input channels and all channels. Returns `true` if valid; `false` otherwise. If `allChannels` is `null`, validation is bypassed and returns `true`.

### `ThreeDIRTraccType` (public enum)
```csharp
public enum ThreeDIRTraccType
{
    Thorax,
    Abdomen,
    LowerThorax
}
```
**Behavior:** Specifies the anatomical location for 3D IR-TRACC calculations, which affects the constants (`δ` and `D0`) used in the displacement formulas.

---

## 3. Invariants

1. **Channel Number Offset:** All calculated channels use `ChannelNumberCalculationChannelIndicator` (constant value `100000`) as a base offset for their channel numbers.
2. **Sample Rate Compatibility:** For aggregate and 3D IR-TRACC operations, the maximum sample rate among input channels must be an integer multiple of each individual channel's sample rate. Otherwise, `NotSupportedException` is thrown.
3. **3D IR-TRACC Input Count:** `Create3DIRTraccChannels` asserts that exactly 3 input channels are provided.
4. **Aggregate Operation Input Count:** `CreateChannelsAggregateOperation` asserts that at least 2 input channels are provided (assertion message says "at least 1" but checks `1 < inputChannels.Count`).
5. **File Overwrite Safety:** `CreatePersistentInformationObject` deletes any existing file at the target filepath before creating a new persistent channel, using `GC.Collect()` followed by `FileUtils.DeleteFileOrMove`.
6. **Engineering Units Padding:** When persisting engineering units, the string is padded to even length for word-alignment if its length is odd.

---

## 4. Dependencies

### This Module Depends On:
- `DTS.Common.Enums.Sensors` - For `SensorConstants` (δ and D0 values)
- `DTS.Common.Utilities.Logging` - For `APILogger.Log`
- `DTS.Common.Utils` - For `FileUtils`
- `DTS.Serialization` - For `SliceRaw.File` format handling
- `DTS.Slice.Control` - Unclear specific usage (imported but no direct reference visible)
- `DTS.Common` - For `Constants.ADC_MIDPOINT`, `ZeroMethodType`
- `DTS.Common.Events` - For `PageErrorEvent`, `PageErrorArg`
- `DTS.Common.Calculations` - For `HeadInjuryCriterion`
- `DTS.Common.Utilities.Math.Nhtsa` - For `Integration`, `Differentiation`
- `Prism.Ioc` - For `ContainerLocator`
- `Prism.Events` - For `IEventAggregator`
- `Test.Module` namespace - For `Channel`, `CalculatedChannel`, `AnalogInputChannel`
- `Event.Module` namespace - For `Channel`, `AnalogInputChannel`

### What Depends On This Module:
- **Unclear from source alone** - No consumers are shown in this file.

---

## 5. Gotchas

### Critical Bugs Identified:

1. **Copy-Paste Error in `PerformCalculation` (line ~378):**
   ```csharp
   var stepRPot1 = Convert.ToInt32(Math.Ceiling(indexAtCurrentTimeIRTracc) - actualIndexAtCurrentTimeIRTracc);
   ```
   Uses `indexAtCurrentTimeIRTracc` instead of `indexAtCurrentTimeRPot1`. This causes incorrect interpolation for the R-Pot1 channel.

2. **Assignment Instead of Subtraction in `PerformCalculation` (line ~403):**
   ```csharp
   incrementRPot2 = (valueRPot2AtPoint = rPot2EUData[actualIndexAtCurrentTimeRPot2 - 1]) / rateRPot2;
   ```
   This is an assignment (`=`) inside parentheses, overwriting `valueRPot2AtPoint`, when it should be a subtraction (`-`).

3. **Unused Variable in `PerformCalculationsAggregate` (line ~151):**
   ```csharp
   var timeAtIndex =
   ```
   Variable is declared but never assigned or used. This is a syntax error or incomplete implementation.

### Non-Obvious Behaviors:

4. **Debug/Test Data Injection:** The method calls `DiskUtility.ReplaceDataIfNeeded(ref irTraccEUData, "DISPLEU.txt")` and similar for other channels. This appears to be a debug feature that can override channel data from disk files. Production behavior is unclear.

5. **Explicit `GC.Collect()` Call:** In `CreatePersistentInformationObject`, `GC.Collect()` is called before file deletion to handle file locks. This is a heavy operation that may cause performance issues.

6. **ScaleEuData Logic Appears Inverted:** When `max > short.MaxValue`, the scale factor calculation `scaleFactor = max / short.MaxValue` produces a value ≥ 1, which would amplify data that's already too large, potentially causing overflow when casting to `short`.

7. **HIC Unit Conversion:** For HIC calculations, if engineering units are not "g", the code multiplies by `9.80665` to convert from m/s² to g's. This assumes the input is in m/s², which may not always be true.

8. **Commented-Out Code:** There is a commented-out `DeleteChannelFile` method and associated logic for deferred file deletion, suggesting historical changes to file handling behavior.