node-red-contrib-ibeacon-kalman/README.md

Kalman filter for iBeacon RSSI distance estimation

# node-red-contrib-ibeacon-kalman

A Node-RED node for iBeacon distance estimation using Kalman filtering.

## Installation

```bash
npm install node-red-contrib-ibeacon-kalman
```

Or install via the Node-RED Palette Manager.

## Features

- Converts RSSI to distance using log-distance path loss model
- Implements Kalman filtering for smooth distance estimates
- Configurable parameters:
  - TX Power (RSSI at 1m)
  - Path loss exponent (n)
  - Process noise
  - Measurement noise

## Usage

1. Add the node to your flow
2. Configure the parameters:
   - **TX Power**: RSSI value at 1 meter distance (typically -59 dBm)
   - **Path Loss Exponent**: Environment factor (2.0 for free space)
   - **Process Noise**: How quickly the filter adapts (default 0.1)
   - **Measurement Noise**: RSSI measurement variance (default 1.0)

## Input

- `msg.payload`: RSSI value in dBm (number)

## Output

```javascript
{
  rssi: -70,             // Input RSSI value
  rawDistance: 3.16,      // Unfiltered distance estimate
  filteredDistance: 2.87  // Kalman-filtered distance
}
```
## Dynamic TX Power Configuration

You can override the configured TX Power per-message:

```javascript
msg.txPower = -62; // dBm
```

When TX Power changes:
1. Kalman filter will automatically reset
2. New value will be used for distance calculation
3. Applied TX Power included in output message

## Dynamic Parameters

You can override these parameters per-message:

| Parameter    | Type   | Default | Description                      |
|--------------|--------|---------|----------------------------------|
| `txPower`    | number | -59     | RSSI at 1m distance (dBm)        |
| `nValue`     | number | 2.0     | Path loss exponent (1.0-5.0)     |

```javascript
// Пример динамического изменения
msg.txPower = -62; // Для конкретного маяка
msg.nValue = 2.3;  // Для среды с препятствиями
```

When parameters change:
1. Kalman filter automatically resets
2. New values are used for calculations
3. All parameters included in output message

{
  "payload": -65,
  "txPower": -58,
  "nValue": 3.0,
  "topic": "beacon/kitchen"
}

## License

MIT