js-otdr 📡

A lightweight, zero-dependency TypeScript/JavaScript library for parsing Telcordia SR-4731 Optical Time Domain Reflectometer (.sor) binary files.

🚀 Features

• ⚡ Fast & Lightweight: Zero runtime dependencies.
• 📦 Dual Module & Browser Support: Works in ESM, CommonJS, and Browser environments (Node.js & Web).
• 🧩 Complete Standard Block Support: Parses GenParams, SupParams, FxdParams, KeyEvents, DataPts, and Cksum blocks according to Telcordia SR-4731 specifications.
• 🔒 Integrity Verification: Automatic CRC-16 checksum validation for parsed SOR files.
• 📄 JSON Export: Convenient .toJson() serialization with formatting options.
• 🛠️ CLI Tool Included: Convert .sor files to .json directly from the command line.
• 🟦 Fully Typed: Written in TypeScript with exportable interfaces and types.

📦 Installation

npm install @diolan12/js-otdr

or with yarn / pnpm / bun:

yarn add @diolan12/js-otdr
# or
pnpm add @diolan12/js-otdr
# or
bun add @diolan12/js-otdr

CDN (Browser <script> Tag)

Include @diolan12/js-otdr directly in the browser via jsDelivr or unpkg:

Via IIFE (<script> tag with global JsOtdr):

<script src="https://cdn.jsdelivr.net/npm/@diolan12/js-otdr/dist/index.global.js"></script>
<script>
  // Access via global JsOtdr namespace
  const parser = new JsOtdr.SorParser(arrayBuffer);
  const sorData = parser.parse();
  console.log(sorData.GenParams.cableId);
  console.log(sorData.toJson(true));
</script>

Via ES Module (<script type="module">):

<script type="module">
  import { SorParser } from 'https://cdn.jsdelivr.net/npm/@diolan12/js-otdr/+esm';

  const parser = new SorParser(arrayBuffer);
  const sorData = parser.parse();
</script>

💻 Usage

1. Basic Parsing

Pass an ArrayBuffer to SorParser to extract structured OTDR metadata:

import { SorParser } from '@diolan12/js-otdr';
import * as fs from 'node:fs';

// Read SOR binary file in Node.js
const fileBuffer = fs.readFileSync('trace.sor');
const arrayBuffer = fileBuffer.buffer.slice(
  fileBuffer.byteOffset,
  fileBuffer.byteOffset + fileBuffer.byteLength
);

// Instantiate parser and parse
const parser = new SorParser(arrayBuffer);
const sorData = parser.parse();

// Access parsed block metadata
console.log(`Cable ID: ${sorData.GenParams.cableId}`);
console.log(`Wavelength: ${sorData.FxdParams.wavelengthNm} nm`);
console.log(`Pulse Width: ${sorData.FxdParams.pulseWidthNs} ns`);
console.log(`OTDR Supplier: ${sorData.SupParams.supplier}`);
console.log(`Events Count: ${sorData.KeyEvents.numEvents}`);
console.log(`Checksum Valid: ${sorData.Cksum.isValid}`);

2. Accessing Key Events & Data Points

Iterate over events detected along the fiber trace:

// Access individual key events
sorData.KeyEvents.events.forEach((event) => {
  console.log(
    `Event #${event.eventNumber}: ${event.eventType} at ${event.distanceKm} km (Loss: ${event.spliceLossDb} dB, Reflectance: ${event.reflectionLossDb} dB)`
  );
});

// Access trace summary
const { totalLossDb, orlDb } = sorData.KeyEvents.summary;
console.log(`Total Loss: ${totalLossDb} dB, Optical Return Loss: ${orlDb} dB`);

// Access trace dB values array for plotting
const dbPoints = sorData.DataPts.dbPoints; // Float32Array of loss values in dB

3. Exporting to JSON (toJson)

Convert parsed OTDR data into a JSON string:

const parser = new SorParser(arrayBuffer);

// Format with 2-space indentation
const prettyJson = parser.toJson(true);
console.log(prettyJson);

// Compact JSON string from SorData
const sorData = parser.parse();
const compactJson = sorData.toJson(false);

🖥️ Command Line Interface (CLI)

The package includes a CLI utility to convert .sor files to .json directly:

# Process a .sor file and save output to trace.json
npx @diolan12/js-otdr -i trace.sor -o trace.json

# Or run via script in local repository
npm run cli -- -i tests/fixtures/yokogawa.sor -o output.json

📚 API Reference

SorParser

class SorParser {
  constructor(buffer: ArrayBuffer);
  
  // Parses the buffer and returns a SorData instance
  public parse(): SorData;
  
  // Converts parsed SOR data directly into JSON string
  public toJson(pretty?: boolean): string;
}

SorData

SorData encapsulates all standard Telcordia SR-4731 blocks:

class SorData implements SorMetadata {
  GenParams: GenParamsData;   // General parameters (cable ID, fiber type, location, etc.)
  SupParams: SupParamsData;   // Supplier parameters (manufacturer, OTDR model, software, etc.)
  FxdParams: FxdParamsData;   // Fixed parameters (wavelength, pulse width, IOR, trace length, data points, etc.)
  KeyEvents: KeyEventsData;   // Event table and summary metrics (splice loss, reflectance, ORL, etc.)
  DataPts: DataPtsData;       // Raw and scaled data points (Uint16Array & Float32Array)
  Cksum: CksumData;           // Checksum validation result (stored vs calculated CRC-16)

  // Serializes all block data to JSON string
  public toJson(pretty?: boolean): string;

  // Returns plain JavaScript object containing all block data
  public toObject(): SorMetadata;
}

🧪 Testing & Development

Unit tests are written using Vitest.

# Run unit test suite
npm test

# Run tests in watch mode during development
npm run test:watch

# Build package outputs (ESM, CJS, IIFE, DTS)
npm run build

📄 License

This project is licensed under the MIT License.