Table of Contents
EMScope JavaScript API
JavaScript client library for the EMScope EMI measurement instrument (SW ≥ 4.1).
This is the browser counterpart of the Python api_v5.py client and follows the exact same wire protocol. Refer to the WebSocket API documentation for the full protocol description.
Legacy API — Software ≤ 3.13
The api.js and api_example.html files are provided for use with EMScope software versions 3.13 and earlier.
Required: a modern browser with native WebSocket support.
Current API — Software ≥ 4.1
The api_v5.js and api_example_v5.html files are provided for EMScope software version 4.1 and later.
Include api_v5.js in your HTML page. No external dependencies are required for browser use. Under Node.js, install the ws package and pass it via the WebSocketImpl option (see below).
The example file api_example_v5.html is a self-contained browser application with a live spectrum plot, configuration panel, and message log. Open it directly in a browser after setting the instrument IP address.
Connection model
Unlike the Python client (which uses an explicit receive loop), the JavaScript client is event-driven. The WebSocket connection opens automatically when the object is constructed. All incoming messages are delivered via the callback.
RBW / frequency bands
| Value | RBW | Frequency range | Standard |
|---|---|---|---|
| 200 | 200 Hz | 9 kHz – 150 kHz | CISPR 16-1-1 |
| 9 | 9 kHz | 150 kHz – 30 MHz | CISPR 16-1-1 |
| 120 | 120 kHz | 30 MHz – 110 MHz | CISPR 16-1-1 |
| 1 | 1 kHz | 10 kHz – 150 kHz | MIL-STD-461 |
| 10 | 10 kHz | 150 kHz – 30 MHz | MIL-STD-461 |
| 200_9 | dual | 9 kHz – 30 MHz | CISPR dual-band |
| 1_10 | dual | 10 kHz – 30 MHz | MIL dual-band |
Node.js
The library is compatible with Node.js. Install the ws package and pass it as the WebSocket implementation via the constructor options. See the source file for details.