Port 1940: JetVision Client — The Aircraft Tracker's Data Port

What Port 1940 Does

Port 1940 is registered to jvclient, the JetVision Client Port. JetVision is a German company that builds ADS-B receivers — hardware that passively listens to radio signals broadcast by commercial aircraft and decodes their position, altitude, speed, and identity in real time.

Port 1940 is how JetVision's client software connects to and retrieves data from these receivers.

What ADS-B Is

ADS-B stands for Automatic Dependent Surveillance-Broadcast. Modern aircraft continuously broadcast their GPS-derived position on 1090 MHz radio frequency. Any receiver within range can hear it. No handshake required, no permission needed — the planes are just announcing themselves to the sky.

JetVision built hardware (most notably the Radarcape) that captures these broadcasts, decodes the raw signals, and exposes the data over a network. Port 1940 is part of how that data gets from the receiver to the software consuming it.¹

The Range This Port Lives In

Port 1940 sits in the registered port range (1024-49151). These are ports that anyone can request registration for from IANA. Registration doesn't mean the port is exclusively yours on the Internet — it means your name is in the registry and others are expected to avoid conflicts. IANA recorded jvclient here with a named contact.²

It's worth noting: registered ports aren't policed. Any application can bind to any of these ports on your machine. The registry is a coordination mechanism, not an access control system.

JetVision and the Flight Tracking Ecosystem

JetVision's Radarcape receivers feed data into the flight tracking services people actually use. Their hardware is used by serious enthusiasts and professional operators who contribute data upstream — and port 1940 is where a client application reaches into one of these receivers to pull what it needs.³

The scale is quietly remarkable: a low-cost antenna and a small Linux board on a rooftop, decoding the position of every plane in range, serving it over a local port, feeding global maps where millions of people track flights in real time. Port 1940 is one data handoff in that chain.

How to Check If Port 1940 Is Active on Your System

To see what process, if anything, is listening on port 1940:

macOS / Linux:

lsof -i :1940

or

ss -tlnp | grep 1940

Windows:

netstat -ano | findstr :1940

If nothing is returned, nothing is using the port. If something appears, the process name or PID will tell you what it is.