Getting Started

This guide goes from installing the SimTX desktop app to a first transmission and listening to it. TX means transmit and RX means receive.

1. Install the app

Download the app from the SimTX downloads page:

• Windows: the 64-bit .exe installer.
• macOS: the .dmg for Apple Silicon. The first time, right-click the app and choose Open to get past the macOS security warning.
• Linux: .deb, .rpm, Arch or Void packages, or an AppImage. The install page explains how to add the package repository. Ubuntu 24.04 or Debian 13 or newer is needed.

2. Sign in and connect

1. Open the app. In Sign in to SimTX, press Sign in.
2. Press Open browser, sign in to your SimTX account and approve the device. Copy link copies the address instead.
3. In Connect to a server, choose a Server and press Connect.

The top right of the window then shows the server and Connected. Work offline opens the app without connecting.

3. Create your first station

A station holds your callsign, location, antennas and radios. On first start, the in-app getting started guide points at each control in turn.

1. In the Transmit tab, press Create a station.
2. Under Basics, enter a Name and your Callsign.
3. Under Location, press Pick on globe, click where the station stands and press Done.
4. Under Antennas, open the dipole and set the length to 31 m and the Height to 10 m. This suits the frequency below.
5. Press Create station.

The station now shows under Transmit from. See Stations.

4. Make a first transmission

In the Transmit tab:

1. Set Frequency to 4625 with the unit kHz, and Power (W) to 100.
2. Choose the Modulation AM Double Sideband Full Carrier and tick Auto beside Bandwidth (Hz).
3. Under Source, choose Audio file, press Choose… and pick a short audio file.
4. Press Start TX.

The session appears in the Sessions list as Running. Queued means every transmitter slot is taken; it starts by itself when one is free. Select the session to see the Radio deck meters. Listen to own TX plays your signal as transmitted. Stop ends it.

Transmitting covers every control. If the session fails, its message says why; see Troubleshooting.

5. Receive

You need an SDR program that supports rtl_tcp, such as SDR++.

1. Open the Receive tab. Under Where you listen, choose My station, Public station, or Ad-hoc for any location without an account.
2. Set the Center frequency to 4625 kHz and the Sample rate (Hz) to 250000.
3. Press Start RX.
4. In your SDR program, connect an rtl_tcp source to 127.0.0.1:1234 and tune to 4625 kHz in AM.

How to receive shows the settings in SDR++, and Receiving covers every receive control. Propagation Basics explains how distance, band and time of day change what a receiver hears.

Continue from here

• SimTX Guide: all user guides.
• Transmission Sources: microphones, streams and other sources.
• Modulation Modes: choosing a mode.
• Antenna System: changing frequency and choosing an antenna.
• Lua extensions: extensions and themes.