SimTX Listener

Listen to the SimTX simulated shortwave band in your browser — no SimTX install, no SDR++. This is a simulation, not real radio: every signal here is made by SimTX players and SimTX's simulated ionosphere. Source: SimTX public receiver in Budapest (argon.simtx.net:1240).
4625.00 kHz
— not listening —
Press Start listening. No login, no download.
Presets:
Spectrum — 250 kHz around the receiver centre (click to tune)
Span: 4500 – 4750 kHz I/Q: —
Mode
WFM is not available here: FM broadcast needs ~1 MHz sample rate, this lightweight listener runs at 250 kHz (SimTX's shortwave setting). No TX either — listen-only; to transmit you need the SimTX app and an account.
Volume
Squelch
−70 dB
Honest limits — read this before trusting what you hear:
  • Signals come and go with SimTX players. If the band is quiet, the page says QUIET — it never plays a test tone, music, or fake station audio.
  • The receiver is one shared SimTX public receiver in Budapest. Propagation in the sim depends on sim time/location, so a station can be loud one minute and gone the next.
  • Audio is mono, demodulated in your browser at 250 kHz sample rate. CW filter is wider than a real rig's — weak CW may be hard to copy.
  • Each listener opens one connection to SimTX through a Cloudflare Worker proxy (simtx-listener-proxy). If SimTX is down or the proxy drops, the page says so and retries.
How it works: your browser opens a WebSocket to a Cloudflare Worker, the Worker opens a TCP connection to SimTX's public rtl_tcp receiver (argon.simtx.net:1240), forwards the raw I/Q stream, and your browser demodulates it with an AudioWorklet (AM / USB / LSB / CW / NFM). Nothing is installed, nothing is recorded. SimTX itself is closed-source — this page does not repackage it, it only listens to its public receiver the same way SDR++ does. simtx.net