868MHz LoRa Waterfall (ct125)
2026-09-27
An RTL-SDR dongle running OpenWebRX+ watches a 2 MHz slice of the 868 MHz ISM band (868.5 to 870.5 MHz), where LoRa mesh networks such as MeshCore, Meshtastic and Reticulum transmit. A small collector joins the OpenWebRX+ server as an ordinary, strictly read-only listener, receives the same compressed spectrum frames a web browser would, decodes them and keeps the last 15 minutes in a ring buffer in memory at 488 Hz per bin. Every time the NomadNet page 52691017fd8dafdc48c7e53914f96f7f is requested, a script turns that buffer into a Micron picture: each character cell is one time and frequency slot, coloured by signal strength and drawn with braille dots or block characters, so packets appear as bright bursts scrolling down the page. Nothing is filtered or squelched: the colour scale is taken from the data itself, so the strongest signal in view always reaches the top of the palette and weak ones stay visible. Buttons on the page change the zoom, render style and brightness, and an auto-refreshing view (NomadNet and MeshChatX browsers only) redraws the picture every 10 seconds.
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