Lynx RPi5 Dual RX

Lynx and Knobler

Lynx is a full DATV receiver for the Raspberry Pi 5 — not a control panel bolted onto someone else's decoder, but the whole receive chain: tuning, decoding, a genuine live picture on screen, and, when you want it, real diversity reception — two independent tuner inputs combined automatically, so a fade on one path doesn't have to mean losing the shot. Pair it with Knobler, its companion rotary-dial remote built on the M5Stack M5Dial, and you've got a receiver you can actually run from across the room — glance at it, spin the dial, get on with your day.

It's actively developed, and it already does three genuinely different jobs well: a QO-100 ground station, a repeater input receiver, or a straightforward home DATV set-top box — same software, same interface, whichever one you're actually building.

Requires a Raspberry Pi 5 (4GB or better). It won't run on a Pi 4 — the decode workload genuinely needs the newer hardware.

This page gives a brief overview of both. See Getting Started below for setup instructions.

Get Started

Ready to get something on screen? Here's everything you need.

• Lynx — source code, install guide, and full documentation
• Knobler — source code
• New to Lynx? The Installation Guide takes you from a blank SD card to a working receiver in one sitting, including a one-line installer.

Lynx

Built around the Picotuner, Lynx gives you a full receiver, not just a viewer:

• A local web UI (default port 8080) for status, tuning, and configuration
• Live decode status — lock state, MER, and related quality metrics, read from the Picotuner's status broadcast
• A preset system for quickly recalling known frequencies/symbol rates across plugs (including saved presets created from the web UI)
• Optional receive diversity combining across two tuner inputs, with automatic MER-based switching and a "hard freeze breaker" safeguard against repeated lock loss
• Optional notifications — Slack, QRZ logbook lookups, and GPIO-triggered outputs (e.g. driving an external "on air" indicator) — each independently configurable and disabled by default
• Optional RTMP relay of the decoded stream

Configuration lives in a single YAML file covering site details (callsign, locator, location), the Picotuner connection, presets, streams, diversity settings, and notification integrations.

Full documentation, including an install guide, a Web UI reference, and a guide to the on-screen display, is kept alongside the source: docs folder on GitHub.

Knobler

Knobler is a physical companion display for Lynx, built on an M5Stack M5Dial — a small ESP32-based device with a round touchscreen and a rotary encoder. It polls Lynx's web API directly and gives you a dedicated, always-on physical readout and control surface, separate from the web UI.

Current capabilities:

• Live status display (lock state, signal quality) with a configurable poll interval
• A menu system for browsing and selecting presets and streams via the rotary encoder, with an auto-timeout back to the normal display
• Self-service Wi-Fi setup — no need to hardcode network credentials into the firmware or edit code to get it on your network (see below)
• Automatic discovery of the Lynx receiver on the local network — no need to hardcode or manually enter an IP address

Wi-Fi Setup

On first boot (or if it can't find a previously-saved network), Knobler opens a temporary Wi-Fi access point of its own and displays a short prompt on screen. Connecting a phone or laptop to that access point brings up a normal Wi-Fi configuration page, where you select your network from a list and type in the password on a proper keyboard — rather than fumbling through SSID entry on a 1.28" touchscreen.

Once configured, credentials are saved on the device. If the saved network ever becomes unreachable (moved out of range, router replaced, etc.), Knobler automatically falls back into setup mode after a short timeout, without any need to reflash or reconfigure it by hand.

Auto-Discovery

Rather than requiring a fixed, manually-entered IP address for the Lynx receiver, Knobler broadcasts a small discovery request on the local network on startup. Any Lynx instance running current software answers directly, providing its name, callsign, IP address, and API port — so Knobler finds the right receiver automatically, even if its address changes (e.g. after a router reboot hands out a new DHCP lease).

Getting Started

Requirements:

• An M5Stack M5Dial device and USB-C cable
• Arduino IDE, with ESP32/M5Stack board support and the required libraries (M5Dial, WiFiManager, ArduinoJson) installed
• A Lynx receiver running current software (the discovery responder must be present — see below)
• A computer or phone to complete Wi-Fi setup

Lynx: the Installation Guide covers everything from a blank SD card to a working receiver, including a one-line installer script.

Before flashing Knobler: make sure the Lynx receiver is running a version of the software that includes the discovery responder (it prints a line similar to Discovery responder listening on UDP :9998. on startup). Older Lynx installs will need updating first, or Knobler won't be able to find them automatically.

A full step-by-step Knobler installation guide — covering Arduino IDE setup, board/library installation, flashing, and first-time Wi-Fi configuration — is not yet published separately; for now, see the Knobler repository directly.

Status

Both projects are under active development. Known limitations at time of writing:

• If more than one Lynx receiver answers a discovery request on the same network, Knobler currently connects to whichever reply arrives first — a picker screen for choosing between multiple receivers is planned but not yet built.
• There is currently no on-device way to force Knobler back into Wi-Fi setup mode (e.g. to deliberately switch networks) short of clearing its saved credentials via a computer.

See Also

• Lynx source code and documentation on GitHub
• Knobler source code on GitHub
• Picotuner

Credits

Justin D. Cockett - G8YTZ