GoEther-SDR

A Go-based SDR receiver inspired by gqrx, with a web UI for remote operation and single-binary deployment. Supports broadcast FM/AM/SSB/CW, ADS-B aircraft tracking, and Meteor-M LRPT weather satellite imagery. Tested with the RTL-SDR Blog V4 & V3 dongles (RTL2832U + R828D, TCXO, bias-tee, HF).

Features

• RTL-SDR Support — Built on go-rtl-sdr CGO bindings; multi-device support via a pluggable SDRDevice interface. Tested with the RTL-SDR Blog V4 dongle (RTL2832U + R828D tuner, TCXO, bias-tee, HF direct-sampling)
• Web UI — Vue 3 + Reka UI, embedded into the Go binary via //go:embed
• Real-time Spectrum & Waterfall — Canvas-rendered, streamed over WebSocket with configurable FFT size, rate, averaging, and max-hold
• Browser Audio Playback — Demodulated PCM audio streamed over WebSocket, played with the Web Audio API
• 14 Demodulation Modes — OFF, Raw I/Q, AM, AM-Sync, LSB, USB, CW-L, CW-U, NFM, WFM, WFM-Stereo, WFM-OIRT, ADS-B, LRPT (gqrx-compatible + satellite)
• ADS-B Reception — Decode Mode S Extended Squitter (1090 MHz) messages: Manchester decoding, CRC verification with single-bit error correction, CPR (Compact Position Reporting) position decoding, aircraft tracking with callsign/altitude/speed/heading/vertical-rate extraction
• Meteor-M LRPT Weather Satellite — Full digital decode of LRPT (Low Rate Picture Transmission) imagery from Meteor-M N2-3/N2-4 (137 MHz, the successor to NOAA APT which ended with the POES decommissioning): QPSK 72k demodulation (RRC matched filter, Costas loop, Gardner timing recovery, FFT-based carrier acquisition), soft-decision Viterbi (K=7, r=1/2), CCSDS deframing with derandomization, Reed-Solomon (255,223)×4 error correction, CCSDS space packet reassembly, MSU-MR JPEG decoding (per-channel APID 64-69), live constellation diagram, real-time segment-by-segment rendering, per-channel PNG export
• Live Aircraft Map — Leaflet-based map showing nearby aircraft positions with locale-aware tile layers (OpenStreetMap / AutoNavi); auto-requests browser geolocation for receiver position
• Full DSP Chain — DDC, FIR bandpass filtering, AGC with presets, anti-aliased audio resampling
• gqrx-compatible Parameters — AGC presets (Off/Slow/Medium/Fast), filter presets (Wide/Normal/Narrow), filter shapes (Soft/Normal/Sharp), CW offset, WFM de-emphasis
• Internationalization — English / Chinese UI with locale toggle
• State Recovery — All settings are synced from the backend on page refresh; audio playback survives tab switches

Architecture

RTL-SDR → IQ Stream → ┌→ FFT (spectrum/waterfall) → WebSocket → Canvas
                      └→ DDC → Bandpass Filter → Demod → AGC → Resampler → WebSocket → Web Audio API
                      └→ ADS-B Decoder → Aircraft Tracker → WebSocket → Leaflet Map
                      └→ LRPT Decoder (QPSK → Viterbi → RS → JPEG) → WebSocket → Canvas Image

DSP Signal Chain

Stage	File	Description
Source	internal/sdr/source.go	RTL-SDR async read, 8-bit IQ → complex128
Device Abstraction	internal/sdr/device.go	SDRDevice interface, DeviceManager for enumeration & hot-swap
FFT	internal/sdr/fft.go	Custom radix-2 Cooley-Tukey FFT, Hann window, max-hold with decay
DDC	internal/sdr/ddc.go	Digital down-converter (NCO + FIR low-pass + decimation)
Filter	internal/sdr/filter.go	Windowed-sinc FIR design (low-pass / band-pass / complex band-pass)
Demodulator	internal/demod/	FM, WFM (mono/stereo/OIRT), AM, AM-Sync (PLL), SSB
AGC	internal/sdr/agc.go	AGC with hang, gqrx-matched presets
Resampler	internal/sdr/resampler.go	Anti-aliased FIR + linear interpolation to 48 kHz
Receiver	internal/sdr/receiver.go	Top-level orchestration, per-client pub/sub for FFT & audio, source hot-swap
ADS-B Decoder	internal/adsb/decoder.go	IQ → preamble detection → Manchester decoding → CRC verification
ADS-B Messages	internal/adsb/message.go	Callsign, altitude, airborne position, velocity extraction
ADS-B CPR	internal/adsb/cpr.go	Compact Position Reporting (global + relative) decoding
ADS-B CRC	internal/adsb/crc.go	Mode S 24-bit CRC with single-bit error correction
ADS-B Tracker	internal/adsb/tracker.go	Multi-aircraft tracking, ICAO-based state merging, CPR caching
LRPT Demodulator	internal/lrpt/demod.go	QPSK 72k: AGC, Costas loop, RRC matched filter, Gardner timing, FFT carrier acquisition
LRPT FEC	internal/lrpt/viterbi.go / rs.go	Soft-decision Viterbi (K=7, r=1/2, CCSDS 0171/0133); Reed-Solomon (255,223) ×4 interleave
LRPT Deframer	internal/lrpt/deframer.go	ASM correlation with 8-fold QPSK ambiguity resolution, PN derandomization
LRPT Packets	internal/lrpt/packet.go	VCDU → CCSDS space packet reassembly, MSU-MR segment extraction
LRPT JPEG	internal/lrpt/jpeg.go	MSU-MR JPEG: Annex K Huffman tables, quality-scaled dequantization, IDCT

Build

Prerequisites

# RTL-SDR library and headers
sudo apt install librtlsdr-dev libusb-1.0-0-dev

# Go 1.22+ and Node.js 18+

Makefile (recommended)

make build    # Build complete single binary (frontend + backend) → bin/
make run      # Build and run
make web      # Build frontend only
make dev      # Start Vite dev server (proxies API to backend)
make clean    # Clean build artifacts

Manual Build

cd web && npm install && npm run build    # Frontend → web/dist/
go build -trimpath -ldflags="-s -w" -o bin/goether-sdr .

Prerequisites:

# Install QEMU binfmt handlers (one-time, for cross-architecture emulation)
docker run --privileged --rm tonistiigi/binfmt --install all

# Create a Docker Buildx builder that supports all platforms
docker buildx create --name mybuilder --use --driver docker-container
docker buildx inspect --bootstrap

Build commands:

make build-amd64    # → bin/goether-sdr-linux-amd64  (x86_64)
make build-arm64    # → bin/goether-sdr-linux-arm64  (aarch64)
make build-arm      # → bin/goether-sdr-linux-arm    (armv7)
make build-all      # All three architectures

make dist           # Build all + package into tarballs in dist/

Usage

# Defaults: device 0, 1.8 MHz sample rate, 102.8 MHz, port 8080
./goether-sdr

# Custom parameters
./goether-sdr -device 0 -freq 144500000 -samplerate 2400000 -port 8080 -ppm 1

# Manual gain
./goether-sdr -autogain=false -gain 248  # 24.8 dB (gqrx default)

Open https://localhost:8080 in your browser.

The server uses HTTPS by default (required for browser geolocation). A self-signed certificate (cert.pem / key.pem) is auto-generated in the binary's directory on first run. Accept the browser's security warning to proceed. Use -tls=false to disable.

CLI Flags

Flag	Default	Description
-device	0	RTL-SDR device index
-samplerate	1800000	Sample rate in Hz (gqrx default: 1.8 MHz)
-freq	102800000	Center frequency in Hz (default: 102.8 MHz)
-port	8080	HTTP server port
-tls	true	Use HTTPS (auto-generates self-signed cert if needed)
-autogain	true	Enable SDR auto gain
-gain	248	Manual gain in 0.1 dB (248 = 24.8 dB, gqrx default)
-ppm	0	Frequency correction in ppm

API Reference

REST

Method	Endpoint	Body	Description
GET	/api/device	—	Active device info
GET	/api/devices	—	List available devices
POST	/api/device/select	{"id":"..."}	Select / open a device
GET	/api/status	—	Receiver status & config
GET	/api/demods	—	Available demodulator list
POST	/api/frequency	{"frequency":100000000}	Set center frequency
POST	/api/demod	{"demod":"NFM"}	Set demodulator
POST	/api/filter	{"low":-5000,"high":5000}	Set filter cutoffs
POST	/api/filter-offset	{"offset":0}	Set filter offset
POST	/api/filter-shape	{"shape":"normal"}	Set filter shape (soft/normal/sharp)
POST	/api/filter-preset	{"preset":"normal"}	Set filter preset (wide/normal/narrow)
POST	/api/squelch	{"level":-80}	Set squelch level (dBFS)
POST	/api/agc	{"enabled":true}	Enable/disable AGC
POST	/api/agc-preset	{"preset":"medium"}	Set AGC preset (off/slow/medium/fast)
POST	/api/gain	{"gain":248}	Set manual gain (0.1 dB)
POST	/api/auto-gain	{"auto":true}	Enable/disable SDR auto gain
POST	/api/freq-correction	{"ppm":1}	Set frequency correction
POST	/api/cw-offset	{"offset":700}	Set CW/BFO offset (Hz)
POST	/api/spectrum-avg	{"avg":0.3}	Set FFT averaging factor
POST	/api/fft-size	{"size":8192}	Set FFT size
POST	/api/fft-rate	{"rate":25}	Set FFT refresh rate (fps)
POST	/api/fft-max-hold	{"enabled":true}	Enable/disable max-hold
POST	/api/receiver-position	{"latitude":39.9,"longitude":116.4}	Set receiver position (for ADS-B CPR)
GET	/api/aircraft	—	Current tracked aircraft list
GET	/api/lrpt/satellites	—	List of Meteor-M LRPT satellites
GET	/api/lrpt-stats	—	LRPT decoder statistics + constellation
POST	/api/lrpt-reset	{}	Reset LRPT decoder state

WebSocket

Endpoint	Format	Description
/api/ws/fft	Binary: 4-byte size → float32[] frames	FFT spectrum data
/api/ws/audio	Binary: 1-byte channels + 4-byte count + int16[] samples	Audio PCM
/api/ws/status	JSON	Receiver status updates (500 ms interval)
/api/ws/aircraft	JSON: Aircraft[]	ADS-B aircraft positions (broadcast every 10 blocks)
/api/ws/lrpt	Binary: u16 apid + u32 strip + u8 mcuIndex + u8 rsvd + 896-byte pixels (112×8)	Meteor-M LRPT image segments

License

This project is licensed under the GNU General Public License v2.0.

GoEther-SDR — A Go-based SDR receiver with web UI
Copyright (C) 2024  GoEther-SDR contributors

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

See the LICENSE file for the full text of the GPLv2.