SDR Setup Guide

Complete guide for setting up Software Defined Radio (SDR) receivers with EAS Station

Quick Navigation

5-Minute Quick Start - Get running fast with Docker
Hardware Guide - Choosing the right SDR
Setup Flowchart - Visual overview
Web UI Setup - Easiest configuration method
Troubleshooting - Fix common issues

Visual Setup Guide

For a complete visual overview of the SDR setup process:

View full-size diagram

Quick Start

For Docker users - 5 minutes to working SDR

What's Included

SoapySDR, RTL-SDR, and Airspy drivers are pre-installed in the Docker image:

✅ SoapySDR core libraries
✅ RTL-SDR drivers (default)
✅ Airspy drivers (default)
✅ USB device passthrough (pre-configured)
✅ No .env configuration needed

Setup Steps

Plug in your SDR device

   # Verify device is detected on host
   lsusb | grep -i rtl  # For RTL-SDR
   lsusb | grep -i airspy  # For Airspy

Start the containers

   sudo docker compose up -d

Verify SDR detection

# Check SoapySDR can see the device sudo docker compose exec app SoapySDRUtil --find

# Run diagnostic script sudo docker compose exec app python scripts/sdr_diagnostics.py

Configure in Web UI

Open http://localhost (or your server IP)
Navigate to Settings → Radio Receivers
Click Discover Devices
Click Add This Device on your SDR
Apply a preset (NOAA Weather Radio recommended)
Save and enable

Done! Your SDR should now show "Locked" status.

> Non-root users: Add yourself to the docker group to avoid sudo: sudo usermod -aG docker $USER (log out and back in)

Hardware Requirements

Supported SDR Devices

Device	Frequency Range	Sample Rate	Cost	Best For
RTL-SDR V3	24 MHz - 1.7 GHz	Up to 2.4 MSPS	$20-40	NOAA Weather Radio, budget builds
Airspy Mini	24 MHz - 1.7 GHz	Up to 6 MSPS	$100+	Better sensitivity, professional use
Airspy R2	24 MHz - 1.7 GHz	Up to 10 MSPS	$200+	Maximum performance

Recommended starter: RTL-SDR Blog V3 ($30) with bias-tee for powered antennas

Antenna Requirements

For NOAA Weather Radio (162 MHz):

Type	Performance	Cost	Notes
Telescoping whip	Good for testing	$5-10	Included with most RTL-SDR kits
1/4 wave ground plane	Excellent	$20-40	~19 inches, outdoor mount
Commercial scanner	Excellent	$30-80	VHF optimized, weather-resistant

Signal improvement tips:

Place antenna near window or outdoors
Higher is better (roof/attic mounting)
Keep away from computers and USB hubs (RF interference)
Use quality coaxial cable (low-loss RG-6 or LMR-400)

Software Installation

Docker Deployment (Recommended)

No installation needed! SoapySDR and all drivers are built into the Docker image.

The image includes:

SoapySDR core libraries and Python bindings
RTL-SDR and Airspy drivers (via SOAPYSDR_DRIVERS build arg)
USB device support (libusb)
NumPy for signal processing

USB device access is pre-configured in docker-compose.yml:

devices:

/dev/bus/usb:/dev/bus/usb

privileged: true

Optional: Customize driver installation

To reduce build time, install only the drivers you need in .env:

Only RTL-SDR (faster builds)
SOAPYSDR_DRIVERS=rtlsdr
Both RTL-SDR and Airspy (default)
SOAPYSDR_DRIVERS=rtlsdr,airspy

Host Installation (Without Docker)

If running EAS Station directly on the host:

Ubuntu/Debian
sudo apt update
sudo apt install python3-soapysdr soapysdr-module-rtlsdr soapysdr-module-airspy python3-numpyVerify installation
SoapySDRUtil --info
SoapySDRUtil --find

Docker USB Passthrough

Verify USB Access

1. Check if SDR is detected on host
lsusb | grep -i rtl  # Or grep -i airspyExpected output:
Bus 001 Device 005: ID 0bda:2838 Realtek Semiconductor Corp. RTL2838 DVB-T
2. Verify container can access USB devices
sudo docker compose exec app ls -la /dev/bus/usb3. Test SoapySDR inside container
sudo docker compose exec app SoapySDRUtil --find

Troubleshooting USB Issues

Problem: No devices found

Kernel driver conflict (RTL-SDR only)

The DVB-T TV tuner driver blocks RTL-SDR access:

# On host, create /etc/modprobe.d/blacklist-rtl.conf: sudo tee /etc/modprobe.d/blacklist-rtl.conf <<EOF blacklist dvbusbrtl28xxu blacklist rtl2832 blacklist rtl2830 EOF # Unload the module sudo modprobe -r dvbusbrtl28xxu

# Reboot to make permanent sudo reboot

Container needs restart

   sudo docker compose restart

USB device path changed

Using /dev/bus/usb:/dev/bus/usb (already configured) handles this automatically.

Web UI Configuration

Easiest way to configure SDRs

Step-by-Step Setup

flowchart TD A[Navigate to Settings → Radio Receivers] --> B[Click 'Run Diagnostics'] B --> C{Diagnostics Pass?} C -->|No| D[See Troubleshooting] C -->|Yes| E[Click 'Discover Devices'] E --> F[Click 'Add This Device'] F --> G[Choose Preset] G --> H[NOAA Weather Radio RTL-SDR<br/>or<br/>NOAA Weather Radio Airspy] H --> I[Update frequency for your area] I --> J[Save Receiver] J --> K{Status = Locked?} K -->|No| L[Check antenna/frequency] K -->|Yes| M[Success! Monitor alerts]

1. Access Radio Settings

Log into EAS Station web interface
Navigate to Settings → Radio Receivers

2. Run Diagnostics

Click Run Diagnostics button
Verify all checks pass:

✓ SoapySDR is installed
✓ NumPy is installed
✓ RTL-SDR or Airspy driver available
✓ At least 1 device detected

If diagnostics fail → Troubleshooting

3. Discover and Add Device

Click Discover Devices
Review detected SDRs
Click Add This Device on your SDR
Form pre-fills with device info

4. Apply Preset (Recommended)

Click Use Preset
Choose:

NOAA Weather Radio (RTL-SDR) - For RTL-SDR dongles
NOAA Weather Radio (Airspy) - For Airspy receivers

Click Use This Preset

5. Set Your Local Frequency

Find your nearest NOAA Weather Radio station: https://www.weather.gov/nwr/station_listing

NOAA Frequencies:

Channel	Frequency
WX1	162.400 MHz
WX2	162.425 MHz
WX3	162.450 MHz
WX4	162.475 MHz
WX5	162.500 MHz
WX6	162.525 MHz
WX7	162.550 MHz

Convert to Hz: Multiply MHz × 1,000,000 Example: 162.550 MHz = 162550000 Hz

6. Enable and Monitor

Check Enabled and Auto-start
Click Save Receiver
Wait for Locked status (green badge)
Check signal strength (should be > 0.1 dBFS for good reception)

Manual Configuration

Configuration Fields

Field	RTL-SDR Example	Airspy Example	Description
Display Name	`Main NOAA Receiver`	`Backup NOAA`	Friendly name
Identifier	`rtlsdrmain`	`airspybackup`	Unique ID (no spaces)
Driver	`rtlsdr`	`airspy`	SoapySDR driver name
Frequency (Hz)	`162550000`	`162550000`	162.55 MHz
Sample Rate	`2400000`	`2500000`	2.4/2.5 MSPS
Gain (dB)	`49.6`	`21`	See gain guide below
Channel	`0` or empty	`0` or empty	Multi-channel SDRs only
Enabled	✓	✓	Start on boot
Auto-start	✓	✓	Restart if crashes

Gain Settings Guide

RTL-SDR:

Range: 0-50 dB
Start with: 49.6 dB (maximum sensitivity)
Adjust down if signal is too strong (> 1.0 dBFS)

Airspy:

Range: 0-21 dB (linearity mode) or 0-15 dB (sensitivity mode)
Start with: 21 dB
Airspy has automatic gain control (AGC) option

Too much gain = Overload, distortion Too little gain = Weak signal, poor decoding

Testing and Verification

Using Diagnostic Tools

Full diagnostic check
sudo docker compose exec app python scripts/sdr_diagnostics.pyEnumerate all devices
sudo docker compose exec app python scripts/sdr_diagnostics.py --enumerateCheck driver capabilities
sudo docker compose exec app python scripts/sdr_diagnostics.py --capabilities rtlsdrTest sample capture (5 seconds at 162.55 MHz)
sudo docker compose exec app python scripts/sdr_diagnostics.py \
  --test-capture --driver rtlsdr --frequency 162550000 --duration 5Show available presets
sudo docker compose exec app python scripts/sdr_diagnostics.py --presets

Web UI Status Check

Navigate to Settings → Radio Receivers
Check Receiver Status panel:

Locked count > 0
Green "Locked" badges in receiver table
Signal strength displayed (dBFS)

Expected Signal Levels

Signal Strength	Status	Notes
0.1 - 1.0 dBFS	Excellent	Strong, clear lock
0.01 - 0.1 dBFS	Fair	Works but may have dropouts
< 0.01 dBFS	Poor	Unlikely to decode properly
> 1.0 dBFS	Overload	Reduce gain to prevent distortion

Troubleshooting

"No SDR Devices Found"

Possible causes and solutions:

SDR not plugged in

Check USB connection
Try different USB port (USB 2.0 often better than USB 3.0)
Verify with lsusb on host

Kernel driver conflict (RTL-SDR)

See Docker USB Passthrough section
Blacklist DVB-T drivers

Container needs rebuild

   sudo docker compose build app
   sudo docker compose up -d

Restart containers after plugging in device

   sudo docker compose restart

"Receiver shows 'No lock' status"

Wrong frequency

Verify correct NOAA station: https://www.weather.gov/nwr/station_listing
Double-check frequency entered in Hz (not MHz)

Weak signal

Improve antenna (see Hardware Requirements)
Move antenna to window or outdoors
Increase gain (but watch for overload)

No antenna connected

Ensure antenna is firmly attached to SMA connector

Interference

Move SDR away from computers, power supplies
Use shielded USB cable
Try powered USB hub for better power delivery

"Signal strength is 0 or very low"

Check antenna connection - Firm SMA connection
Verify frequency - Matches local NOAA station
Increase gain - Try 49.6 dB for RTL-SDR, 21 dB for Airspy
Test with FM radio - Tune to 88-108 MHz to verify hardware works

"SoapySDR not installed" (Shouldn't happen with Docker)

For Docker:

Rebuild image
sudo docker compose build app
sudo docker compose up -d

For host installation:

sudo apt install python3-soapysdr soapysdr-module-rtlsdr python3-numpy

"Permission denied" errors

Already configured in docker-compose.yml:

devices:

/dev/bus/usb:/dev/bus/usb

cap_add:

SYS_RAWIO

If still having issues, add user to plugdev group:

sudo usermod -aG plugdev $USER
Log out and back in

Advanced Topics

Multiple SDR Receivers

Run multiple SDRs simultaneously:

Use cases:

Monitor multiple NOAA frequencies
Redundancy (backup receivers)
Different signal types (weather + FM broadcast)

Configuration:

All SDRs will appear in Discover Devices
Add each with unique names
Configure different frequencies
Each runs independently

Example setup:

Receiver 1: rtlsdr_wx → 162.550 MHz (NOAA)
Receiver 2: rtlsdr_fm → 95500000 Hz (FM broadcast)
Receiver 3: airspy_backup → 162.550 MHz (backup)

Capture Modes

Configure in .env:

IQ mode: Complex 32-bit I/Q samples (for offline analysis)
RADIOCAPTUREMODE=iqPCM mode: Float32 interleaved I/Q (for direct audio decoders)
RADIOCAPTUREMODE=pcm

Capture Duration

Capture 30 seconds when SAME burst detected
RADIOCAPTUREDURATION=30

Signal Analysis Tools

Analyze captured IQ files with:

GNU Radio - Signal processing and demodulation
inspectrum - Visual spectrum analyzer
Custom Python - NumPy/SciPy analysis

Performance Optimization

Use USB 3.0 ports for higher sample rates
Avoid USB hubs - Direct motherboard connection
Monitor CPU usage - High sample rates increase CPU load
Check for USB dropouts:

   dmesg | grep -i usb

Security Considerations

For dedicated SDR stations:

/dev/bus/usb:/dev/bus/usb passthrough is safe
No other sensitive USB devices connected

For shared systems:

Consider specific device passthrough
Use udev rules to restrict by vendor/product ID

Getting Help

If you're still having issues:

Check logs: sudo docker compose logs app
Run diagnostics: Web UI or python scripts/sdr_diagnostics.py
GitHub Issues: https://github.com/KR8MER/eas-station/issues

When reporting issues, include:

SDR model and driver (RTL-SDR, Airspy, etc.)
Output of lsusb on host
Output of SoapySDRUtil --find in container
Diagnostic script output
Relevant log excerpts

Additional Resources

SoapySDR Documentation: https://github.com/pothosware/SoapySDR/wiki
RTL-SDR Guide: https://www.rtl-sdr.com/about-rtl-sdr/
Airspy Documentation: https://airspy.com/
NOAA Weather Radio: https://www.weather.gov/nwr/
EAS/SAME Protocol: https://en.wikipedia.org/wiki/SpecificAreaMessage_Encoding

Last Updated: 2025-11-25 Tested With: Docker 24+, RTL-SDR V3, Airspy Mini

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This document is served from docs/hardware/SDR_SETUP.md in the EAS Station installation.