RTL-SDR ADS-B Setup with readsb or dump1090

[Pavel]

Short answer: Connect an RTL-SDR to a 1090 MHz antenna, install one supported decoder, select the correct dongle and tune gain using valid messages rather than waterfall appearance. readsb and dump1090-family decoders both process Mode S/ADS-B; run only one process against a dongle unless data is shared over a network port.

Before you start​

• Use 1090 MHz Mode S and ADS-B as the initial target unless the project specifically requires 978 MHz UAT in a region where it is used.
• Record antenna type and height, coax length, receiver gain, decoder version and a fixed observation window before comparing changes.

Step-by-step method​

1. Step 1: Verify the dongle with rtl_test, give it a unique serial if several receivers are connected and stop any existing feeder service that might already own it.
2. Step 2: Install readsb or a maintained dump1090 package for the operating system. Start local decoding first without external feeders and confirm the process opens the intended RTL device.
3. Step 3: Begin with manual tuner gain around the high-20s to mid-30s dB range, then compare message rate at several gain values. Strong nearby aircraft can overload at maximum gain.
4. Step 4: Open the local aircraft map or decoder statistics, run for at least an hour and verify valid positions. Configure network feeds only after local decoding is stable.

Concrete example​

A clean baseline is one RTL-SDR, roughly 2.4 MSPS as selected by the decoder, a 1090 MHz antenna and 30 dB manual gain. Compare 25, 30, 35 and 40 dB over equal 30-minute periods before choosing a value.

How to judge the result​

The decoder is working when CRC-valid messages, aircraft positions and message rate remain stable without lost-device errors. Keep the local decoder as the single radio owner and let feeders consume its network output.

What to record​

• Compare unique aircraft, maximum range, messages per second and the shape of the polar coverage plot over equal time periods.
• Use at least 24 hours for a meaningful station baseline because traffic direction and density vary throughout the day.
• A higher message rate with fewer distant aircraft can indicate overload, local traffic changes or a different gain compromise rather than a universal improvement.

Common mistakes​

• Changing several hardware, software or RF variables at once, which removes the controlled comparison needed to identify the cause.
• Treating one autoscaled screenshot or one unusually good result as proof without recording the settings and repeating the test.
• Starting readsb and dump1090 simultaneously on the same dongle creates busy-device errors and is not a valid performance comparison.

Final check​

Run the ADS-B station through another comparable observation window. Accept the change only when aircraft, messages and range metrics improve without overload, outages or exposed station credentials.