ADS-B stands for Automatic Dependent Surveillance-Broadcast. It’s the modern way aircraft communicate their position to air traffic control and to each other.
Every ADS-B equipped aircraft continuously broadcasts: - Position (from GPS) - Altitude - Speed - Aircraft ID
This happens automatically, about once per second. No radar needed — the aircraft tells everyone where it is.
In the US, ADS-B operates on two frequencies:
| Frequency | Name | What It Does |
|---|---|---|
| 1090 MHz | Mode S Extended Squitter | Aircraft-to-aircraft. Works everywhere, even over oceans. This is what airliners and most GA aircraft broadcast on. |
| 978 MHz | UAT (Universal Access Transceiver) | US only, below 18,000 feet. Ground towers rebroadcast traffic AND send free weather (FIS-B). |
Stratux receives both frequencies: - 1090 MHz → See other aircraft directly (works on the ground) - 978 MHz → Get traffic AND weather from FAA ground towers (needs altitude/line-of-sight)
Stratux is an ADS-B In receiver. It doesn’t broadcast anything — it just listens.
The FAA’s ground-based ADS-B network (978 MHz) broadcasts weather products called FIS-B: - NEXRAD radar - METARs - TAFs - TFRs - NOTAMs - Winds aloft
This is completely free — no subscription needed. Stratux receives it and sends it to your EFB app.
The 978 MHz ground towers are line-of-sight. If you’re on the ground, terrain and buildings block the signal. Once you’re about 1,000 feet AGL, you’ll start seeing weather data flow in.
Still have questions? Check out FAA’s ADS-B FAQ or ask us!