Currently we're quite often asked if there is a dongle inside the Air!Squitter? No, there isn't!
The ADS-B receiver section of the Air!Squitter is equal to the Mode-S Beast and Radarcape. Both based on a FPGA and highly optimized SDR algorithm. Just we left some options away, like video out and antenna diversity.
A dongle based receiver never reaches the sensitivity of our receiver, and it never provides high precision Multilateration, because it has no GPS timestamps.
Just for the FLARM option we're using a dongle in parallel, and even here not just the cheap R820T2 dongle but the significantly better RTL-SDR dongle.