ADS-B Mode-S

My tracking of nearby ADSB-out aircraft using my local AWACS server.

Automatic dependent surveillance-broadcast - Mode-S

On January 1, 2020, all aircraft in US airspace will be required to have an ADSB-out or UAT capable transponder to transmit their position information to ATC or other aircraft. Since the transmission happens at 1090MHz, is vertically polarized, and is receivable within a line of sight, ground stations can pick up signals from aircraft hundreds of nautical miles away flying at high altitude!

• Wikipedia ADSB
• FAA ADSB

Unscientific deployment observation

Being within the KIAH Mode-C ring, all planes are required to have a squawkable transponder for the primary ATC radar. Unfortunately, most of these planes are invisible without the 1090MHz transponder which allows for a MLAT(multi-lateration) calculation with multiple base stations. Sometimes an ADSB-IN aircraft is flying nearby which will activate a ADSB-R (rebroadcast). The traffic within several miles and within 5000' of the aircraft will be rebroadcast meaning that my AWACS system can now see the ground traffic at major airports as well as random signatures for the remainder of the transponder only flights.

• From 2014, about 1/4th or less had position information. Most international airframes and widebody commercial flights are broadcasting. Also noteworthy early adopters are the cargo carriers who fly heavies to KMEM and KSDF every night in a wave around 22:00.
• Mid 2018, 1/3rd to 1/2 of the 1090MHz responses are ADSB-out. Most of the commercial fleet aircraft are using ADSB-out and the regional airlines are beginning to appear in their CRJ7s and EMB135s. NASA has a T-38 with it and I've even spotted an IL-76 and C-17 using ADSB-out on the same day!

Yesterday's Stats

Country summary

Airframe summary

You only need a few things to get started:

• A RTL-SDR software defined radio
• dump1090 to do the dirty work

My long range setup is using a Raspberry Pi Zero and a ProStickPlus.

To improve the setup:

• Try a Low Noise Amplifier(LNA) and filtered dongle, flightaware - prostick
• You can make some kind of 1090 MHz Antenna, λ=257mm
• Then test the range of the antenna
• Experiment with gain/error correction settings on the SDR
• Move everything off to a Raspberry Pi
• Try to make a shorted quarter-wave (λ/4) stub filter
• Try a sawtooth filter and Low Noise Amplifier(LNA)
• Read some random things I wrote discovering this

ADSB-in

Since it's more expensive to add ADSB-in capability and not required by the FAA many planes don't have this. Fortunately, using almost the same setup as my home AWACS system Stratux can supplement your electronic flight bag. I'm currently using Avare with the external i/o plugin to connect to the homebuilt stratux.

ACARS

Like text messaging for planes. Not 1090MHz and appears to be falling out of style...
acarsdec

Still parsing info from these, seem to be from mostly older planes which don't have adsb-out.

Active Frequencies:

• 129.125MHz
• 129.350MHz
• 130.025MHz
• 130.450MHz
• 131.125MHz
• 131.550MHz
• 131.725MHz
• 136.850MHz

Mode : 2 Label : H1 Id : 5 Nak
Aircraft reg: N595UA Flight id: UA2795
No: F50A
#M2BREQPWI/TS040406,180418/WQ410.370.320:AEX.IAH.WEEED.WAILN.REDNK.RODIO.MARCS.BRAUN.TROOP.CRISS.JATAX.REUBE.HASDO.ALAMO.RW13R.EMBOW/DQ400C705

References and Software

gr-air-modes - ADS-B receiving software.
wikipedia ADS-B
rtl-sdr ads-b article
antirez dump1090
satsignal pi-1090
asd-b.ca
mutability mlat-server
alkissack dump1090
British Airways used this in a pretty neat marketing campaign #lookup.