ADS-B / 978 Integration

WarDragon can ingest aircraft tracks from a local readsb instance and forward them as CoT to TAK/ATAK and as JSON to MQTT alongside drone detections. This is useful for situational awareness (where are the commercial / GA aircraft relative to the drones we're tracking?) and is the same pipeline that powers the aircraft layer in WarDragonAnalytics.

Status: Experimental. Setup is a multi-step process and requires SDR planning — see SDR Considerations before starting.

Overview

Antenna → SDR (1090 / 978 MHz) → readsb → HTTP API → DragonSync → CoT / MQTT

DragonSync polls the local readsb HTTP API and, for each aircraft with a valid position, builds a CoT message with position, altitude, speed, track, and a <remarks> block containing hex code, callsign, squawk, registration, and category. Accuracy fields (CE/LE) are derived from NACp/NACv when readsb provides them.

SDR Considerations

The base WarDragon kits include a single dedicated SDR — the DragonSDR — and that radio is reserved for DJI DroneID detection. ADS-B reception needs its own RF front-end, so you have two practical paths:

Setup	Trade-off
Repurpose the DragonSDR for ADS-B temporarily	You lose DJI DroneID detection while it's tuned to 1090/978 MHz. Useful for demos, lab work, or environments where DJI detection isn't required.
Add a dedicated ADS-B SDR (recommended)	Plug an additional USB SDR (RTL-SDR is the common choice for 1090 / 978 MHz) into the WarDragon. DJI detection on the DragonSDR continues uninterrupted.

Note for WarDragon Elite kits: the BladeRF is used by DragonSig for FPV / RFD900 / mLRS / ELRS missions — so even on Elite, ADS-B requires a separate USB SDR (an RTL-SDR is the common choice).

A purpose-built ADS-B antenna helps a lot. The stock dual-band antennas will pick up the strongest 1090 MHz returns but range is limited.

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Setup

1. Start readsb

RTL-SDR (Recommended)

The simplest configuration — plug an RTL-SDR into a free USB port and run:

sudo readsb \
  --device-type rtlsdr \
  --freq=1090000000 \
  --no-interactive \
  --write-json=/run/readsb \
  --write-json-every=1 \
  --json-location-accuracy=2 \
  --net-bind-address=0.0.0.0 \
  --net-api-port=8080

DragonSDR / Pluto-Compatible (via SoapySDR)

If you're repurposing the DragonSDR for ADS-B (and accepting the loss of DJI detection while it's tuned to 1090 MHz):

sudo readsb \
  --device-type soapysdr \
  --soapy-device="driver=plutosdr" \
  --freq=1090000000 \
  --no-interactive \
  --write-json=/run/readsb \
  --write-json-every=1 \
  --json-location-accuracy=2 \
  --net-bind-address=0.0.0.0 \
  --net-api-port=8080 \
  --soapy-enable-agc \
  --sdr-buffer-size=128

Before doing this, stop the dji-receiver service so it doesn't conflict for the DragonSDR:

sudo systemctl stop dji-receiver

Key Options

Option	Description
--freq=1090000000	1090 MHz for standard ADS-B (worldwide)
--freq=978000000	978 MHz for UAT (US only)
--net-api-port=8080	HTTP API port DragonSync polls
--device-type	soapysdr, rtlsdr, etc.
--soapy-device	SoapySDR device string
--write-json=/run/readsb	Where readsb writes its JSON state

2. Verify readsb

Test the HTTP API:

curl -s http://127.0.0.1:8080/?all_with_pos | jq '.aircraft | length'

You should see a count of aircraft with positions. 0 or an error means readsb isn't receiving data — check the antenna and SDR connection.

3. Configure DragonSync

Add to /home/dragon/DragonSync/config.ini:

[SETTINGS]

# ADS-B / UAT aircraft ingestion
adsb_enabled = true
adsb_json_url = http://127.0.0.1:8080/?all_with_pos

# How frequently to fetch from readsb (seconds)
adsb_rate_limit = 3.0

# How long after last seen before CoT goes stale (seconds)
adsb_cot_stale = 15

# Internal track cache time-to-live (seconds)
adsb_cache_ttl = 120

# UID prefix for ADS-B CoT events
adsb_uid_prefix = adsb-

# Optional altitude gates (feet). 0 = disabled.
adsb_min_alt = 0
adsb_max_alt = 0

Then restart DragonSync:

sudo systemctl restart dragonsync

Altitude Filtering

# Only show aircraft below 10,000 feet
adsb_max_alt = 10000

# Only show aircraft above 1,000 feet (ignore ground traffic)
adsb_min_alt = 1000

# Both: 1,000 to 10,000 feet
adsb_min_alt = 1000
adsb_max_alt = 10000

Set either to 0 to disable that side of the filter.

---

How It Works

1. DragonSync polls adsb_json_url at the cadence set by adsb_rate_limit
2. Expects readsb-style JSON with an aircraft array
3. For each aircraft with a valid position:
   • Builds a CoT message with position, altitude, speed, track
   • Includes hex code, callsign, squawk, registration, category in remarks
   • Derives accuracy (CE/LE) from NACp/NACv when available
4. Outputs CoT via the configured TAK server or multicast — same pipeline as drone detections

CoT Mapping

readsb Field	CoT Element
hex	UID suffix (with adsb_uid_prefix)
lat, lon	Point position
alt_geom or alt_baro	HAE (converted to meters)
gs	Speed (converted to m/s)
track	Course
flight	Callsign in remarks
squawk	Squawk in remarks
category	Aircraft category in remarks
nac_p, nac_v	CE/LE accuracy

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MQTT Output

To publish aircraft data to MQTT, enable aircraft publishing in config.ini:

mqtt_enabled = true
mqtt_aircraft_enabled = true
mqtt_aircraft_topic = wardragon/aircraft

Aircraft tracks publish to the configured topic (default: wardragon/aircraft):

{
  "icao": "A12345",
  "callsign": "UAL123",
  "registration": "N12345",
  "lat": 39.1234,
  "lon": -77.5678,
  "alt": 35000,
  "speed": 450,
  "track": 270,
  "squawk": "1200",
  "category": "A3",
  "on_ground": false,
  "rssi": -8.5,
  "track_type": "aircraft"
}

For Home Assistant integration and field-by-field schema details see MQTT & Home Assistant.

Signal Strength (RSSI)

The rssi field on aircraft tracks contains signal strength from readsb, measured in dBFS (decibels relative to full scale), not dBm.

Value	Meaning
0 dBFS	Maximum signal (ADC saturation)
-10 dBFS	Very strong signal
-20 dBFS	Good signal
-30 dBFS	Weak signal

• dBFS is relative to the SDR's ADC, not absolute power
• Values depend on SDR gain settings
• For multi-kit triangulation, all kits should use similar gain settings
• rssi may be null if readsb doesn't provide it (older versions or certain configurations)

---

Running readsb as a Service

For persistent operation, run readsb under systemd. Create /etc/systemd/system/readsb.service:

[Unit]
Description=readsb ADS-B receiver
After=network.target

[Service]
ExecStart=/usr/bin/readsb \
  --device-type rtlsdr \
  --freq=1090000000 \
  --no-interactive \
  --write-json=/run/readsb \
  --write-json-every=1 \
  --json-location-accuracy=2 \
  --net-bind-address=0.0.0.0 \
  --net-api-port=8080
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target

Enable and start:

sudo systemctl daemon-reload
sudo systemctl enable readsb
sudo systemctl start readsb
sudo systemctl status readsb

Adjust ExecStart for your SDR — replace the --device-type and --soapy-device arguments as needed.

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Troubleshooting

Issue	Diagnosis	Resolution
No aircraft in ATAK	curl http://127.0.0.1:8080/?all_with_pos returns empty / error	readsb isn't receiving — check SDR, antenna, line of sight
readsb won't start	Permission denied on SDR device	Add udev rules for RTL-SDR; verify user can access /dev/bus/usb/*
SoapySDR device not found	SoapySDRUtil --find shows no devices	Reinstall SoapySDR modules for your SDR vendor
Only some aircraft appear	Endpoint URL wrong	Use /?all_with_pos (not just /?) — many endpoints require positions
High CPU on DragonSync	Polling too often	Increase adsb_rate_limit (in seconds between polls)
Conflicts with DJI detection	DragonSDR repurposed	Stop dji-receiver while DragonSDR is on 1090 MHz; restart it when reverting

Common readsb Issues

Permission denied on SDR:

# Add udev rules for RTL-SDR
sudo cp rtl-sdr.rules /etc/udev/rules.d/
sudo udevadm control --reload-rules
sudo udevadm trigger

SoapySDR device discovery:

SoapySDRUtil --find
SoapySDRUtil --probe="driver=plutosdr"

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Frequency Reference

Frequency	Service	Region
1090 MHz	ADS-B (Mode S)	Worldwide
978 MHz	UAT (ADS-B)	United States only, below 18,000 ft

International flights and high-altitude traffic use 1090 MHz exclusively. 978 MHz UAT is a US-only General Aviation band — ignore it outside the US.

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Related Documentation

• DragonSync Configuration — full adsb_* parameter reference
• TAK Integration — where the CoT goes
• MQTT & Home Assistant — aircraft topic / field reference
• WarDragonAnalytics — visualizes aircraft alongside drones in the multi-kit dashboard
• Upstream: DragonSync ADS-B Setup
• Upstream: readsb