Dual-Band ADS-B & UAT SDR Aviation Telemetry Pipeline

Demodulating 1090MHz Mode S & 978MHz UAT with RTL-SDR, Real-Time WebGL Radar & Multi-Feed Multiplexing

Architectural Overview

This station captures and demodulates real-time commercial and general aviation transponder broadcasts across two independent RF bands (1090 MHz Mode S/ADS-B and 978 MHz UAT). Powered by containerized Software Defined Radio (SDR) demodulators (readsb-1090, dump978), the system renders a local WebGL/Leaflet spatial radar interface and multiplexes normalized Beast/BaseStation binary streams to global flight-tracking aggregators.

flowchart TD
    subgraph Antennas["1. RF Physical Antenna Layer"]
        Ant1090["📡 1090 MHz Tuned Collinear Antenna\n(Commercial Airliners / Mode S)"]
        Ant978["📡 978 MHz Ground-Plane Antenna\n(General Aviation / UAT & FIS-B)"]
    end

    subgraph SDRHardware["2. SDR Ingestion & Demodulation"]
        SDR1["📻 RTL-SDR v4 Dongle\n(/dev/bus/usb/001/004)"]
        SDR2["📻 RTL-SDR v4 Dongle\n(/dev/bus/usb/001/005)"]
        Ant1090 --> SDR1
        Ant978 --> SDR2
    end

    subgraph DemodEngine["3. Demodulation & Feed Normalization"]
        ReadSB["⚡ readsb-1090\n(Beast Binary Stream :30005)"]
        Dump978["⚡ dump978\n(UAT Raw Stream :30978)"]
        SDR1 --> ReadSB
        SDR2 --> Dump978
    end

    subgraph Presentation["4. Visualization & Storage"]
        Tar1090["🗺️ tar1090 WebGL Radar Interface\n(Port 8078 / Real-Time Trails)"]
        ReadSB & Dump978 --> Tar1090
    end

    subgraph Feeders["5. Multi-Target Ingestion Multiplexer"]
        ADSBEx["🌐 ADS-B Exchange Feeder"]
        PiAware["🌐 FlightAware PiAware (MLAT)"]
        RadarBox["🌐 AirNav RadarBox"]
        FR24["🌐 FlightRadar24 Feed"]
        
        ReadSB & Dump978 --> ADSBEx & PiAware & RadarBox & FR24
    end

---

1. Dual-Band RF Signal Processing

Commercial and general aviation aircraft broadcast kinematic flight telemetry over two distinct radio frequencies:

1. 1090 MHz Extended Squitter (Mode S / ADS-B):
   • High-altitude commercial airliners broadcasting 112-bit pulses containing ICAO 24-bit transponder addresses, latitude/longitude (Compact Position Reporting), pressure altitude, ground speed, and heading.
   • Demodulated by readsb using customized sample rates and automatic gain calibration (--gain=-10) to prevent low-noise amplifier saturation from nearby flight corridors.
2. 978 MHz Universal Access Transceiver (UAT):
   • Utilized by general aviation, experimental aircraft, and low-altitude helicopters. Also carries Flight Information Services-Broadcast (FIS-B) weather and Traffic Information Services-Broadcast (TIS-B).
   • Demodulated by dump978, which decodes raw I/Q samples directly into structured Beast JSON frames.

---

2. Containerized Feed Multiplexing Architecture

The architecture decouples RF demodulation from upstream feeder clients using an in-memory TCP streaming pipeline:

# /mnt/sharedroot/compose/llmadmin01/adsb-stack/docker-compose.yml
services:
  readsb-1090:
    image: mikenye/readsb:latest
    devices:
      - /dev/bus/usb:/dev/bus/usb
    ports:
      - "8087:8080"   # Diagnostics & metrics
      - "30002:30002" # Raw Beast output
      - "30003:30003" # BaseStation CSV format
      - "30005:30005" # Beast binary feed
    command:
      - --net
      - --net-bo-port=30005
      - --net-sbs-port=30003
      - --device-type=rtlsdr
      - --device=1090
      - --gain=-10
      - --write-json=/run/readsb
    volumes:
      - readsb-pb-data:/run/readsb
 
  tar1090:
    image: mikenye/tar1090:latest
    environment:
      - READSB_HOST=readsb-1090
      - READSB_PORT=30005
      - UAT_HOST=dump978
      - UAT_PORT=30978
    ports:
      - "8078:80"

Decoupled Upstream Feeders:

Feeder containers connect internally to readsb-1090:30005 and dump978:30978, eliminating duplicate radio tuner locks while simultaneously transmitting verified telemetry to:

• ADS-B Exchange: Unfiltered, non-censored aviation telemetry with MLAT (Multilateration) support.
• FlightAware PiAware: Feeds global commercial networks with synchronized UTC timestamps.
• FlightRadar24 & AirNav RadarBox: Global crowdsourced air traffic networks.

---

3. High-Performance Spatial Radar UI (tar1090)

The station exposes a zero-latency WebGL radar interface on local port 8078:

• Aircraft Trajectory History: Stores recent aircraft position history in memory, rendering color-coded altitude gradients, speed vectors, and climbing/descending indicators.
• Multilateration (MLAT) Tracking: Identifies non-ADS-B Mode A/C aircraft by triangulating radio arrival time differences across collaborative receiver nodes.
• Range Polar Plots: Automatically generates 360-degree RF reception range rings, validating antenna line-of-sight and terrain obstruction boundaries up to 250+ nautical miles.

---

🔗 Related Architecture & Knowledge Graph

• Production Systems: Validated in SDR and RF Exploration, Unified Fleet Observability Alloy.
• Governance & Compliance: Governed by Data Classification Policy.
• Technical Articles: Deep dive in Bare Metal Diagnostics Lessons.
• Applied Research: Investigated in index.
• Master Credentials: Review core competencies on Curriculum Vitae & Master Resume.
• Digital Garden Hub: Return to the main Digital Garden Index.