# SDR Flight Tracking: ADS-B First Pass

Use an RTL-SDR-style receiver to understand public ADS-B aircraft broadcasts: frequency, antenna, receiver, decoder, fields, map display, and the receive-only boundary.

## Outcome
Name the ADS-B frequency, antenna role, receiver role, decoded fields, and map output without confusing receive-only learning with official tracking or transmitting.

## Safe first step
Stay receive-only. Identify the signal type, 1090 MHz frequency, antenna, receiver, decoder, field list, and lawful-use boundary before installing or sharing anything.

## Ladder steps
### 1. Name the signal
ADS-B messages are aircraft broadcasts that a receiver can hear when the antenna, location, and coverage are good enough.

Check: Your note says ADS-B, 1090 MHz, receiver location, and what you expect to decode.

### 2. Trace the receive path
The path is aircraft broadcast, antenna, RTL-SDR, decoder, fields, and map or table.

Check: You can explain which part receives RF, which part samples it, and which part turns samples into readable fields.

### 3. Read the fields
Decoded rows can include callsign, altitude, position, speed, heading, timestamp, and message quality when present.

Check: Your sample field note says what each visible field proves and what it does not prove.

### 4. Write the limits
Reception gaps, stale messages, antenna placement, privacy, local rules, and misuse boundaries belong in the same note as the decoded example.

Check: Your conclusion refuses interference, evasion, stalking, and public-safety misuse.

## Examples
### Map the receive path
```sh
aircraft -> 1090 MHz ADS-B -> antenna -> RTL-SDR -> decoder -> map
```
Expected signal: Each component has a job before the aircraft appears as a dot or row

Caution: Do not treat a map display as official radar authority.

### Read a decoded aircraft row
```sh
callsign + altitude + position + speed + timestamp
```
Expected signal: The fields describe one received message or track update when present

Caution: Missing, delayed, or stale fields should not be overclaimed.

### Inspect receiver coverage
```sh
antenna height + feedline + receiver position + message count
```
Expected signal: Reception changes with physical setup, not just software choice

Caution: Do not publish sensitive station details if that creates a personal privacy problem.

## Common traps
- Confusing ADS-B reception with official radar or air-traffic authority.
- Assuming every aircraft in the area must appear on your receiver.
- Ignoring stale timestamps, missing fields, antenna blockage, or receiver coverage.
- Treating receive-only SDR practice as permission to transmit or interfere.
- Using aircraft data for stalking, evasion, public-safety misuse, or harassment.

## Practice task
Draw one receive-only ADS-B path. Label aircraft broadcast, 1090 MHz signal, antenna, RTL-SDR, decoder, decoded fields, map display, timestamp, and the limits of your claim.

## Next steps
- Save an Obsidian note with [[ADS-B]], [[RTL-SDR]], [[1090 MHz]], [[Antenna Placement]], [[Decoder]], [[Aircraft Fields]], [[Timestamp]], [[Receive-Only]], and [[RF Safety]] backlinks.
- Use the antenna-length math page to estimate why 1090 MHz implies a short antenna scale.
- Use the RSSI page when you want to reason about signal-strength changes without overclaiming exact location.
- Use the sensor statistics page when message count or coverage changes need a small data note.

## Related
- [Radio and Signals topic group](/topics/rf/)
- [Antenna length math for makers](/learn/rf/antenna-length-math-for-makers/)
- [RSSI mapping for direction finding](/learn/rf/rssi-mapping-for-direction-finding/)
- [Stepper antenna sweep for direction finding](/learn/rf/stepper-antenna-sweep-for-direction-finding/)
- [Basic statistics for sensor logs](/learn/data/basic-statistics-for-sensor-logs/)
- [Make an Obsidian project note](/learn/make-an-obsidian-project-note/)
- [Turn a source video into notes](/video-notes/)
- [Review Anki-compatible decks](/decks/)

## Obsidian backlinks

Use these wiki links to connect this note inside a local maker vault:

- [[TopicLadder]]
- [[Maker Learning]]
- [[SDR Flight Tracking ADS-B First Pass]]
- [[Radio and Signals]]
- [[rf]]
- [[receive-first]]
- [[Name the signal]]
- [[Trace the receive path]]
- [[Read the fields]]
- [[Write the limits]]
- [[Radio and Signals topic group]]
- [[Antenna length math for makers]]

## Source and next routes

Source: https://topicladder.com/learn/rf/sdr-flight-tracking-adsb-first-pass/

- [Radio and Signals topic group](/topics/rf/)
- [Antenna length math for makers](/learn/rf/antenna-length-math-for-makers/)
- [RSSI mapping for direction finding](/learn/rf/rssi-mapping-for-direction-finding/)
- [Stepper antenna sweep for direction finding](/learn/rf/stepper-antenna-sweep-for-direction-finding/)
- [Basic statistics for sensor logs](/learn/data/basic-statistics-for-sensor-logs/)
- [Make an Obsidian project note](/learn/make-an-obsidian-project-note/)
- [Turn a source video into notes](/video-notes/)
- [Review Anki-compatible decks](/decks/)