How to listen to airband (ATC) with SDR++

Airband is the easiest place to start with an SDR. It's analog AM, no decoders or virtual audio cables required — point SDR++ at a tower frequency in your area, set AM demodulation with a narrow bandwidth, and you'll hear pilots and controllers in real time. This guide walks you from "RTL-SDR plugged in" to "tower frequency on a hot mic" in under an hour, including a basic scanner setup that sweeps a small list of local frequencies.

What you'll have at the end

SDR++ open with the FFT and waterfall showing the 118–137 MHz aviation band. A bookmark list with your local airport's tower, ground, ATIS, approach, and departure frequencies. Single-click switching between them. Optional: scanner mode running through the bookmark list automatically, parking on any frequency that breaks squelch and resuming after the transmission ends. You'll hear pilots reading back clearances, ATIS recorded loops, ground crews getting taxi instructions — the same audio that's on LiveATC.net but tuned by your own antenna, with no streaming delay.

This is the lowest-effort guide in the wave-1 set. If you're new to SDRs, this is where to start before tackling P25/DMR decoding or trunked-system following — airband uses analog AM modulation, so there's no protocol decoding step. Tune the dial, hear voice.

What you need

Hardware. An RTL-SDR Blog v4 dongle (~$40) — any v3 or v4 works for airband, the v4's better filtering is overkill for the relatively quiet 118–137 MHz band. An SMA-to-MCX adapter and an antenna. A 1/4-wave whip cut to ~57 cm (or trim a longer whip to that length) is ideal for airband; a discone or any broadband VHF/UHF antenna also works fine. Indoor reception is viable for nearby (under 20 miles) airports; outdoor mounted antennas with line-of-sight to a tower extend that to ~50 miles. Any laptop with a USB port.

Software. SDR++ (free, runs on Windows / macOS / Linux). That's the entire software dependency. No decoder, no virtual audio cable, no command line. SDR++ has airband-suitable AM demodulation, squelch, and a scanner built in.

Time. See the frontmatter at the top of this page. Skill level. Comfortable installing an app and entering frequencies. No prior SDR experience required.

Step-by-step setup

1. Identify your local airport's frequencies

Two free lookup sources:

• AirNav.com. Search your airport (e.g., KBOS for Boston Logan). Each airport's page lists Tower, Ground, Clearance Delivery, ATIS, Approach, and Departure frequencies. Write them down or save them in a note.
• LiveATC.net. Search the airport; their "Stream Source" tab lists the same frequencies that LiveATC's volunteer feeders are receiving. Useful sanity check that the AirNav numbers are still current.

For a starter set, capture five: Tower, Ground, ATIS, Approach, and Departure. ATIS is a continuously-looped recording — great for confirming your receive setup works because there's always something to hear, day or night.

If you're not close to a Class B or Class C airport, look up the nearest Class D field (small towered airport) or — if that's also distant — try CTAF / Unicom on 122.7, 122.8, 122.9, or 123.0 MHz. CTAF is the self-announce frequency at non-towered airports; you'll hear pilots reporting position to each other.

2. Install SDR++

Download the latest SDR++ build from sdrpp.org (or the GitHub releases page). Run the installer. Plug the RTL-SDR into a USB port (a USB 2 port is fine; USB 3 sometimes causes interference on some systems). Connect the antenna.

Open SDR++. In the left sidebar, find the Source module, click the gear, and pick RTL-SDR from the dropdown. Click the ▶ play button. The FFT and waterfall should come alive across the spectrum.

3. Tune to a known-active frequency

Type your airport's ATIS frequency into the frequency box at the top (e.g., 127.875 MHz). ATIS is on a loop, so within 30 seconds you should hear a male or female synthesized voice reading the current weather and active runway.

If you hear static instead, check three things in order:

1. Demodulator mode. In the left sidebar's Radio module, set the demodulator to AM, not FM. Airband is AM modulation. This is the most common new-user mistake.
2. Bandwidth. Set bandwidth to ~10 kHz. SDR++'s default of 50 kHz for AM is too wide and lets in adjacent-channel splatter and noise; ~8–10 kHz is the airband sweet spot.
3. Frequency offset. RTL-SDRs drift slightly with temperature. If you're within a few kHz of the correct frequency but not exactly on it, you'll hear muffled or absent audio. Tune slowly with the scroll wheel until the voice clarifies. SDR++'s PPM correction under the Source settings can be calibrated for permanent fix.

4. Bookmark your frequencies

In SDR++'s left sidebar, find the Frequency Manager module. Click + to add a new entry. Give it a name (KBOS Tower), the frequency (128.800 MHz), and pick AM as the mode. Repeat for Ground, ATIS, Approach, Departure.

Once you have five bookmarks, you can single-click between them — the demodulator stays on AM, bandwidth stays at whatever you set, only the frequency changes. This is the entire workflow for casual listening.

5. Set squelch so silence stays silent

Open the Radio module's squelch section. Set squelch to a level just above the noise floor — usually around -50 to -45 dBFS for airband, but it depends on your antenna and how strong the local signals are. Test by tuning to a known-quiet frequency (any ATIS not currently playing the loop — between updates it's silent). If you hear constant hiss, raise the squelch threshold by 5 dB. If transmissions get cut off because they're slightly under threshold, lower it.

The point: when nothing's being transmitted, your speakers stay quiet. When someone keys up, you hear them immediately.

6. Set up scanner mode for sweeping

SDR++ has a built-in scanner that walks through your Frequency Manager bookmarks, parking on any frequency where squelch breaks and resuming after the transmission ends. Find the Scanner module in the sidebar, set it to scan your bookmarked list, set the dwell time (how long to stay on a frequency after a transmission ends before resuming — ~3 seconds is typical), and hit play.

Now you've got a multi-frequency airband scanner that follows whoever's transmitting. The display will jump between Tower / Ground / Approach as the air-traffic pattern dictates.

7. Tune gain for clean reception

Back in the Source module, find the gain slider. Default of ~30 dB is reasonable. For weaker signals (distant airports), try 36–40 dB but watch for the FFT noise floor lifting (sign of overload). For very strong nearby signals — like a tower 5 miles away — drop to 20–25 dB to avoid IMD products bleeding into adjacent channels.

Disable AGC if it's on. Airband transmissions are short and bursty; AGC's rolling adjustments create audible pumping on every key-up.

8. (Optional) Record interesting transmissions

SDR++'s Recorder module dumps audio to WAV files when triggered. Useful for capturing a tower clearance to listen back, or for archiving local CTAF activity if you live near a busy non-towered field. Files land in the directory configured in the Recorder module.

For systematic archiving (record everything on a frequency for hours / days), point a separate tool like rtl_fm | sox or a dedicated recorder app at the same frequency. SDR++'s Recorder is best for ad-hoc captures.

Common gotchas

You picked FM instead of AM. Airband is AM. The whole 118–137 MHz block is amplitude-modulated for historical reasons (AM tolerates simultaneous transmission better than FM — if two pilots key up at once you get a "heterodyne" warble rather than the FM "capture effect" silencing one of them). If you hear nothing but static while the waterfall shows a clear active carrier, this is almost always the fix.

Bandwidth set too wide. SDR++ defaults to 50 kHz for AM. That's three airband channels at once, and the splatter is audible. Drop to ~8–10 kHz. Below ~6 kHz starts cutting voice high frequencies and sounds muffled, but is still intelligible.

RTL-SDR frequency offset (PPM). Most RTL-SDRs are 30–80 ppm off out of the box. At 130 MHz, 50 ppm is about 6.5 kHz of offset — enough to noticeably degrade audio if you're tuned to the exact published frequency. The fix: tune to a known stable signal (a local FM broadcast station is best; tune to its exact published frequency, see how far off the carrier appears on the waterfall, compute ppm = (offset_hz / freq_hz) × 1,000,000, then enter that PPM correction in SDR++'s Source settings). Once set, it's permanent for that dongle.

Birdies on RTL-SDR around 124 MHz. Some RTL-SDR v3 sticks have an internal oscillator spur near 124 MHz that creates a constant carrier you can't tune away from. The v4 mostly fixes this with better shielding. If you see a tall, motionless spike in the FFT at exactly the same place every time, that's a birdie — ignore it and tune around it.

Indoor reception is weaker than you expect. Airband signals are line-of-sight VHF; an indoor antenna sitting on your desk near concrete walls is going to struggle. If you're hearing only the strongest tower, move the antenna to a window facing the airport or — much better — put it outside.

What to do next

For ADS-B aircraft tracking (the visual companion to airband — see the planes you're hearing on a map), the upcoming track-aircraft-ads-b guide covers dump1090 + tar1090 on a Pi. For monitoring digital public-safety traffic instead of analog air traffic, Trunk Recorder handles P25 trunked systems with per-call recording. For decoding P25 or DMR voice on a single frequency, DSD+ is the right next step. The LiveATC.net forums are a friendly place to ask questions about airband reception in your specific area; people there know which frequencies are active and what antennas work locally. AirNav.com is the canonical reference for current airport frequency assignments.

Local DIY vs. Squelch Deck

Dimension	Local DIY	Squelch Deck
Setup time	< 1 hour	~1 minute (tap the app)
Hardware cost	~$50–$60	One device
Ongoing maintenance	OS updates, dependency drift, debugging when it breaks	App updates roll through the Squelch Deck catalog
Customization ceiling	Total — you own the stack	Bounded by what apps support; you can build new apps
Skill required	Install an app, enter frequencies	Touchscreen
Best for	Anyone curious — lowest-effort SDR project	People who want it to work on a dedicated box

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Sources we drew from

• SDR++ on GitHub — releases, module documentation, RTL-SDR source config, Frequency Manager, Scanner module.
• AirNav.com — canonical reference for US airport frequency assignments.
• LiveATC.net — frequency cross-reference and active-coverage sanity check.
• rtl-sdr.com — RTL-SDR Blog v4 setup notes, PPM correction process, gain calibration walkthroughs.
• FCC Part 87 (Aviation Services) — for the airband frequency allocations and why airband uses AM.