What hardware should I start with?
Good news: software-defined radio has made listening to the spectrum ridiculously affordable. Here's the honest guide, with no useless gear.
Option 1 — the RTL-SDR dongle (~$30–40): start here
A lighter-sized USB stick descended from DVB-T tuners. The reference: RTL-SDR Blog V3 or V4 (avoid no-name clones — often noisy, no TCXO).
- Coverage ~500 kHz to 1766 MHz (V3/V4 even receives HF via "direct sampling").
- 2.4 MSps: a ~2.4 MHz window — plenty for FM, aviation, ISM, ADS-B.
- Receive-only: zero regulatory risk.
- Best of all: it works right here — Explore tab → "Plug in my SDR (USB)" (Chrome/Edge). Nothing to install, the browser drives it.
Option 2 — the HackRF One (~$300–350): to go further
- Coverage 1 MHz to 6 GHz: it sees 2.4 GHz (WiFi, drones), invisible to an RTL-SDR.
- Up to 20 MSps: windows ten times wider.
- Can transmit (half-duplex) — which is illegal without a licence: see Légal & sécurité. The academy stays receive-only.
- It's the heart of OpenHertz's Pi appliance, and it also works here over WebUSB.
| RTL-SDR V3/V4 | HackRF One | |
|---|---|---|
| Price | ~$35 | ~$330 |
| Coverage | 0.5–1766 MHz | 1–6000 MHz |
| Width (MSps) | 2.4 | 20 |
| Transmit | no | yes (licence!) |
| First buy? | yes | once you know why |
Your first antennas
The bundled antenna is a compromise. Soon you'll want: an adjustable dipole (the RTL-SDR Blog kit is excellent), a magnetic λ/4 to stick on a car roof or radiator, and later one dedicated antenna per band — see Antennes.
Setup per operating system
- Windows: run Zadig (zadig.akeo.ie), select the dongle, install the WinUSB driver. Required for WebUSB.
- Linux: a udev rule to allow non-root access, then replug:
echo 'SUBSYSTEM=="usb", ATTRS{idVendor}=="0bda", MODE="0666"' | sudo tee /etc/udev/rules.d/20-rtlsdr.rules && sudo udevadm control --reload(for a HackRF, use idVendor1d50.) - macOS: nothing to do.
- Then Chrome/Edge → Explore → Plug in my SDR.
Traps to avoid
- $12 clones: frequency drift, noise, fake "R820T2". The V3/V4's TCXO genuinely matters (e.g. to stay locked on ADS-B).
- "Miracle" wideband antennas with fantasy gain figures.
- Buying a HackRF "for later" before exhausting what an RTL-SDR can teach — which is a lot.
👉 Hardware plugged in? Go check the noise floor: First contact
Related: Le HackRF One · Antennes · Bandes intéressantes à explorer