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Airspy vs RTL-SDR vs HackRF for Scanning
For scanning with GopherTrunk, the honest ranking is: RTL-SDR for value, Airspy for tough RF, HackRF only if you also need its range or transmit. All three are USB software-defined radios GopherTrunk drives natively, but they are built for different jobs — and for P25/DMR/NXDN trunk-tracking the cheapest one is usually right.
Key takeaways RTL-SDR (8-bit, ~$35): the default — cheap, plenty for a clean single site. Airspy (12-bit, ~$110–170): far more dynamic range and wider capture — the pick for weak, busy, or multi-site RF. HackRF (8-bit, 1 MHz–6 GHz + TX, ~$150): huge range and transmit, but overkill for scanning. Bits buy dynamic range, not audio fidelity. None decode AES encryption.
Head-to-head
| RTL-SDR Blog V4 | Airspy R2 / Mini | HackRF One | |
|---|---|---|---|
| ADC | 8-bit | 12-bit | 8-bit |
| Frequency range | ~500 kHz–1.77 GHz | ~24 MHz–1.8 GHz | 1 MHz–6 GHz |
| Capture bandwidth | ~2.4 MHz | ~6–10 MHz | ~20 MHz |
| Dynamic range | Fair | Best | Fair |
| Transmit | No | No | Yes (licensed) |
| Best for | Value / single site | Tough / busy / multi-site | Range + TX projects |
| GopherTrunk uses | RX | RX | RX only |
| Approx price | ~$40 | ~$110–170 | ~$150 |
Bits are about dynamic range, not fidelity. Decoded P25 voice is recovered or it is not — a 12-bit ADC does not make it “sound better.” What the extra bits buy is headroom: an Airspy keeps decoding a weak control channel while a strong nearby pager or FM station would drive an 8-bit RTL-SDR or HackRF into overload. In easy RF, all three sound identical.
When an RTL-SDR is all you need
Most people scanning one local trunked system never need more than a $35 RTL-SDR. One dongle follows one control channel and its voice grants cleanly, it has a real TCXO so it stays locked, and GopherTrunk decodes the same P25/DMR/NXDN/TETRA a radio ten times the price would. If your target signal is reasonably strong and you are tracking a single site, stop here — spend the savings on a better antenna instead.
When to step up to an Airspy
The Airspy earns its price in exactly two situations:
- Weak or congested RF. Its 12-bit front end pulls voice out of conditions that push an 8-bit dongle into overload — a distant control channel next to a strong local transmitter, or an intermod-heavy urban band.
- Multi-site / wideband monitoring. With up to ~10 MHz of capture (R2), GopherTrunk can channelize several control channels from one radio at once, instead of running a pool of dongles.
If your problem is dynamic range or bandwidth, the Airspy is the right tool. If it is simply low signal, an LNA on any dongle may be the cheaper fix first.
When a HackRF makes sense (rarely, for scanning)
The HackRF One is a superb general-purpose SDR — 1 MHz to 6 GHz, ~20 MHz capture, and it can transmit. GopherTrunk drives it as a receiver just fine. But for scanning specifically it is the wrong buy: its 8-bit ADC gives it less dynamic range than an Airspy, its 6 GHz reach and transmit are irrelevant to receive-only VHF/UHF decoding, and transmit legally needs a license. Buy a HackRF if you already want it for RF experimentation, satellite work, or protocol hacking — and enjoy that it scans too. Do not buy one just to scan.
GopherTrunk uses receive only. Even on the HackRF, GopherTrunk never transmits. That is a feature you are paying for and will not use if scanning is your only goal.
How to choose
- Single local system, normal signal? RTL-SDR. Done.
- Weak / busy / intermod-heavy RF? Airspy R2 or Mini.
- Many sites or control channels across a band? Airspy R2 to channelize, or a multi-dongle pool.
- Want HF too? An Airspy HF+ Discovery or a V4’s upconverter.
- Already own / want a HackRF? GopherTrunk will use it — just know it is more radio than scanning needs.
Where to buy
Airspy is sold through distributors rather than direct Amazon listings, so use a search link; the HackRF and RTL-SDR have fixed listings.
Bottom line
Buy an RTL-SDR unless you have a reason not to — it decodes the same digital voice for a third the price. Move to a 12-bit Airspy when your RF is genuinely weak, busy, or multi-site. Reach for a HackRF only if you also want its 6 GHz range or transmit for other projects. Whichever you pick, no SDR decodes encryption, and the software is free. For the full ranked lineup see the best SDR for GopherTrunk.
Frequently asked questions
Which is best for scanning: Airspy, RTL-SDR, or HackRF?
For most people an RTL-SDR (around $35) is the best value and decodes P25/DMR/NXDN just as well as anything. Step up to a 12-bit Airspy (around $110–170) only when your RF is weak, congested, or you want to channelize many signals from one wideband capture. A HackRF is overkill for scanning — its extra reach and transmit are wasted on receive-only VHF/UHF.
Is an Airspy really better than an RTL-SDR?
In tough conditions, yes. The Airspy’s 12-bit ADC has far more dynamic range than an 8-bit RTL-SDR, so it holds onto weak signals in the presence of strong ones without overloading, and its wider capture lets GopherTrunk channelize multiple control channels at once. On a clean, single-site system the RTL-SDR decodes the same voice.
Should I buy a HackRF for GopherTrunk?
Only if you also need its capabilities for other projects. The HackRF covers 1 MHz to 6 GHz and can transmit, but its 8-bit ADC has less dynamic range than an Airspy, and scanning uses none of the 6 GHz reach or TX. GopherTrunk uses it receive-only; it works but is more radio than scanning needs.
Does more bits mean better audio?
Not directly — decoded P25/DMR voice is either recovered or it is not. More ADC bits mean more dynamic range, so a 12-bit Airspy keeps decoding when a strong nearby signal would push an 8-bit RTL-SDR or HackRF into overload. In easy RF the audio is identical; the bits buy you resilience, not fidelity.
Can any of them decode encrypted police?
No. Airspy, RTL-SDR, and HackRF are all just receivers — none can decode AES-encrypted talkgroups, and neither can any scanner. GopherTrunk decodes clear P25/DMR/NXDN/TETRA only. Buy based on the systems still in the clear.
Is the HackRF's transmit useful for scanning?
No. Scanning is receive-only, and GopherTrunk never transmits. HackRF’s TX is for other RF projects and legally needs a license. If you only want to scan, you are paying for a feature you will not use.