OnAirDecode Q65 with an SDR
Q65: weak-signal, EME and scatter contacts.
- Group
- Amateur: digital
- Start frequency
- 14.1 MHz
- In the mode list
- WSJT, 14.100 MHz
What Q65 is
Q65 is a weak-signal digital mode of the WSJT family, decoded by the same receiver as FT8.
Frequencies and settings
| Start frequency | 14.1 MHz |
|---|---|
| Tuning range of the mode table | 1 to 30 MHz |
| Sample rate asked | 2 Msps |
| Lowest working rate | 250 ksps |
| Channel width | 3 kHz |
OnAir takes any frequency you type; the numbers above are the mode's starting point and the range its table describes. In the app the shortcut label is WSJT, 14.100 MHz.
What OnAir shows
Q65 (A to E, 15 s to 5 min periods) for EME, scatter and weak-signal work: Q-ary repeat-accumulate code, 65-FSK.
The mode's own tab has these views: Decodes, Map. The other tabs (Overview, Receiver, Scan, History) are described on the main window page.
Limits and what it was checked with
Checked with generated signals and impairments; recordings of real signals welcome.
Which radio you need
This is a shortwave mode, so the radio has to tune HF. An SDRplay, Airspy HF+ or an RTL-SDR in direct-sampling mode do that directly; with a HackRF an HF upconverter or a direct-sampling receiver is the usual route. A long wire or loop antenna matters more than the radio.
Receiving and the law
Questions about Q65
Can I decode Q65 with an RTL-SDR?
An RTL-SDR can receive HF only in direct-sampling mode, which OnAir offers in its radio settings; results depend on the antenna. SDRplay and Airspy HF+ radios are better suited.
Is it legal to receive Q65?
Amateur radio signals are meant to be received. Receiving needs no licence in most countries; OnAir does not transmit.
Can I try Q65 in OnAir without a radio?
Yes. Most modes include a built-in synthetic test signal, so you can open the screen and try the controls before you own a radio.