OnAirDecode MFSK with an SDR
MFSK: error-corrected keyboard text.
- Group
- Amateur: digital
- Start frequency
- 14.0785 MHz
- In the mode list
- Keyboard, 14.0785 MHz
What MFSK is
MFSK is a keyboard-to-keyboard digital mode from the fldigi family.
Frequencies and settings
| Start frequency | 14.0785 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 Keyboard, 14.0785 MHz.
What OnAir shows
MFSK4 to MFSK64 keyboard modes (MFSK16 is the usual one) with forward error correction, 14.0785 MHz.
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 MFSK
Can I decode MFSK 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 MFSK?
Amateur radio signals are meant to be received. Receiving needs no licence in most countries; OnAir does not transmit.
Can I try MFSK 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.