OnAirDecode MT63 with an SDR
MT63: robust keyboard chat on 64 carriers.
- Group
- Amateur: digital
- In the mode list
- Robust chat, 14.1095 MHz
What MT63 is
MT63 keyboard chat (500 / 1000 / 2000 Hz, short or long interleave, found automatically): 64 carriers with Walsh-Hadamard coded characters that survive fades and interference, 14.1095 MHz.
Frequencies and settings
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 Robust chat, 14.1095 MHz.
What OnAir shows
MT63 keyboard chat (500 / 1000 / 2000 Hz, short or long interleave, found automatically): 64 carriers with Walsh-Hadamard coded characters that survive fades and interference, 14.1095 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 MT63
Can I decode MT63 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 MT63?
Amateur radio signals are meant to be received. Receiving needs no licence in most countries; OnAir does not transmit.
Can I try MT63 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.