Mode APRS AFSK

APRS and AX.25 packet radio, 1200 bd AFSK on VHF (not LoRa APRS).

Group	Amateur: voice & packet
Default frequency	144.8 MHz
Default sample rate	2 Msps
In the mode list	AFSK, 144.8 MHz

Step-by-step: Tutorial-APRS-AFSK

What APRS (AFSK) is

APRS is the amateur packet system that shares positions, weather and messages (AX.25 at 1200 baud AFSK on 144.800 MHz in Europe).

Frequencies and settings

Setting	Value
Start frequency	144.8 MHz
Tuning range of the mode table	25 to 1000 MHz
Sample rate asked	2 Msps
Lowest working rate	1 Msps
Channel width	25 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 AFSK, 144.8 MHz.

What OnAir shows

APRS and AX.25 packet radio (1200 bd AFSK), 144.800 MHz in Europe; LoRa APRS is its own entry.

The mode's own tab has these screens: Stations, Map, Packets. The other tabs (Overview, Receiver, Scan, History) are described on the Main window page.

Tips and caveats

• Checked with generated signals and impairments; recordings of real signals welcome.
• Which radio: Usually yes for narrowband signals: an RTL-SDR tunes roughly 24 MHz to 1.7 GHz at up to about 2.4 Msps. Wide signals such as TV channels need a faster radio, and OnAir says next to the source what the selected radio can do.
• Try it without a radio: most modes include a built-in synthetic test signal, so you can open the screen and try the controls first.
• Receiving and the law: Amateur radio signals are meant to be received. Receiving needs no licence in most countries; OnAir does not transmit. Voice needs a codec library you install yourself. See Legal.

Related pages

• Voice codecs
• All modes, Amateur: voice & packet
• Supported radios, Troubleshooting, FAQ
• More in Amateur: voice & packet: FreeDV, M17, D-STAR, LoRa APRS, MeshCom