Mode HF ALE

HF ALE: who calls whom, soundings and AMD messages.

Group	HF utility
Default frequency	14.109 MHz
Default sample rate	2 Msps
In the mode list	Link establishment, 14.109 MHz

Step-by-step: Tutorial-HF-ALE

What HF ALE is

Automatic Link Establishment (2G ALE) is the protocol HF stations use to call each other and agree on a working channel.

Frequencies and settings

2G automatic link establishment (MIL-STD-188-141 / FED-STD-1045) on HF.

Setting	Value
Start frequency	14.109 MHz
Tuning range of the mode table	1.5 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 Link establishment, 14.109 MHz.

What OnAir shows

Who calls whom: soundings, individual, net and group calls, responses and links, AMD messages, LQA reports, with BER and SNR; the stations heard.

The mode's own tab has these screens: Events, Stations, Words. 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: 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.
• 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: Some HF utility traffic belongs to governments or the military. Receiving is legal in many countries, but rules differ. Check them where you live. See Legal.

Related pages

• All modes, HF utility
• Supported radios, Troubleshooting, FAQ
• More in HF utility: Datawell Buoy HF Link, CODAR / HF ocean radar, HF beacons