Three antennas above rooftop.

Automatic Link Establishment (ALE)

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Automatic Link Establishment (ALE) is a digital protocol that enables HF operators to contact one another by dialling a recipient similar to how other digital modes in the VHF/UHF bands do. Each amateur operator first programs their radio or connected computer running PCALE with their callsign and a QRG file. A QRG file (QRG meaning “What line do you belong to?”) is simply a configuration file that adds frequencies and contact callsigns for your radio or PC. After both are done you are ready to go for ALE operation.

ALE begins by scanning two lists of agreed upon frequencies. The first set are in the data regions of each HF band. In these regions, ALE operates in active mode. Active mode begins with your equipment listening to see if there is anything on each frequency. Periodicity, if a frequency is not busy, it will send a short identification so other ALE stations can listen to and rate your signal. If it does detect the frequency is busy, it will rate the signal strength/quality for every ALE stations it hears. This allows it to store a rating of each station on each frequency for later use and keep up with ionospheric changes and fluctuations in band conditions. The second mode is passive. Passive operation takes place in the voice regions of the HF bands. The only difference in passive mode is that beaconing is not performed. Instead, it overhears and rates the signals of ALE stations when they make contacts.

When an ALE operator dials a station, their radio will see if it has a frequency it knows works well for contact with that operator. If it does, it will beacon on that frequency to let the other station know it intends to make contact. If it does not have a frequency in mind it will beacon instead on a frequency it believes to have favourable conditions based on factors such as average quality of other stations, noise floor, and so on. If the other station does not respond, it will try other frequencies until it achieves a contact or it assumes contact is not possible. When the reviving station confirms to the caller that the circuit has been established, both radios alert their operators that they are connected. Unlike most digital modes in the VHF/UHF space, ALE circuit building is considerably slow, usually taking between 10 and 30 seconds. This is the result of using more than one frequency in more than one band requiring the radio to scan across a large frequency space. However, ALE enables HF contacts with an automatically high signal quality, little prearranged contact coordination, and offers a digital feature set such as text communications, message store-and-forward, and station calling.

Developed in the late 1970s and early 1980s by several radio manufacturers, ALE was initially created for the military as externally rack mounted controllers. Amateur radio operators began sporadic ALE operation in the early to mid-1990s with commercial gear, and in 2000, the first widely available software ALE controller, PCALE, became available. By 2001, the first organized and coordinated global ALE nets began. In August 2005, ham radio operators supporting emergency communication with the Red Cross used ALE for disaster relief operations following Hurricane Katrina. Afterwards, a more permanent ALE emergency/disaster relief network with a focus on interoperation between organizations was established as the Ham Radio ALE High Frequency Network. This system operates 24/7/365 and enables emergency communications and internet connectivity in the wake of disasters around the globe.

If you’re interested in trying out ALE, check out the HF ALE Group Website. If you’re lucky, you may be able to make contact now with Brian Lloyd WB6RQN who is flying round the world in his Mooney M20K 231 airplane from May 31, 2017 until 24 July 2017 retracing the historic worldwide equatorial flight route, commemorating 80 years since Amelia Earhart’s famous attempt at circumnavigating the world in 1937. Brian WB6RQN/AM Air Mobile is on High Frequency SSB, using ALE and AMD (Automatic Message Display) text messaging during the flight. AMD is just the name of the text messaging protocol using ALE. For details see Project Amelia Earhart.