Page "Automatic link establishment" Paragraph 9

ALE evolved from older HF radio selective calling technology.

It combined existing channel-scanning selective calling concepts with microprocessors ( enabling FEC decoding and quality scoring decisions ), burst transmissions ( minimizing co-channel interference ), and transponding ( allowing unattended operation and incoming-call signalling ).

Early ALE systems were developed in the late 1970s and early 1980s by several radio manufacturers.

The first ALE-family controller units were external rack mounted controllers connected to control military radios, and were rarely interoperable across vendors.