From The RadioReference Wiki

Rockwell Collins Trademark name for an Automatic Link Establishment protocol for HF Radio Networks.

Based on a 8FSK, 2kHzBW protocol

Users included:

  • US FAA (Federal Aviation Administration)
  • US FBI (Federal Bureau of Investigations)
  • COTHEN - US Customs Over the Horizon Radio Network

SELSCAN was based on the FED-STD-1045 ALE standard, but is no longer in use today (Superseded by MIL-STD-188-141)