ALE

As you tune the ham bands you may be hearing some strange sounding signals. Chances are some of those signals are ALE or Automatic Link Establishment.

According to the website hflink.com, Automatic Link Establishment is the de-facto worldwide standard for initiating and sustaining communications using High Frequency radio. HF radio conveys signals via ionospheric propagation, which is a constantly changing medium.

To find ALE you can look on http://hflink.com/channels/ and look at the ALE frequency list.

If you are interested in trying out ALE you can download one of 2 software packages here

PC-ALE is ALE Software for PC by Charles Brain G4GUO
Full Mil-Standard Automatic Link Establishment operation using HF SSB or ham radio transceivers. Advanced features include Scanning, Sounding, Channel Groups, Calling, Netcalls, Allcalls, AMD, DBM, DTM, LQA, and many many other fuctions. Use with a PC sound device and CAT control interface. High speed PSK ARQ HF modem included. User supported by HFLINK Group. Free for ham radio use.

MULTIPSK by Patrick F6CTE
Multimode Ham Radio Software (with ALE) for PC
Includes basic ALE functions for calling and operating using ham radio ALE methods, for individual calls and Netcalls. AMD, FAE-ARQ, Unproto modes for texting. Many different modes and features. Use with a PC sound device and CAT control interface. Free to try and use. More features such as scanning and alerting with user license.

Once you download the software, you can read the configuration instructions here