Al et al:

The HF digital standard you're thinking of is 
https://www.sigidwiki.com/wiki/MIL-STD-188-110_Serial . Army MARS has been using this on their nets for years. It supports encryption which  is used extensively. I believe there is a Ham version, too. I'll have to dig through my archived emails to find a link.

73 de
Gene Smar AD3F


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