The primary source is the NATO Standardization Office (NSO) through the . Go to the official URL: nso.nato.int or search for "NATO NSDD."
This article provides a comprehensive overview of STANAG 4157, explains why it is vital, discusses how it differs from other standards like STANAG 3910 and MIL-STD-1553, and—most importantly—guides you on how to legally and safely obtain the official . What Exactly is STANAG 4157? Formally titled "Electrical Characteristics of a Digital Time Division Multiplexed Data Bus for Military Applications" (exact wording may vary by edition), STANAG 4157 defines the physical and electrical properties of a high-speed data bus. stanag 4157 pdf
Some public documents are freely downloadable, but STANAGs are often export-controlled. You may need to create a registered account. For contractors, using your .mil or corporate defense email is recommended. The primary source is the NATO Standardization Office