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MIL-STD-188/140A, MILITARY STANDARD: EQUIPMENT TECHNICAL DESIGN STANDARDS FOR COMMON LONG HAUL/TACTICAL RADIO COMMUNICATIONS IN THE LOW FREQUENCY BAND AND LOWER FREQUENCY BANDS (01 MAY 1990)., This standard establishes minimum performance requirements in the form of Technical Design Standards and Design Objectives (DO) that will ensure interoperability of future radio subsystems equipment in the VLF and LF bands. Performance requirements for experimental or developmental extremely low frequency (ELF and ultra low frequency (ULF) are not addressed. The frequency ranges of military communications equipment have been established as a result of band characteristics which do not necessarily depend upon administrative or technical frequency band definitions. For example, in the area of the electromagnetic spectrum above ELF, that portion of application to military broadcast communications is found between 14 kHz and 200 kHz. This portion in fact extends into both the VLF adn LF bands. Efficient use of the limited bandwidth available at these lower frequencies precludes most analog modulation techniques. This standard, therefore applies primarily to those radio communications equipment and systems which are involved in the transmission of single and multi-channel teletypewriter, data and facsimile information.