标准资料网-标准资料免费资源平台

MIL-STD-188/140, MILITARY STANDARD: EQUIPMENT TECHNICAL DESIGN STANDARDS FOR COMMON LONG HAUL/TACTICAL RADIO COMMUNICATIONS IN THE LOW FREQUENCY BAND AND LOWER FREQUENCY BANDS (03 APR 1981)., This standard establishes minimum performance requirements in the form of standards and design objectives (DOs) to ensure interoperability of future communications equipment in the Extremely Low Frequency (ELF), Infra Low Frequency (ILF), Very Low Frequency (VLF) and Low Frequency (LF) bands. The frequency ranges of military communications equipment have been established as a result of band characteristics which do not necessarily depend upon administrative or scientific frequency band definitions. For example, in the area above ELF and ILF the military band of communications interest lies between 14 kilohertz (kHz) and 200 KHz, which extends into both VLF and LF bands. Also, efficient use of the limited bandwidth available at these lower frequencies precludes most analog modulation techniques; thus, this standard applies only to radio communication systems involving transmission of digital information.