This standard specifies the basic performance requirements for backpack-based radiation-detection systems (BRDs) used in homeland security applications. BRDs shall detect gamma radiation and may include neutron detection and/or the identification of gamma-ray emitting radionuclides. They are typically worn by the user during operation but may also be used as temporary area monitors. This standard establishes the radiological performance and testing requirements and those requirements associated with the expected electrical, mechanical, and environmental conditions while in use.