HEMP performance assessment of an AT&T 4 ESS digital switch

AT&T has conducted a test program to assess the performance of the largest switch in AT&T's network, the AT&T 4 ESS switch, when subjected to the effects of high-altitude electromagnetic pulse (HEMP). The methodology and results of these tests are presented. In this test program, the switch under test was surrounded by as little external electromagnetic shielding as possible.<>