, ▁the ▁N uc lear ▁elect romagnet ic ▁pul se ▁( NE MP ). ▁ ▁Canada ▁Other ▁countries ▁were ▁also ▁involved ▁in ▁early ▁AB M ▁research . ▁A ▁more ▁advanced ▁project ▁was ▁at ▁C AR DE ▁in ▁Canada , ▁which ▁research ed ▁the ▁main ▁problems ▁of ▁AB M ▁systems . ▁A ▁key ▁problem ▁with ▁any ▁rad ar ▁system ▁is ▁that ▁the ▁signal ▁is ▁in ▁the ▁form ▁of ▁a ▁cone , ▁which ▁spread s ▁with ▁distance ▁from ▁the ▁transmit ter . ▁For ▁long - distance ▁inter ception s ▁like ▁AB M ▁systems , ▁the ▁inher ent ▁in ac cur acy ▁of ▁the ▁rad ar ▁makes ▁an ▁inter ception ▁difficult . ▁C AR DE ▁considered ▁using ▁a ▁terminal ▁guidance ▁system ▁to ▁address ▁the ▁accuracy ▁concerns , ▁and ▁developed ▁several ▁advanced ▁inf ra red ▁detect ors ▁for ▁this ▁role . ▁They ▁also ▁studied ▁a ▁number ▁of ▁miss ile ▁air frame ▁designs , ▁a ▁new ▁and ▁much ▁more ▁powerful ▁solid ▁ro cket ▁fuel , ▁and ▁numerous ▁systems ▁for ▁testing ▁it ▁all . ▁After ▁a ▁series ▁of ▁dr astic ▁budget ▁redu ctions ▁during ▁the ▁late ▁ 1 9 5 0 s ▁the ▁research ▁ended . ▁One ▁off sh oot ▁of ▁the ▁project ▁was ▁Ger ald ▁Bull ' s ▁system ▁for ▁in exp ensive ▁high - speed ▁testing , ▁consisting ▁of ▁miss ile ▁air frames ▁shot ▁from ▁a ▁sab ot ▁round , ▁which ▁would ▁later ▁be ▁the ▁basis ▁of ▁Project ▁H AR P . ▁Another ▁was ▁the ▁CR V 7 ▁and ▁Black ▁Br ant ▁rock ets , ▁which ▁used