An ignition for triggering projectile

is used a detonator fuse before the projectile and delivers a pulse at impact, while the projectile contains a receiving device 22 for a pulse integrator two stages 10, 12, 14, one 10, 12 integrating the differential speed of the rocket and of the projectile to the reception of the pulse and the other 10, 14 forming the difference between the content of the first stage and the integral of the velocity of the projectile from the reception of the pulse, a threshold value detector delivering an ignition pulse when the difference is less than a predetermined limit value.