five and spacing of the beacons is sufficiently small relative to the full span of the beacon set preferably not more than u2155 span the requirement for modulation of each individual beacon may be reduced to a simple synchronized switching to high intensity for a specific time and back to low intensity for a specific time such that the net effect of all beacons with respect to the seeker is substantially the same as in other embodiments this may simplify the design and operation of the individual beacons longer and shorter sweep times than the about 0 1 to about 3 0 seconds with about 0 1 to about 1 5 seconds preferred may be desirable whether controlled by fixed or variable means depending on beacon spacing and anticipated defensive requirements for example for about a 50 foot beacon span about a 0 5 second sweep time may be effective for about a 200 foot span a longer total time such as about 1 0 second may be effective as long as at least two modulated ir radiation beacons are within the field of view or beam width of the missile the missile thinks the aircraft is moving the distance and direction between the two beacons in the sweep time provided and responds with a correction to its intercept path in the direction of the sweep by then snapping off the last beacon and restarting the beacon set with a new modulation sweep the target or host aircraft appears to the missile.