A radar seeker transient suppressor for an anti-radar homing missile in which glint effects upset the smooth tracking of a target by apparently changing the target position spasmodically. A seeker output signal is derived which is at least substantially independent of body movement e.g. the target sightline angle signal rather than the look angle signal (i.e. relative to a space reference rather than a body reference). This signal is used to control the steering either filtered or unfiltered according to whether the difference exceeds a threshold value or not. Both azimuth and elevation channels are treated similarly and in unison. An excessive filtered/unfiltered difference in either channel causes use of the filtered signal in both. A double integrating filter may be employed to avoid the relative displacement of output and input signals when the input is, or contains, a ramp component.
