shrieker: (also ping-pedo) a single-shot directional EM pulse generator mounted in a capsule suitable for mass driver deployment.
It is a truism of tactics that active sensors, while much more effective than passive sensors, can rarely be used since they are even more effective at disclosing the user’s position to other vessels. The shrieker represents a compromise with this truism; given effective localization and a little mathematics, there is no necessity for the sensor emitter and the sensor receiver to be in the same location. Thus, it provides the means to implement this by emitting the radar/lidar pulse from a point distant from the launching vessel.
The shrieker is far from a perfect solution. It provides partial information on the location of its launcher, especially if the pre-pulse run is short, or the opposition’s sensors are sufficiently sensitive to pick up Doppler distortion in the emitted pulse; and deployments are limited inasmuch as, although directional, a shrieker can only be used in situations in which its pulse will not illuminate the launching vessel or other friendlies to the passive sensors of the opposition. Nonetheless, the additional information provided by even limited active sensor capability can make all the difference in a tactical situation.
– Blackjacket’s Dictionary