Covenant communications jammer (Earth-2042)

Covenant communications jammers, also known as Separatist mobile jammers, were a piece of signal jammer technology used by the Covenant and later the Confederacy of Independent Systems. On 20 BBY, during the Fall of Reach in the Clone Wars, SPARTAN-B312 assisted in destroying several of the jammers in New Andria that were blocking a signal to GRSC command.

Source

 * https://www.halopedia.org/Covenant_communications_jammer