Feedback pulse
A feedback pulse or feedback surge was a burst of energy which travelled in an opposing direction of pre-existing energy stream, which has the capability of disrupting the initial transmission.

In 2153, Lieutenant Reed and Major Hayes initiated a feedback pulse by reversing polarity on 's plasma coils, in an effort to counter an attack by a Sphere-Builder who was attempting to destroy the ship. The plan was successful, and the alien was thrown clear of Enterprises warp core. ()

In 2154, a group of Augments left over from Earth's Eugenics Wars initiated a feedback pulse by amplifying a thousand percent a self-destruct command which Hoshi Sato had transmitted to Cold Station 12, which the Augments had taken over. The pulse had the effect of taking Enterprises communication system offline. ()

In an alternate timeline in 2165, Jonathan Archer initiated a feedback pulse in Enterprises warp core, in an attempt to trigger a subspace implosion with which to destroy interspatial parasites which had infected his hippocampus, impairing his ability to form new long-term memories. As the parasites existed in a state of interspatial flux, existing outside of normal time, destroying them in the present also had the effect of neutralizing them in the past, resulting in the creation of a new timeline in which the infection never occurred in the first place. ()'

In 2273, a feedback surge burned Chekov at his bridge station when the  was probed by V'ger. Chekov only received a mild shock, but had to be taken to sickbay where his hand was treated. () 

In 2366, The Calamarain used feedback pulses against Q to torment him when the USS Enterprise-D attempted to move the Bre'el IV moon back into orbit. One of the feedback pulses electrocuted Data who had to have his positronic net reset in Sickbay. Q managed to defeat the Calamarain and get his powers back and banished them to the far side of the galaxy.  (TNG:"Deja Q")     

In 2370, a feedback pulse was created along the particle beam of a phaser beam which the crew of the  was using to drill beneath the surface of the planet Atrea IV. The pulse was created as a result of the phaser beam impacting a pocket of magnesite ore, causing the crew to believe that they were going to have to terminate the beam and restart the process in a new location. This proved not to be necessary, however, when Juliana Tainer, a scientist working on the project, managed to adjust the phaser harmonics to compensate for the pulse. ()

In 2374, Seven of Nine created a feedback surge to incapacitate the Hirogen Idrin. Idrin received a mild shock because he wasn't responding to diplomacy. ()

In 2375, a Borg sphere used a feedback pulse to invert a phaser beam being fired at the sphere by the . ()

The next year, Kathryn Janeway, Voyagers captain, ordered  B'Elanna Torres to send a feedback pulse along a tractor beam being utilized by a group of adolescent Borg drones in an attempt to tear Voyagers deflector dish from the rest of the ship. Rerouting warp plasma, Torres was successful, and the pulse successfully overloaded the Borg cube's shield matrix, which drew power from the same grid as the tractor beam. This allowed the Voyager crew to obtain a transporter lock on several of their crewmembers who were being held captive aboard the cube. ()

In 2377, an interstellar trader named Gar attempted to use a feedback pulse to destabilize a tractor beam with which the Voyager crew had locked onto his ship. Although Ensign Kim initially attempted to compensate for the pulse, Captain Janeway instead ordered him to simply beam Gar into Voyagers brig, so they could pursue their investigation into the whereabouts of their EMH, whose program Gar had stolen. ()

In 2378 Seven and Chakotay crash landed on Ledos after hitting an energy barrier. While they tried to breach it so Voyager could pick them up a little girl wearing Hematite beads got too close to the deflector dish and the resulting feedback pulse knocks her out. ()
Communications technology