- Star Trek: The Motion Picture
- Star Trek II: The Wrath of Khan
- Star Trek III: The Search for Spock
- Star Trek IV: The Voyage Home
- Star Trek V: The Final Frontier
- Star Trek VI: The Undiscovered Country
- Star Trek Generations
These Starfleet devices are positioned in the galaxy to relay subspace radio transmissions between starships and Earth to other places. The Enterprise NX-01 deployed Echo I, which was the second in a series of such amplifiers. Unfortunately, Echo I was destroyed by some particularly uncommunicative aliens.