Jamming code

From SGCommand

"The enemy has engaged counter-measures that are preventing our ability to transport."

—Hermiod

Jamming codes are a counter measure to Asgard transporters used by the Wraith. Developed quickly after the arrival of the Daedalus in the Pegasus galaxy, the jamming codes prevent a transporter lock, which effectively neutralizes the transporters as a weapons delivery system into Hive Ships. Even with the advent of the Wraith civil war, the codes are still used unchanged.

During their brief alliance with the Atlantis expedition, the hive of Michael Kenmore sent their jamming codes to the Tau'ri, but they proved ineffective against when the hive ship broke the alliance. (ATL: "The Siege, Part 1", "The Hive", "Allies")

When in close proximity to a Black hole, the jamming codes are ineffective. (SG1: "The Pegasus Project")