Tok'ra homing beacon

The Tok'ra Homing beacon is a Tok'ra device responsible for detection of incoming vessels and transmitting warning signals to friendly ships to inform them of base compromises.

History
When the Tok'ra base on [{Revanna]] was attacked by Anubis' forces these devices transmitted signls to warn off any friendly ships. SG-1 had to reprogram one of these devices to let Daniel Jackson and Jacob Carter\Selmak know they were alive and to come and rescure them.