Frequency Switching is a way of evading enemy detection of infiltration of comm systems (active or passive). Of course, nothing prevents the jammer from switching frequencies along with its opponent, and in fact jammers and sensors may switch frequencies thousands of times a second in their continuing cat and mouse games. The Andromeda Ascendant uses quantum entangled communications to send undetectable messages, thus circumventing frequency switching. Freighters such as the Eureka Maru use frequency switching to hide illegal cargo.