The TETRA standard is used in radios worldwide. Security researchers have found multiple vulnerabilities in the underlying cryptography and its implementation, including issues that allow for the decryption of traffic.
Just out of curiosity, when you say you “regularly pick them up”, is it intelligible audio (clear voice conversations) or is it the digital modulation that’s leaking over to your freqs? I don’t have a good answer for the first problem since that shouldn’t be possible unless there’s an open patch somewhere that shouldn’t be enabled, but I can 100% believe the second problem. In either case, it’s poor practice from the radio maintainer of the offending system… and it’s illegal regardless since their license is not valid for out-of-band transmissions and the modulation format is probably not licensed for use on those freqs. You’d be surprised, but FCC enforcement will take that very seriously.
Just out of curiosity, when you say you “regularly pick them up”, is it intelligible audio (clear voice conversations) or is it the digital modulation that’s leaking over to your freqs? I don’t have a good answer for the first problem since that shouldn’t be possible unless there’s an open patch somewhere that shouldn’t be enabled, but I can 100% believe the second problem. In either case, it’s poor practice from the radio maintainer of the offending system… and it’s illegal regardless since their license is not valid for out-of-band transmissions and the modulation format is probably not licensed for use on those freqs. You’d be surprised, but FCC enforcement will take that very seriously.