초록 ▼

A trunked communications system that accommodates encrypted secure communications. The system uses both non-encrypted message detectors and encrypted message detectors to assure that the trunked central control unit receives the signals it must receive in order to properly allocate and maintain chan

A trunked communications system that accommodates encrypted secure communications. The system uses both non-encrypted message detectors and encrypted message detectors to assure that the trunked central control unit receives the signals it must receive in order to properly allocate and maintain channel assignments.

대표청구항 ▼

A subscriber unit for use in a secure trunked communications system, wherein the secure trunked communications system includes: at least one central controller having: means for allocating a limited number of communication channels in response to a channel acquisition request from said subscriber un

A subscriber unit for use in a secure trunked communications system, wherein the secure trunked communications system includes: at least one central controller having: means for allocating a limited number of communication channels in response to a channel acquisition request from said subscriber unit; means for maintaining said channel allocation, at least so long as said subscriber unit alternatively provides both of: a connect tone in conjunction with transmission of an unencrypted signal; and an encrypted signal transmission comprised of a data stream; means for terminating said channel allocation upon receiving either of: a disconnect signal; and an end of message signal transmitted by said subscriber unit as part of said data stream; and means for transmitting a handshake signal when said subscriber unit transmits a signal that includes said connect tone; said subscriber unit comprising: means for transmitting a channel allocation request to said central controller; means for selectively transmitting a digitally encrypted message as a data stream; means for automatically attempting to decrypt a received digitally encrypted message comprised of a data stream upon receiving such a signal, and further including means for automatically rendering a decrypted message audible following decryption; means for automatically transmitting said connect tone in parallel with transmission of a non-encrypted message; and means for receiving a non-encrypted signal and for automatically rendering said non-encrypted message audible following receipt thereof.