System for providing encryption and decryption of voice and data transmissions to and from an aircraft

• US 4,903,298 A
• Filed: 07/27/1988
• Issued: 02/20/1990
• Est. Priority Date: 07/27/1988
• Status: Expired due to Fees

• Current Assignee: Sundstrand Data Control, Inc. (Rtx Corporation)
• Original Assignee: Sundstrand Data Control, Inc. (Rtx Corporation)
• Inventors: Cline, James D.
• Primary Examiner(s): Buczinski, Stephen C.
• Assistant Examiner(s): GREGORY, BERNARR E
• Application Number:
  US07/225,065
• Time in Patent Office: 573 Days
• Field of Search: 380/6, 380/9, 380/52, 380/53, 380/59, 380/49, 380/50, 364/424.05, 379/58, 379/62, 455/54, 455/66, 455/89, 455/98
• US Class Current: 380/270
• CPC Class Codes: H04K 1/00 Secret communication

Abstract

A data communication system for an aircraft includes a voice encryption unit that is selectably included in the audio path between a user and a radio. The data communication system is interconnected so that the unencrypted audio path of a user is isolated from other users, thus providing the user with a secure, private communications link within the aircraft, as well as between the aircraft and a ground station. The system includes an audio path from the cockpit to the encryption unit and an audio path from the passenger cabin to the encryption unit, and further includes a control unit in each of the cockpit and the cabin so that control of the encryption unit can be selectably switched between the cockpit and the passenger cabin.

Claims

1. A communication system for an aircraft that selectably provides an encrypted communication path between a user and a selected radio transceiver, said system comprising:

at least one first voice communication device in the cockpit of the aircraft that responds to the voice of a person in the cockpit to transmit a first communication device audio output signal, and that responds to a first communication device audio input signal to generate a first audible output signal;

a second voice communication device in the passenger cabin of the aircraft that responds to the voice of a person in the passenger cabin to transmit a second communication device audio output signal, and that responds to a second communication device audio input signal to generate a second audible output signal;

a first radio transceiver that receives a first transceiver audio input signal and generates a modulated radio frequency output signal responsive thereto, and that receives a modulated radio frequency input signal and generates a first transceiver audio output signal responsive thereto;

a second radio transceiver that receives a second transceiver audio input signal and generates a modulated radio frequency output signal responsive thereto, and that receives a modulated radio frequency input signal and generates a second transceiver audio output signal responsive thereto;

an encryption/decryption system that includes an encryption/decryption module, a first control unit located in said cockpit and a second control unit located in said passenger cabin, each control unit having a plurality of switches, said encryption/ decryption module responsive to an intelligible audio input signal to generate an encrypted audio output signal in accordance with a selected encryption key, said encryption/decryption module further responsive to an encrypted audio input signal to generate an intelligible output signal, said encryption/ decryption system interposed between said first and second voice communication devices and said first and second transceivers and responsive to said switches on said control units so that;

said encryption/decryption system receives said first and second communication device audio output signals and selectably provides one of said first and second communication device audio output signals as said intelligible audio input signal to said encryption/decryption module to be encrypted therein;

said encryption/decryption system selectably provides said encrypted audio output signal as one of said first and second transceiver audio input signals while providing the other of said first and second communication device audio output signals as the other of said first and second transceiver electrical input signals;

said encryption/decryption system receives said first and second transceiver audio output signals and selectably provides one of said first and second transceiver audio output signals as said encrypted input signal to said encryption/ decryption module to be unencrypted therein; and

said encryption/decryption system selectably provides said intelligible audio output signal from said encryption/decryption module as one of said first and second communication device audio input signals while providing the other of said first and second transceiver electrical output signals as the other of said first and second communication device audio input signals

2. The communication system as defined in claim 1, wherein one of said control units is disabled when the other of said control units is enabled so that only said enabled control unit controls said encryption/decryption system.

3. The communication system as defined in claim 2, wherein said control unit in said passenger cabin is subordinate to said control unit in said cockpit so that the selection of the enabled control unit is determined by said control unit in said cockpit.

4. The communication system as defined in claim 1, wherein said first and second communication device audio inputs are electrically isolated so that said intelligible audio input and output signals provided to one of said first and second communication devices are not provided to the other of said first and second communication devices.

5. The communication system as defined in claim 1, wherein one of said second communication device is a radio telephone handset in the cabin of said aircraft, said aircraft further including a second radio telephone handset in the cockpit of the aircraft, said encryption/decryption system including circuitry to selectably electrically isolate said radio telephone handset in the cabin from said radio telephone handset in the cockpit so that only one of said radio telephone handsets can transmit audio signals to and receive audio signals from said encryption/ decryption module at any one time.

6. An aircraft communications system that selectably provides an encrypted communication path between a selected user location and a selected radio transceiver, said system comprising:

a first user location comprising a first voice communication device that receives an audio input from a user at that first location and transmits a first voice communication device electrical output signal responsive thereto and that receives a first voice communication device electrical input signal and generates an audio output perceivable to the user at the first location;

a second user location, remote from said first user location, comprising a second voice communication device that receives an audio input from a user at that second location and transmits a second voice communication device electrical output signal responsive thereto and that receives a second voice communication device electrical signal and generates an audio output perceivable to the user at the second location;

a first radio transceiver that receives a first transceiver electrical input signal and generates a modulated radio frequency output signal responsive to the first transceiver electrical input signal, and that receives a modulated radio frequency input signal and generates a first transceiver electrical output signal responsive to the radio frequency input signal;

a second radio transceiver that receives a second transceiver electrical input signal and generates a modulated radio frequency output signal responsive to the second transceiver electrical input signal, and that receives a modulated radio frequency input signal and generates a second transceiver electrical output signal responsive to the radio frequency input signal;

an encryption/decryption system that includes an encryption/decryption module, said encryption/ decryption module responsive to an electrical input signal representing intelligible audio input to generate an encrypted electrical output signal in accordance with a selected encryption key, said encryption/decryption module further responsive to an electrical input signal representing encrypted audio input to generate an electrical output signal representing intelligible audio output, said encryption/decryption system interposed between said first and second voice communication devices and said first and second transceivers so that;

said encryption/decryption system receives said first and second voice communication device electrical output signals and selectably provides one of said first and second voice communication device electrical output signals as an unencrypted input to said encryption/decryption module to be encrypted therein;

said encryption/decryption system provides said first and second transceiver electrical input signals to said first and second radio transceivers, respectively, and selectably provides said encrypted electrical output signal from said encryption/decryption module as one of said first and second transceiver electrical input signals while providing the other of said first and second voice communication device electrical output signals as the other of said first and second transceiver electrical input signals;

said encryption/decryption system receives said first and second transceiver electrical output signals and selectably provides one of said first and second transceiver electrical output signals as the encrypted input signal to said encryption/decryption module to be unencrypted therein;

said encryption/decryption system provides said first and second voice communication device input signals to said first and second voice communication devices, respectively, and selectably provides said unencrypted electrical output signal from said encryption/decryption module as one of said first and second voice communication device electrical input signals while providing the other of said first and second transceiver electrical output signals as the other of said first and second voice communication device electrical input signals.

7. The communication system as defined in claim 6, wherein said first user location is in the cockpit of an aircraft and wherein said second user location is in the cabin of the aircraft.

8. The communication system as defined in claim 6, further including a first control panel at said first user location and a second control panel at said second user location, said control panels including switches electrically connected to said encryption/decryption system and operable to select an input to and an output from said encryption/decryption module.

9. The communication system as defined in claim 8, wherein one of said first and second control panels further includes a switch that is operable to select which of said first and second control panels is enabled to control said encryption/decryption system.

10. The communication system as defined in claim 9, wherein said one of said first and second control panels further includes a switch that selects which of said first and second transceivers has its electrical output connected to receive the encrypted output from said encryption/ decryption module and has its electrical input connected to provide the encrypted input to said encryption/decryption module.

11. The communication system as defined in claim 6, wherein at least one of said first and second voice communication devices and a corresponding one of said first and second transceivers comprise a UHF radiotelephone.

12. The communication system as defined in claim 6, wherein at least one of said first and second transceivers is a VHF transceiver.

13. A radio communication system for an aircraft that includes at least first and second radio transceivers and at least first and second locations within said aircraft having audio communication equipment for providing input signals to and receiving output signals from said transceivers, said radio communication system comprising:

an encryption/decryption module that receives an unencrypted input and provides an encrypted output responsive thereto and that receives an encrypted input and provides an unencrypted output responsive thereto; and

a reconfigurable interconnection circuit that selectably interconnects inputs to and outputs from said encryption/decryption module, said interconnection circuit providing a first interconnection path through said encryption/decryption unit that connects the audio communication equipment from a selected one of said first and second locations to the unencrypted input and the unencrypted output of said encryption/decryption module and that connects the encrypted input and the encrypted output of said encryption/decryption module to a selected one of said first and second transceivers, said interconnection circuit providing electrical isolation between said audio communication equipment from said first and second locations so that no interconnection path is provided between said encryption/decryption module and the non-selected audio communication equipment.