|
| US3939419 | 6 Nov 1956 | 17 Feb 1976 | The United States of America as represented by the Secretary of the Army | Security remote control method and system |
| US3991273 | 4 Oct 1943 | 9 Nov 1976 | Bell Telephone Laboratories, Incorporated | Speech component coded multiplex carrier wave transmission |
| US4802220 | 20 Mar 1985 | 31 Jan 1989 | American Telephone and Telegraph Company, AT&T Bell Laboratories | Method and apparatus for multi-channel communication security |
