Covert communication system
US4607375A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 17, 1984 |
| Grant date | Aug 19, 1986 |
| Priority date | — |
| Expiry date | Oct 17, 2004 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/69
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
The covert communication system comprises a first arrangement to translate binary "1" bits into different portions of a predetermined PN (pseudonoise) code sequence and primary "0" bits into a complement of the different portion of the PN sequences, the PN sequence being selected to spread the binary signal over as large a bandwidth as possible. A second arrangement is coupled to the first arrangement to transmit the portions of the PN sequence and the complements of the portions of the PN sequence at a variable transmission rate and at a power level below environmental noise of propagation medium. A third arrangement is coupled to the second arrangement through the propagation medium to receive the portions of the PN sequence and the complements of the portions of the PN sequence imbedded the environmental noise with a fourth arrangement coupled to the third arrangement to recover the binary signal from the received portions of the PN sequence and the received complements of the portions of the PN sequence. To render the communication system more covert, the second arrangement includes the Rayleigh fader producing a waveform simulating a Rayleigh fading characteristic with the wav…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.