Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via time channels
Reexamination Certificate
1998-05-14
2001-08-14
Kizou, Hassan (Department: 2738)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via time channels
C370S529000, C370S320000, C370S326000, C370S336000, C370S342000, C370S343000, C380S001000
Reexamination Certificate
active
06275509
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to using a single communications channel for multiple concurrent transmissions. More specifically, but without limitation thereto, the present invention relates to a device for combining concurrent communications signals in the same frequency band, transmitting the combined signal to a remote receiver, and separating the combined signal into replicas of the concurrent communications signals.
One of the problems facing the rapidly growing telecommunications industry is the high number of communications signals required to fit into a limited frequency bandwidth. It is also desirable in some applications to conceal the fact that a certain signal is being transmitted. One way to conceal a signal is to mask it with another signal in the same frequency band, but then the problem arises of recovering the masked signal without losing information due to the presence of the masking signal.
A continued need exists for a device that can combine concurrent communications signals into the same frequency channel to conserve the available bandwidth and be able to recover the signals without losing their information.
SUMMARY OF THE INVENTION
A masked signal transceiver of the present invention is directed to overcoming the problems described above, and may provide further related advantages. No embodiment of the present invention described herein shall preclude other embodiments or advantages that may exist or become obvious to those skilled in the art.
A masked signal transceiver of the present invention comprises a transmitter for transmitting a combined signal of a primary communications signal and an attenuated secondary communications signal occupying substantially the same frequency band concurrently. A receiver receives the combined signal and demodulates the primary communications signal to extract the primary communications signal information. An adaptive locally optimum processor separates the secondary communications signal from the combined signal. The secondary communications signal is then demodulated to extract the secondary communications signal information.
An advantage of the masked signal transceiver of the present invention is that two signals may be transmitted concurrently in the same frequency band, reducing the required bandwidth for multiple communications channels.
Another advantage is that the primary communications signal may be received and demodulated by an ordinary radio receiver, while the secondary signal may not, thereby providing a covert means of communication.
The features and advantages summarized above in addition to other aspects of the present invention will become more apparent from the description, presented in conjunction with the following drawings.
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Bond James W.
Schlosser Thomas W.
Fendelman Harvey
Kagan Michael A.
Kizou Hassan
The United States of America as represented by the Secretary of
Tran Thien
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