| 摘要 |
PROBLEM TO BE SOLVED: To provide a technique for furthermore increasing the secrecy of a spread spectrum system. SOLUTION: A serial digital signal S1 is made signals corresponding to a signal I and a signal Q by an IQ separation circuit 1, and a spread code generation circuit 6a, etc., and multiplication circuits 2a and 2b generate spread spectrum signals for each signal. The signal is mounted on a carrier wave by multiplication circuits 3a and 3b and transmitted toward a receiving part. At the receiving part, a local oscillation frequency generated by a local oscillation circuit 169 and a frequency obtained by shifting its phase by 90 deg. by a phase shifter circuit 18 are multiplied by multiplication circuits 12a and 12b to be demodulated and spread codes from a spread code generation circuit 16a generating the same spread code with a transmission part are mutually multiplied again by the multiplication circuit 12a and 12b to be spread inversely to fetch signals corresponding to the original signals I and Q. The signal is decoded by an IQ composing circuit 11 to obtain a reception signal S2 being an original serial-digital signal. The communication is performed by switching plural spread codes. |
