| 摘要 |
PROBLEM TO BE SOLVED: To make a system small in its scale and to reduce the cost of the system by spreading a data signal with a pseudo noise PN signal so as to reduce a power spectrum density of a carrier frequency and adding the carrier to a transmission signal so as to reduce required processing of a receiver side. SOLUTION: At a transmitter side, a multiplier 2 multiplies a data signal of a data signal source 1 with a PN signal from a PN signal generator 3 to spread the data signal. A PN signal whose DC component is 0 and whose low frequency component is less is selected. The spread signal is multiplied with a carrier from a local oscillator 5 at a multiplier 4 and the product is added to the carrier from the local oscillator 5 at a synthesizer 7. At a receiver side, a band pass filter 32 extracts only a carrier component from the signal received by a reception antenna 21 and the extracted component is multiplied with the received signal by a multiplier 33 to demodulate the received signal. An output signal from the multiplier 33 is binarized digitally in a comparator 34 and inverse spread processing is conducted in a digital circuit 30, from which a demodulated data signal 31 is extracted. |
