| 摘要 |
PURPOSE:To attain data transmission in an absolute phase modulation system by transmitting a modulation wave which is obtained by means of periodically inserting a non-modulated part into a phase modulated wave obtained by making transmission data into a frame and extracting the non-molduated part from a reception wave on a reception side. CONSTITUTION:A modulator 2 phase-modulates a code which is made into the frame in a non-modulated code F that is periodically inserted into transmission data Dr on a transmission side 1 and transmits it. On the other hand, the reception side demodulates the transmission modulation wave Rf in a demodulator 3 and a frame synchronization circuit 4 synchronizes the demodulation data by the non-modulated part F and outputs reception data DR which has been frame-synchronized to outside. The reception modulation wave Rf is sampled by the pulse PF of frame synchronization in a switch 5 so as to extract a non-modulated wave RfF. A filter 6 extracts the non-modulated wave RfF and a reference carrier C for demodulation is obtained, whereby it is supplied to the demodulator 3. Thus, a non-linear processing can be removed from the encoding processing of the reception wave, and data transmission in the absolute phase modulation system without differential modulation can be executed. |
