The modulation technique in the spread spectrum communication usually includes the process to modulate the carrier signal by means of ASK, PSK or FSK as the primary modulation, and then primary modulated signals are spread by the use of pseudo-noise(PN) code as the secondary modulation. In spread spectrum communication techniques, the PN code synchronization is a very important problem to establish the communication channels, so that a great many techniques has proposed concerned with it. In the case of digital data transmission system, a modulation technique which is called code modulation may be proposed in this paper. The modulation method include the procedure to multiply the PN code and data signal as the primary modulation, and then carrier signal is spread using that newly produced spread signal. The advantage of the code modulation is easy to establish the PN code synchronization. This paper describes on an experimental system using the circuit to process the carrier and the clock for PN code generator in phase. In conclusion, from results of the transmission test using its system, we found that our newly developed synchronization circuit is reliable for the spread spectrum communication system to transmit digital signals.
スペクトラム拡散通信方式における同期捕捉，保持に関する研究
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