| 摘要 |
PURPOSE:To simplify the constitution of a receiving device and to shorten the synchronism acquiring time for the receiving device applying a spread spectrum communication system using the hopping of frequency, by shifting the phase of the PN code obtained when the synchronism is acquired in a shorter time than the period of the PN code of the transmitter side. CONSTITUTION:A clock generator 3 of a frequency hopping receiver produces the clock to generate a pseudo random (PN) code. The phase of this clock is slid through a clock phase sliding circuit 4 and in a period shorter than the PN code of a transmitter. The output of the circuit 4 is exchanged with the clock of the generator 3 by a changeover switch 12 and with the output of a synchronism detecting circuit 11. Then the PN code corresponding to the output of the switch 12 is generated from a pattern generator 5. A frequency pattern corresponding to the PN code is generated in time series from a frequency synthesizing circuit 6 and mixed with the received signal by a mixer 7. Then the integration value of the signal detected by an envelope curve wave detector 8 is compared with the prescribed threshold value through the circuit 11. Then the switch 12 is switched to shorten the synchronism acquiring time. |
