| 摘要 |
PURPOSE:To increase the change of detection of correlation on the receiving side and to shorten a synchronization confirmation time by applying redundancy to a false noise code of the longest code string at a degree preventing the randam property of a transmission side from damage. CONSTITUTION:On the transmission side, a false noise code generating circuit 3 forms a false noise code in the longest code string and a code string 30 obtained by shifting the former code by 1/2 at its phase and an exclusive OR23 switches said codes successively in each code period to form a code string 31 having the period of twice the original code period and transmit data as a spread spectrum wave SS on the basis of the code string 31. On the receiving side, the same false noise code 32 as that of the transmission side and a code string 23 phase-shifted by 1/2 the code period are inputted to two delay circuits 28, i.e. 1/2-bit and 1-bit delay circuits, and two code strings each of which consists of three kinds of codes are outputted from the circuits 28, properly selected by a switch circuit 29 and sent to three correlators 7-9. A synchronization detecting circuit 26 detects respective correlator output signals and also controls a clock signal control circuit 19 and a code string switching circuit 29 on the basis of output signals from pattern detectors 21, 25 outputting certain patterns in each code string period of a false noise code generating circuit 20. |
