| 摘要 |
PURPOSE:To discriminate the synchronization establishment by using an FSK MODEM even in the case of forming a new communication system and using a carrier detector output of the MODEM so as to share part of the search control function. CONSTITUTION:A search control circuit 25 outputs a control signal to deviate a phase of a pseudo noise code by one bit to a pseudo noise generator 23, that is, outputs the control signal to deviate the phase of the pseudo noise code till a carrier detector output CD reaches a high level. On the other hand, when a phase of the pseudo noise code superimposed on a reception signal and a phase of the pseudo noise code fed from the pseudo noise code generator 23 are synchronized with each other, the correlation is taken, resulting that an output of a multiplier 22 rises up to 0dBm, then the output CD of the MO DEM 24 goes to a high level. The circuit 25 receiving the signal CD outputs a control signal to the pseudo noise code generating circuit 23 of the next stage so as to fix the phase of the pseudo noise code and the signal subjected to inverse spread modulation is FSK-demodulated in the MODEM 24 and a data is reproduced. |
