| 摘要 |
PURPOSE:To discriminate the synchronization in a surer way by using a noise squelch circuit as a correlation device for a spread signal. CONSTITUTION:Information 1 is modulated by an FSK modulator 2 in a transmission section 9 and subjected to spread modulation in a spread modulator 7 by using a spread signal being an output of a sender side spread signal generator 3 and sent. After the signal passes through a spread demodulator 8 in a reception section 10, the result is converted into a base band subject to frequency discrimination by an FSK demodulator 6 via a BPF 12. Then through the use of the principle that the output is reduced when a noise level of an out-band of the base band meets the spread synchronization, a noise squelch circuit 4 is used and the phase of the spread signal being the output of a receiver side spread signal generator 11 is controlled by a synchronizing circuit 6 so as to minimize the output thereby attaining synchronization detection and synchronizing tracking. Then the original information 1 is obtained by using a demodulator 5. |
