| 摘要 |
<p>PURPOSE:To attain data transmission at a high speed by synchronizing a PN code for spread spectrum modulation with a digital data to be sent. CONSTITUTION:An A/D converter 3 samples a voice signal according to a prescribed sampling clock, converts a sampled analog amplitude into a digital data and outputs serially bit by bit according to a prescribed data transmission clock. An FSK modulation signal is fed to one input terminal of a double balanced modulator 7. A prescribed PN code signal is fed from a PN code generator 9 to the other input terminal of the double balanced modulator 7. Thus, an output signal of the FSK modulator 5 is subject to spread spectrum modulation, an undesired band component is eliminated by a filter 11, then the resulting signal is sent from a transmission antenna 23.</p> |
