| 摘要 |
The transmitter installed at the moving objective generates and sends the high frequency for indicating the present position to the central station. The method uses the the expanded high frequency in certain band by modulating the psudo noise signal two times so that the frequency interference is prevented. The transmitter includes mixers (21,52) mixing the high frequency to the local oscillation frequency and providing to an intermediate amplifier (22), a demodulator (23) demodulating the intermediate frequency to separate the code signal and the carrier wave signal, PLLS (26,27) comparing the local oscillation frequency to the amplified intermediate frequency, and a voltage controlled oscillators (24,25) generating the local oscillation frequency being same to the carrier wave frequency. |
