高精度同步输出多功能发射控制技术

Multifunctional transmitter control technology with high-precision synchronization output

针对现有的电磁探测发射控制系统输出同步精度低、输出信号存在累积误差等不足,提出高精度同步输出发射控制技术。设计以GPS自带时钟源和高精度恒温晶振协同作为系统时钟,结合各自的优点,在GPS同步时,由GPS自带时钟源信号作为系统时钟;在GPS无法同步时,利用GPS秒脉冲信号对恒温晶振输出的分频信号进行同步校正作为系统时钟;根据发射频点的特点,选择合理的校正周期,采用最小公倍数法对输出信号进行同步校正,减少输出频率的误差。研究结果表明:输出同步精度可以达到100 ns级,满足20 mrad以内的相位测量精度要求。利用FPGA强大的计数和分频功能,实现输出波形和频率的多样化。该技术可实现扫频和手动2种发射模式,输出满足频率域电磁探测和时间域电磁探测的多种波形,可扩展性强,同步精度高,满足多功能电磁探测发射系统的控制要求。

In view of the deficiencies of the low-synchronization precision and the presence of accumulated errors of the output signal for the transmitter control system of electromagnetic detection, the multifunctional transmitter control technology with high-precision synchronization output was proposed. The GPS built-in clock source cooperated with the high-precision oven controlled crystal oscillator（OCXO） as the system clock by adopting their respective advantages. When the GPS signal could be received, the GPS built-in clock source signal was the system clock; Otherwise, the second pulse signal of the GPS was used to synchronously calibrate the output frequency division signal of the OCOX to provide the system clock. According to the characteristics of the transmitting frequencies, a reasonable calibration period together with the method of least common multiple was adopted to synchronously calibrate the output signal, so as to reduce the error of the output frequency. The results show that the output synchronization precision can reach hundred-nanosecond level, meeting the required phase precision within 20 mrad. Using the powerful counting and frequency division functions of FPGA can achieve the diversification of the output waveforms and frequencies. This design can choose either the frequency sweep mode or the manual transmitting mode with different waveforms, meeting the requirements of both frequency domain and time domain electromagnetic detection, which can satisfy the demands of multi-functional electromagnetic detection transmitter control system.