基于GPS射频信号模拟的定时方法

针对采用GPS定时的设备提出了基于GPS射频信号模拟的定时方法，在不更改原有设备的情况下，可利用外部时间基准进行同步。首先建立卫星的轨道模型，模拟出卫星的导航电文；然后根据设备的位置模拟产生观测数据；再将导航电文调制到卫星的伪随机码上，根据观测数据计算出伪距，对调制的信号进行延迟；最后，通过正交射频调制得到GPS模拟信号。已建立的实验模型能实现以上模拟过程。测试表明，该方法可达到10ns级的定时精度。

Time Transfer Based on Simulated GPS RF Signal

A timing method based on simulated GPS RF signal is proposed for the GPS timing device. By using this method the device can be synchronized with external time without any change making of the original device. At first, the orbit model of GPS satellite is set up and the navigation message is simulated. Then the observation data can be calculated based on the position of device. The navigation data is modulated to the GPS pseudo random code. The pseudo range can be obtained from the observation data and the signal delay is taken into consideration. At last the simulated GPS signal is obtained through orthogonal RF modulation. The established prototype can realize the above simulation procedure and the experiment showed that the timing precision of 10 ns can be obtained by using this method.