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设计了一种供1975年“海盗”轨道飞行器指令系统用的简单的数字式二阶锁相环。这种锁相环除了数字-模拟变换器外,只有一个加法——减法器.两个寄存器和一个可被控制逻辑电路修正的计数器。这种锁相环仅须测量相位误差的极性并根据过滤后的信号序列的极性来修正系统的钟信号。这种锁相环对输入信号的增益变化不敏感,因此它具有性能长期稳定的优点。由于锁相环捕获的可靠性极高,因此予期的性能可得到保证,然而,相对于模拟环路而言,在稳态条件下,这种环路的性能仅略有减低。在下文的捕获特性和稳态相位误差各节中,给出予计的分析数据和实验结果。
A simple digital second-order phase-locked loop was designed for the 1975 Pirate orbiter command system. This phase-locked loop in addition to digital-analog converter, there is only one addition - subtracter. Two registers and a control logic circuit can be modified counter. This phase-locked loop only needs to measure the polarity of the phase error and correct the system’s clock signal based on the polarity of the filtered signal sequence. This phase-locked loop is insensitive to gain variations of the input signal, so it has the advantage of long-term, stable performance. Due to the high reliability of phase-locked loop capture, the expected performance is guaranteed, however, the performance of this loop is only marginally reduced at steady-state conditions over analog loops. In the sections below for capture characteristics and steady-state phase errors, the expected analytical data and experimental results are given.