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在雷达和电子战所用的接收机中,通常都是在时域里测量信号的频率,一般的测量方法是在系统的参考振荡源所规定的一个周期内对输入信号进行过零点计数.然而,信号源的相位噪声会产生时城计算误差,需要利用阿伦方差(AV)测量来对系统精度数量上加以表示.AV测量系统包含有比待测系统更低相位噪声电平的信号源.在确定测试系统的精度时存在一个难题,因为在这些系统中优异的低相位噪声信号源排除了使用另一个具有更低相位噪声源的AV测量系统.庆幸的是有一些测量技术可用来预测AV测量系统的精度,从而消除了对被测系统的影响.
In radar and electronic warfare receivers, the frequency of the signal is usually measured in the time domain. The usual method of measurement is to count the zero crossing of the input signal during one cycle specified by the system’s reference oscillator. However, The phase noise of the signal source can have a time-to-city calculation error and the amount of system accuracy needs to be represented using an Avon variance (AV) measurement. The AV measurement system contains a source of lower phase noise level than the system under test. There is a challenge in determining the accuracy of the test system because an excellent source of low phase noise in these systems precludes the use of another AV measurement system with a lower phase noise source.However, there are some measurement techniques that can be used to predict AV measurements System accuracy, thus eliminating the impact on the system under test.