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頻率合成器是原子頻率标准器,頻率測定仪中必不可少的部件。合成器大体上可分为同步振蕩器式和混合式两种,它們都是被其本身的杂散頻率噪声所調頻(調相)的。因此,研究这种信号的頻率稳定度,可知它与合連續頻譜的噪声情况是不同的。也就是說,頻率稳定度不仅与噪声电平和平均测定时間有关,而且与調制頻率、比較信号的頻差以及它們之間的相互关系有关。所以,仅用以往的測量方法,不可能得到正确的頻率稳定度。作为一种方法,有人提出用頻譜分析仪来测量噪声电子以得出頻率隐定度的最大值。現在,为获得标准器所需的頻率稳定度,其噪声比至少应为-80分貝(在10兆赫頻率上)。最后,进行了驗証性試驗,而且,制造了簡单的高精度頻率測量用合成器,得到了所期望的性能。
Frequency synthesizer is an atomic frequency standard device, an essential part of the frequency analyzer. Synthesizers can be roughly divided into synchronous oscillator type and hybrid type, both of them are frequency modulated by their own spurious frequency noise (phase modulation). Therefore, studying the frequency stability of this signal shows that it is different from that of a continuous spectrum. That is to say, the frequency stability is not only related to the noise level and the average measurement time, but also to the modulation frequency, the frequency difference of the comparison signal and their interrelationship. Therefore, it is impossible to obtain the correct frequency stability with only the conventional measurement method. As a method, it has been proposed to use a spectrum analyzer to measure the noise electrons to arrive at the maximum value of the frequency steepness. The noise ratio should now be at least -80 dB (at 10 MHz) to achieve the required frequency stability of the standard. Finally, a confirmatory test was conducted and, in addition, a simple synthesizer for high-precision frequency measurement was manufactured and the desired performance was obtained.