High-T _c radio-frequency (rf) superconducting quantum interference devices are well understood and widely used in many areas of low-field measurement because of their high sensitivity and high resolution. Harmonic analysis has proven to be an efficient way for finding the optimum working point. However, there is a precondition for using harmonic analysis, which is not well understood so far. In this article, it is shown that the precondition can be fulfilled in the typical range of parameters and under our experimental conditions by using a direct mathematical derivation. It is demonstrated that the improvement of wavelet analysis in mean square error (MSE) is more than 50% for harmonic analysis. In addition, identification by forgetting factor recursive least square is a helpful way for self-tuning controller who gives fast tracking, small MSE and high coefficient of determination (R ² ) for harmonic analysis of different experimentally measured signals.

中文翻译：

---

高Tc射频SQUID小波分析与辨识相结合的谐波分析与自整定控制

高-T _{C ^}射频（rf）超导量子干涉装置因其高灵敏度和高分辨率而广为人知并广泛应用于低场测量的许多领域。谐波分析已被证明是寻找最佳工作点的有效方法。但是，使用谐波分析有一个前提条件，目前还不是很清楚。在本文中，通过使用直接的数学推导，表明可以在典型的参数范围内和我们的实验条件下满足先决条件。结果表明，对于谐波分析，小波分析在均方误差（MSE）方面的改进超过50%。此外，通过遗忘因子递归最小二乘法进行识别对于提供快速跟踪的自调整控制器是一种有用的方法， ² ) 用于不同实验测量信号的谐波分析。