利用对比度最优准则的压控振荡器调频非线性误差估计与校正方法

针对压控振荡器调频非线性误差的准确估计与校正问题，提出一种以一维距离像对比度最优为准则的自适应估计与校正方法。本方法建立引入温度变量的压控振荡器频率特性模型，并据此估计出某一温度值对应的调频非线性误差，在对中频回波进行误差补偿和一维脉压后，以一维距离像的对比度最优作为迭代收敛准则，实现调频非线性误差的最优估计与校正。仿真和实测数据结果表明，该方法充分考虑了温度因素对压控振荡器输出频率的影响，能够在不增加硬件复杂度的前提下，通过算法实现对调频非线性误差的估计、跟踪与补偿。与传统基于硬件电路进行估计或校正的方法相比，新方法无需由硬件组成闭环估计通道，且具有实时性强、运算量小、补偿精度高的优点，对于克服实际工程应用中压控振荡器器件的参数漂移问题具有重要指导意义。
In order to accurately estimate and correct the frequency nonlinearity of voltage controlled oscillator, a novel approach based on contrast optimization of range profiles is proposed, which will perform nonlinearity estimation and correction adaptively. A temperature-varying tuning model is established in the proposed method, the nonlinearity is obtained with a given temperature by using this model. The nonlinearity is removed from the beat signal, and the range profiles of targets are derived by pulse compression. According to the contrast of range profile, the real temperature is iteratively estimated. The contrast of range profile will converge toward the maximum, so an optimal estimation of temperature, which is nonlinearity, is achieved. Simulation and experimental results show that the proposed approach with consideration on environmental temperature variation can estimate and correct the nonlinearity without any additional hardware circuit. Compared with the conventional approaches, this method can not only accurately estimate and track the frequency nonlinearity of voltage controlled oscillator in real time, but also has low hardware complexity and computing cost, which is the significant to solve the problem of voltage controlled oscillator frequency drift.