| 摘要: |
| 中频相参雷达是一种通过在中频上的频率跟踪和相位补偿使不相参的回波具备相参性的雷达系统，这种雷达成本低、功率大，但是测速偏差和地物抑制能力相较全相参系统偏低，在实际使用中难以满足用户的需求。鉴于此，通过对中频相参数字接收机的频率跟踪和相位补偿功能的原理分析，推导出中频相参数字接收机经过相位补偿后，得到的回波的发射初始相位并不能修正到零，实际上存在两部分误差：第一部分与中频相参数字接收机内部数字控制振荡器（NCO）的频率、回波与样本脉冲之间的延时关系成正比，只要对NCO频率进行调整，此误差在脉间和距离上就是变化的；而第二部分是测频处理算法带来的误差。在发射样本信号频率变化不大的情况下，第一部分相位补偿误差在脉间的变化对多普勒速度处理的偏差、信号功率谱的展宽以及信噪比的下降起主导作用。在以上推论的基础上，改进了中频相参数字接收机的频率跟踪策略，有效改善了测速精度和地物抑制能力。 |
| 关键词: 中频相参雷达 相位补偿 数字接收机 地物抑制 |
| DOI：10.3969/j.issn.1672-2337.2018.02.015 |
| 分类号:TN957.5 |
| 基金项目: |
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| Analysis of Phase Compensation Error in Digital Receiver of Intermediate Frequency Coherent Radar |
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XU Penglai
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Anhui Sun-Create Electronics Corporation， Ltd， Hefei 230088， China
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| Abstract: |
| Intermediate frequency coherent radar is a radar system which changes the non-coherent echo into coherent in intermediate frequency digital receiver through frequency tracking and phase compensation. This radar has lower cost and larger transmitting power. Compared with coherent radar， however， it has larger speed deviation and lower ground clutter suppression ability. It is difficult to meet the users requirements. In view of this， through analyzing the principle of frequency tracking and phase compensation， it is found that the intermediate frequency coherent radar cannot fully correct the initial phase of echo through frequency tracking and phase compensation. There are two parts of the phase compensation error. The first part is proportional to the frequency of numerical control oscillator (NCO) in digital receiver and the delay relationship between the echo and the sample pulse. This error changes at the range and from pulse to pulse if the frequency of NCO is adjusted. The second part is brought by the frequency measurement algorithm. The pulse to pulse change of the first part error plays a dominant role in the Doppler velocity processing bias and the decrease of SNR. On the basis of the above deduction， an improved frequency tracking algorithm is proposed， which improves the Doppler velocity processing accuracy and ground clutter suppression ability effectively. |
| Key words: intermediate frequency coherent radar phase compensation digital receiver ground clutter suppression |
