含氮物质检测系统脉冲发射源及控制模块的研制

发布时间：2018-08-27 10:03

【摘要】：通过检测含氮物质中14N原子核的核四极矩共振谱线,可以识别炸药的存在。每一种含氮化合物组成的炸药,都有各自对应的共振频谱,这些频谱相当于“指纹”,是唯一的。基于这一特性,本文结合项目课题,研制核四极矩炸药检测原理样机中的信号源、功率放大器及控制脉冲模块。本文首先介绍了核四极矩共振的基本原理、激励方式以及核四极矩共振检测系统的总体方案。其次针对核四极矩共振实际应用频率,基于DDS技术设计了核四极矩共振检测系统的射频信号源及控制电路。在介绍DDS基本架构、工作原理、优缺点的基础上、针对系统所需射频脉冲的指标要求进行了DDS部分的软硬件电路设计与实现。为满足核四极矩共振检测系统对发射功率的需要,在比较各类功率放大器性能特点的基础上,给出了采用AB类功率放大器来实现功率放大的电路方案,并采用负载牵引技术完成放大器阻抗匹配网络的设计,由于时间的原因,并未完成功放的硬件实现。最后对整个检测系统的信号源和脉冲模块进行了实物制作与调试。测试结果如下:(1)信号源可以输出3.41MHz、4.64MHz、5.1938MHz这3个频点信号,输出功率大于10dBm,对二次谐波的抑制有28dBc。(2)FID脉冲序列中90°脉冲宽度50us~85us,步进5us;激励脉冲间隔周期50ms~800ms,步进50ms。SE脉冲序列中0°脉冲宽度50us~85us,步进5us;重新聚焦脉冲宽度150us~290us,步进20us,都已经通过脉冲控制模块实现。输出电平大于3.3V。测试结果表明,所设计的模块基本达到预期要求。
[Abstract]:The existence of explosives can be recognized by detecting the resonance lines of the nuclear quadrupole moment of the 14N nucleus in nitrogen-containing materials. Each nitrogen-containing explosive has its own resonance spectrum, which corresponds to a fingerprint and is unique. Based on this characteristic, the signal source, power amplifier and control pulse module of nuclear quadrupole moment explosive detection principle prototype are developed in this paper. This paper first introduces the basic principle of nuclear quadrupole resonance, the excitation mode and the overall scheme of nuclear quadrupole resonance detection system. Secondly, according to the practical application frequency of nuclear quadrupole resonance, the radio frequency signal source and control circuit of nuclear quadrupole moment resonance detection system are designed based on DDS technology. On the basis of introducing the basic structure, working principle, advantages and disadvantages of DDS, the hardware and software circuit of DDS is designed and implemented according to the requirement of RF pulse in the system. In order to meet the need of transmitting power of nuclear quadrupole moment resonance detecting system, the circuit scheme of AB type power amplifier to realize power amplifier is presented on the basis of comparing the characteristics of various power amplifiers. The load traction technology is used to design the impedance matching network of the amplifier, but the hardware implementation of the amplifier is not completed because of the time. Finally, the signal source and pulse module of the whole detection system are made and debugged. The test results are as follows: (1) the signal source can output 3.41 MHz / 4.64MHz / 5.1938MHz signal. The output power is more than 10dBm, and the second harmonic suppression is 28dBc. (2) in the FID pulse sequence, the width of 90 掳pulse is 50usn 85us, the step is 5us. the interval period is 50ms / 800ms, the width of 0 掳pulse in the step 50ms.SE pulse sequence is 50usn 85usand the step is 5us. the width of refocus pulse is 150us-290us. step 20us. Has been implemented through the pulse control module. The output level is more than 3.3 V. The test results show that the designed module basically meets the expected requirements.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ560.7;TN78

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