【作者】 张伟玉；

【导师】 张国雄；

【作者基本信息】 天津大学 ， 测试计量技术及仪器， 2013， 博士

【摘要】 工农业生产对产品质量的要求决定了对过程参数控制精度的要求越来越高，与实验室仪器仪表相比，现场仪器仪表特别是用于油井探边的高温高精度电子压力计更应结构简单、体积小、分辨率高、高温性能好。谐振式传感器被广泛地应用于现场仪器仪表上对力、压力、湿度、温度、角速度、加速度、位移、质量流量、气体成分进行测量和进行生物分子识别及磁场的检测。压电石英晶体压力温度传感器在探边用压力温度计上有其他传感器无法比拟的优势。谐振式传感器的零点输出具有一定的初始频率，范围为几kHz到几百kHz，测量参数引起的频率变化量比初始频率小很多。分辨率是精度的基础，怎样高分辨率测量有一定初始频率的小频率增量问题一直未能很好地解决。本文从高分辨率测量谐振式传感器输出信号入手，对小频率增量的测量方法、逻辑混（差）频器的输入输出特性、频率测量的方法及算法进行了深入研究，并取得以下创新成果：第一，提出了一种适合现场仪器仪表采用的高分辨率测量由待测参量引起的小频率增量的测量方法。第二，理论上研究了D触发器差频器的输入输出特性；提出了输入信号需要满足的条件，找出了产生测量误差的主要原因；提出了为减少误差，输入信号与D触发器的连接方式及参考信号的取值范围；通过对测量数据的有机取舍，得到了比较高的测量分辨率。第三，理论上研究了逻辑门混频器的混频特性，进行了归类，选出了作为混频器的最佳逻辑门；在此基础上，通过理论分析，提出了基于异或门，仅使用一阶RC滤波器、特性优良的差频电路，并通过实验验证了理论的正确性。第四，通过理论分析，提出了一种电路简单、测量分辨率高的连续计数间隔标记的频率测量方法及算法（标记法），并通过实验对理论进行了验证。第五，进行了谐振式传感器高分辨率测量方法的比较。使用D触发器对待测信号和参考信号进行差频，以D触发器输出信号的周期为闸门，连续对基准信号进行计数，得到测量数组，对测量数组中的数据进行有机取舍，能得到较高的测量分辨率且电路简单，可供使用谐振式传感器的现场仪器仪表使用；标记法的测量分辨率远远高于混（差）频法，在进行一定的技术实现方法完善后，有望成为一种电路简单、成本低、高分辨率的频率测量方法，应用前景相当广阔。标记法是本论文最主要的理论与实践创新。它优于间接法，因为间接法只利用整个测量时间内进入计数器的时钟脉冲数，根据它来确定待测频率；而标记法不仅利用整个测量时间内进入计数器的时钟脉冲数，而且利用每一小段时间进入计数器的时钟脉冲数变化所提供的信息，来共同确定待测频率。标记法优于回归法，是因为回归法主要利用进入计数器的时钟脉冲数的平均速度；而标记法充分利用在各个时段计数器的时钟脉冲数变化的细节，嵌套数越多，细节信息越丰富，标记法的优越性越明显。更多还原

【Abstract】 Compared with laboratory equipments, downhole probes for testing reservoirlimit should have the advantages of simple structure, small size, high resolution andexcellent high temperature performance.Resonator-based sensors are utilized in a wide range of applications in fieldinstruments. The resonant quartz crystal sensor is one of the most widely used in theoil field for testing reservoir limit.Resonator-based sensors output includes initial frequency and variation of thefrequency caused by the change of the measured parameter. The range of initialfrequency is several thousand to several hundred thousand Hz. The variation of thefrequency is much smaller than the initial frequency. The uncertainty ofmeasurement can never be smaller than its resolution. Measuring small frequencyincrements with high resolution remains a problem. In order to solve the problem,the measuring method of small frequency increments, the input and outputcharacteristics of logic mixers, the measuring method and processing algorithm offrequency are studied in this paper. The main contributions and innovation points areas follows:Firstly, a high resolution measuring method on small frequency increments forfield instruments was proposed.Secondly, the input and output characteristics of a D flip-flop mixer werestudied in theory. Its application conditions were given. The main reasons resultingin its output measurement errors were analyzed. The electric connection mode of theinput signal with D flip-flop and the range of reference signal value were putforward to reduce the measurement error. High measuring resolution has beenobtained through proper selection of measurement signals.Thirdly, the frequency mixing characteristics of logic gate mixers were studiedin theory and mixers were classified according to their mixing characteristics. TheXOR and XNOR mixers have better performances than the others. A new frequencysubtracting circuit based on XOR gates with a first-order RC filter was presentedand validated in experiments..Fourthly, based on the theoretical analysis and experimental validation, a highresolution frequency measurement method and algorithm, Continuous Counting andPeriod Marking with its shortened form Marking Method, was introduced.Finally, using the real sensor output, a comparison among several methods mentioned in this thesis was carried out. A D-type flip-flop mixer which receivestwo input signals of different frequencies forms an output signal whose frequency isequal to the frequency difference between these two input signals. Counting thenumber of rising or falling edges of a reference frequency within each cycle of the Dflip-flop mixer output, a measurement array is obtained. By selecting valid data fromarray and calculating, the frequency of the unknown signal can be obtained withhigh resolution. This method is very suitable for field instruments usingresonator-based sensor systems. The resolution of Marking Method is much higherthan other methods. With some further improvements; this method will be ahigh-resolution frequency measurement method with very broad applicationprospects.Marking method is the main creative contribution of this thesis. It is superior tomethod based of period measurement since the period measuring method paysattention only to the total number of pulses counted during certain period of time,where as the marking method takes into consideration also the numbers of pulsescounted during each individual short interval. Marking method is superior toregression method since the later one is based on calculation the average pulse rateper unit of time where as the marking method takes into account all the details ofpulse rate variations within the whole measuring time as well. The advantage ofthe marking method becomes even more significant when there are multiple loopsinvolved in the counting process.更多还原