Comparative research of quality indicators of measuring instruments: practical aspects

The main purpose of modern measuring instrument MI is to perform accurate and reliable measurements in order to obtain complete and reliable measurement information. The MI must be of proper quality, which must be reliably assessed. For technical means, traditional quality indicators have been established, some of which are common to MI. The metrological characteristic is unique to a MI and can be considered one of the most important of MI indicators. The quality of MI is characterized by a certain system of quality indicators. Depending on MI group, the system of quality indicators can differ. The target indicators are specific for each type of product. These indicators require additional analysis. The main metrological characteristics should be referred to the target indicators of MI. For some MI categories, additional indicators can be established, and for others, they are excluded. The methodology of evaluation of MI quality indicators and algorithm of its realization are offered. The digital multimeters as category of MI have been selected for practical comparative evaluation of MI quality indicators. The ten indicators for this category of MI have been refined. Comparative expert evaluation of quality indicators of 12 multimeters was carried out with the involvement of a group of 34 metrology experts. The weight of each of the 10 selected MI quality indicators was determined. The results of expert evaluation of multimeter are presented.

Lock-in amplifier with a high common-mode rejection ratio in the range of 0.02 to 100 kHz

<span lang="EN-US">The paper presents a new lock-in amplifier with a differential input. The lock-in amplifier has a high common-mode rejection ratio of 200 dB at 1 kHz and 160 dB in the frequency range of 20 Hz to 100 kHz. A method for extending the dynamic range of comparing signals is suggested. The experimental results of metrological characteristic tests are discussed.</span>

Research on Metrological Characteristic of Micro-Differential Pressure Sensor in Draw Resistance Device

Micro-differential pressure sensor is one of the core components in the draw resistance device. Its metrological characteristic directly affects the accuracy of cigarettes’ draw resistance. Because different principles of micro-differential pressure sensors are used by each equipment manufacturer, the influences are not consistent on measuring the draw resistance. In order to study the influences of micro-differential pressure sensor on the draw resistance measurement, we will analyze its metrological characteristic through the acquisition of the output voltages under the different standard pressures. The experimental results show that the precision level of micro-differential pressure sensor using is higher, and it has little effect on the draw resistance measurement.