• Progress in Superconductivity and Cryogenics
• /
• v.23 no.4
• /
• pp.56-60
• /
• 2021

The microwave Radar used for special purposes in the past is being applied in various areas due to the technological advancement and cost reduction, and is particularly applied to autonomous driving in the automobile field. The FMCW (Frequency Modulated Continuous Wave) Radar can acquire level information of liquid in vessel based on the beat frequency obtained by continuously transmitting and receiving signals by modulating the frequency over time. However, for cryogenic fluids with small impedance differences between liquid medium and gas medium, such as liquid nitrogen and liquid hydrogen, it is difficult to apply a typical Radar-based level meter. In this study, we develop an 80 GHz FMCW Radar for level measurement of cryogenic fluids with small impedance differences between media and analyze its characteristics. Here, because of the low intrinsic impedance difference, most of the transmitted signal passes through the liquid nitrogen interface and is reflected at the bottom of the vessel. To solve this problem, a radar measurement algorithm was designed to detect multiple targets and separate the distance signal to the bottom of the vessel in order to estimate the precise position on the liquid nitrogen interface. Thereafter, performance verification experiments were performed according to the liquid nitrogen level using the developed radar level meter.

• Journal of Satellite, Information and Communications
• /
• v.9 no.2
• /
• pp.38-44
• /
• 2014

This paper presents design of a FMCW (Frequency Modulated Continuous Wave) level meter as well as simulation result of the designed system. The system is designed to measure maximum range of 20m since FMCW radar can be used for measuring short range distance. The distance is measured by analyzing the beat signal which is generated as result of mixing transmitting signal with the reflected received signal. The Fast Fourier Transform is applied to analyze the beat signal for calculating the displacement and Zoom FFT technique is used to minimize measurement error as well as increase the resolution of the measurement. The resolution of the measurement of the designed system in this paper is 2.2mm and bandwidth of 1.024GHz is used for simulation. Thus the simulation results are analyzed and compared in various conditions in order to get a comprehensive idea of frequency resolution and displacement resolution.

• Korean Journal of Remote Sensing
• /
• v.34 no.3
• /
• pp.535-543
• /
• 2018

Recently, level meters have been associated with the safety and maintenance of industrial sites and require a wide measurement range. Generally, to ensure the measurement range of the level meter, the measurement environment is improved to reduce the noise or to compensate the distortion of the signal through signal processing. The noise of FMCW (Frequency Modulated Continuous Wave) radar level meter or the distortion of the signal affects the near region characteristics of the level gauge, resulting in a reduction of the minimum detection distance. In this paper, an equalizer filter considering characteristics of window function and bit spectrum is applied to remove the noise in the near region of the level meter to improve the minimum detection distance performance and to improve the measurement reliability in the vicinity of the level meter, which is relatively difficult to detect, we want to improve the detection range.

• Proceedings of the IEEK Conference
• /
• 1998.10a
• /
• pp.331-334
• /
• 1998

In this paper, we have presented an improved design of the microwave level meter based on the principle of FM-CW radar. First, we have analyzed the effect of VCO nonlinearity on the spectral broadening of the beat signal, and presented a new type of design theory to linearize VCO tuning curve adopting FFT algorithm. Simulation results for a VCO having the linearity of 25% have been presented, which show the usefulness of the design algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.24 no.1
• /
• pp.83-90
• /
• 2020

A commercial flow measurement radar sensor estimates a quantity of flowed water using surface flow rate. In this way, the amount of water flowing per unit time cannot be measured accurately because of using an estimation result and it can't response environmental changes. For more accurate flow measurements we need width of waterway, water level and distance that water moved per unit time. Commonly two sensors are used to measure water level and flow rate. In this paper, we propose a method to simultaneously measure the water level and surface flow velocity using a single FMCW radar sensor and design the transmission waveform. In order to verify the waveform design, received signal is modelled based on transmission waveform. In addition, we consider phenomenons and problems that may occur in signal processing.

• Progress in Superconductivity and Cryogenics
• /
• v.24 no.1
• /
• pp.29-33
• /
• 2022

Recently, development of a cryogenic fluids storage tank for storing or transporting liquid hydrogen is actively in progress. In cryogenic fluids storage tanks, hydrogen evaporates due to the extreme temperature difference inside and outside the tank. As the mass of the cryogenic fluids changes with continuous vaporization, the fluids level also changes. Therefore, there is need for a method of accurately measuring the level change in the storage tank. In the case of general cryogenic fluids, it is difficult to accurately measure the level because the dielectric constant is very low. As a method of measuring cryogenic fluids level with low dielectric constant, it can be used an Millimeter wave (MM wave) FMCW radar sensor. However, the signal sensitivity is very weak and the level accuracy is poor. In this paper, the signal sensitivity is improved by designing the horn lens antenna of the existing 80 GHz FMCW radar sensor. Horn lens antenna is fabricated by FDM/SLA type 3D printer according to horn and lens characteristics. The horn is used to increase the signal gain and the lens improves the signal straightness. This makes it possible to measure the level of cryogenic fluids with a low dielectric constant.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.10
• /
• pp.1964-1972
• /
• 2017

K-water have been operating as an International accredited calibration organization for ISO 17025 regarding float, ultrasonic and radar type since 2008. Due to the absence of on-site calibration system, water level meter could only be calibrated from a laboratory. Therefore K-water institute developed an mobile calibration system for water-level meter in 2015 to calibrate the water-level meter on site. The mobile calibration system was certificated by KOLAS(Korea Laboratory Accreditation Scheme) in 2016. In this paper a mobile calibration system, which is a method to calibrate float type water level meter on site, is established. A mathematical equation was derived by reviewing characteristics of standard equipment and measurement. By developing the mobile calibration system, it is possible to achieve reliability of data through scientific system operation on hydrological data.

• Korean Journal of Remote Sensing
• /
• v.35 no.3
• /
• pp.389-400
• /
• 2019

Level meters are non-invasively capable of measuring the level of the medium, and a growing variety of level meters are being used in the industry in connection with safety and maintenance. The level meter can be measured according to various kinds of medium such as solid medium such as coal, flour, rice and liquid medium such as water and petroleum. In order to reduce the error depending on the medium, the measurement using the Doppler Effect can compensate the measurement error, However, the number of signal processing steps is increased, the operation speed is further increased, the hardware complexity increases, and a high cost structure is required. In this paper, we propose a method to improve the signal processing operation structure of the remote measurement level meter to reduce the amount of computation and the resource usage of the required FPGA.

• Proceedings of the KIEE Conference
• /
• 2005.07d
• /
• pp.2492-2494
• /
• 2005

This study designed on the standard calibration facility for calibration about radar type, ultra-sonic type and floating type. We reviewed calibration facilities, analysis any problems, and proposed optimal plan which uses EDM and electrical level meter.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.1
• /
• pp.18-25
• /
• 2000

In this paper, we have designed a microwave level meter based on the FM-CW radar theory using a YIG-tuned oscillator (YTO). YTO has an excellent frequency linearity, so a linearizer circuit is not necessary for the level meter. It is shown that interference signals reflected from nearby obstacles can be removed by using a digital band-pass filter. An FIR band-pass filter is designed using the Kaiser window. The distance measurement has been performed in the outdoor test field. The measurement data have been obtained for the range of 1~40m with 1m step, and the results show that the standard deviation of the measured data is 2.33 cm. The level meter manufactured in this study can be applied usefully in the industrial facilities which are not accessible easily, for example, to measure the level of molten metal in the iron and steel company.