• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.11
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• pp.857-867
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• 2018

Active array radar is evolving into digital active array radar. Digital active array radar has many advantages for making several simultaneous radar beams from the digital receive data of each element. A digital-type transceiver(TR) module is suitable for this goal in radar. In this work, the design results of an L-band digital TR module are presented to verify the possibility of fabrication for a digital active array antenna. This L-band digital TR module consists of a gallium-nitride-type HPA to achieve a more than 350-W peak output power and one-chip transceivers that include a digital waveform generator and analog digital converter. The receiving gain was 47 dB, the noise figure was less than 2 dB, and the final output type of the four channel receiving paths was one optic signal.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.2
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• pp.151-159
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• 2022

In this paper, we implement a digital multi-beamformer using FPGA(Field Programmable Gate Array) which has advantages in parallel and real-time data processing. This is accomplished through the use of not only high-speed data communication but also multiple beam forming, which is currently required by MFR(Multi Function Radar). As a result, the beamformer can process 24 Gbps throughput in real-time and form 5 digital beams at the same time. It is also compared to the results of Matlab simulations. We demonstrate how an implemented beamformer can be used in an MFR system by using a digital array antenna.

• ETRI Journal
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• v.32 no.5
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• pp.827-830
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• 2010

For an adaptive cruise control (ACC) stop-and-go system in automotive applications, three radar sensors are needed because two 24 GHz short range radars are used for object detection in an adjacent lane, and one 77 GHz long-range radar is used for object detection in the center lane. In this letter, we propose a single sensor-based 24 GHz radar with a detection capability of up to 150 m and ${\pm}30^{\circ}$ for an ACC stop-and-go system. The developed radar is highly integrated with a high gain patch antenna, four channel receivers with GaAs RF ICs, and back-end processing board with subspace based digital beam forming algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.3
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• pp.371-379
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• 2011

Active phased array antenna structure is used for modern multi-function radars. To search targets in high clutter environment, the radar receiver needs high dynamic range performance. Though active phased array antenna structure lead to increase of SNR, the SFDR is not increased. In this paper, high SFDR receiver of X-band active phased array radar was designed and manufactured. One channel digital receiver is connected to 32 T/R modules and one PCB assembly is composed to 2 channel digital receivers with RF part, ADC part, LO distribution part and digital down conversion part. A commercial FIFO board was used for digital receiver measurement about major performance in digital output signal condition. The measured digital receiver gain and SFDR is 33 dB and more than 81 dBc each.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.12
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• pp.2628-2635
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• 2010

This paper analyzes the detection probability of FMCW (Frequency Modulated Continuous Wave) radar based on Doppler frequency and analog-digital converter bit and designs and implements signal processing part of FMCW radar. For performance evaluation, the FMCW radar system consists of a transmitted part and a received part and uses AWGN channel. The system model is verified through analysis and simulation. Frequency offset occurs in the received part caused by the mismatching between the received signal and the reference signal. In case of Doppler frequency less than about 38KHz, performance degradation of detection does not occur in FMCW radar with 75cm resolution The analog-digital converter needs at least 6 bit in order not to degrade the detection probability. And, we design and implement digital signal processing part based on DDS chip of digital transmitted signal generator for FMCW radar.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.3
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• pp.497-502
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• 2018

An analog to digital converter(: ADC) has been designed to extract video signals of marine X-band radar and convert to digital signals in order to produce rainfall information. X-band weather radars are suitable for high temporal-spatial resolution observations of rainfall over local ranges but they are very expensive and require professional management. The marine radars with 10-2 cost facilitate data collection and management as well as economic benefits. To validate the usefulness of the developed ADC, comparative observations were made with weather radar for short term precipitation cases. The rainfall distribution of marine radar observations are consistent with that of weather radar within a radius of 15 km. This demonstrates the usability of marine radar for rainfall observations.

• Korean Journal of Remote Sensing
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• v.37 no.5_1
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• pp.1043-1059
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• 2021

Forest and agricultural land are very important factors in the environmental ecosystem and securing food resources. Forest and agricultural land should be monitored regularly. CAS500-4 data are expected to be effectively used as a supplement of monitoring forest and agricultural land. Prior to the launch of the CAS500-4, the relative canopy height error analysis of the digital elevation model on South Korea was performed to determine the vertical target accuracy. Especially, by considering area of interest of the CAS500-4 (mountainous or agricultural area), it is conducted that vertical error analysis according to the slope and canopy. For Gongju, Jeju, and Samcheok, the average root mean squared differences were calculated compared to the drone LiDAR digitalsurface models, which were filmed in autumn and winter and the 5 m digital elevation model from the National Geographic Information Institute. As a result, the Shuttle radar topography mission digital elevation model showed a root mean squared differences of about 8.35, 8.19, and 7.49 m, respectively, while the Copernicus digital elevation model showed a root mean squared differences of about 5.65, 6.73, and 7.39 m, respectively. In addition, the root mean squared difference of shuttle radar topography mission digital elevation model and the Copernicus digital elevation model according to the slope angle were estimated on South Korea compared to the 5 m digital elevation model from the National Geographic Information Institute. At the slope angle of between 0° to 5°, root mean squared differences of the Shuttle radar topography mission digital elevation model and the Copernicus digital elevation model showed 3.62 and 2.52 m, respectively. On the other hands root mean squared differences of the Shuttle radar topography mission digital elevation model and the Copernicus digital elevation model respectively showed about 10.16 and 11.62 m at the slope angle of 35° or higher.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.4
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• pp.132-137
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• 2007

The dynamic range of the radar which uses digital signal processors is limited by ADC(Analog-to-Digital Converter). That parameter and ADC loss depend on the noise level of radar receiver. In order to stabilize the performance of radar systems, it is necessary to maintain the noise level constantly. This paper presents the noise AGC(Automatic Gain Control) concept that can keep the noise level constantly and proves that the concept is acceptable through the hardware test and evaluation.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.484-489
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• 2002

This paper concerns the design and implementation of a Bandwidth Variable Digital Chirp Generator (DCG) for the radar altimeter. A double SRAM parallel structure is used to breakthrough the upper DCG bandwidth limited by the highest clock frequency of the digital chips. An experimental system working in the waveform storage method has been implemented. We show that the bandwidth changed according to the radar altimeter's requirement and the design released the stringent speed requirement of the chips fur making a variable wide bandwidth DCG.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1090-1097
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• 2007

The multibeam surveillance radar is a state-of art of 3D radar technology. It applies the stacked beam-on-received realized by a digital beamformer. In this paper, a design concept of beamformer and a method of target altitude extraction for multibeam surveillance radar in the normal environmental condition considering no multipath situations are proposed and investigated. The extraction algorithm based on antenna sine space coordinated system in a FFT digital beamformer is described. The proposed algorithm is simulated by 1 look-up table data and confirmed to have consistent results in accordance with a variety of target altitudes and a full radar frequency range.