• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.6
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• pp.808-815
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• 2015

For performance improving of C-band radar altimeter used in a missile system, Ku-band radar altimeter is developed. To utilize the time delay devices which are used in testing C-band radar altimeter, we proposed C-band and Ku-band frequency conversion method and implemented it as a part of missile system test equipment. In this paper we present design contents, development results and test application results of radar altimeter test equipments.

• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.174-179
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• 1998

In this paper, the radar altimeter for topographic mapping over land is introduced and the characteristics of the return signals are analyzed. The radar system is described briefly and the requirements to get the fine resolution of the terrain surface height are considered. The designed radar altimeter was tested on the landscape in the near of Stuttgart. The measured data shows very fine profile of the test landscape and the height errors induced from different geometrical structure of the land surface are acquired in the measurement. In the test area, most characteristics of radar return signals over land could be tested and the results of the topographic mapping using our radar altimeter can be used for future radar altimeter development for land applications.

• Korean Journal of Remote Sensing
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• v.29 no.1
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• pp.81-94
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• 2013

The Radar altimeter transmits radio signals to the surface, receives the backscattered signals and measures the distance between the airplane and the nadir surface. The measurements of radar altimeter are affected by various factors on the surface below the aircraft. This study performed flight campaigns in June 2012 and acquired raw data from radar altimeter, LiDAR and other sensors. Based on the LiDAR DSM (Digital Surface Model) as a reference data, the characteristics of radar altimeter were analyzed in the respect of range and surface area affecting on the receiving power of the radar altimeter. Consequently, the radar altimeter was strongly affected by the surface area within beam width and reflectivity related to RCS (Radar Cross Section) rather than range.

• Proceedings of the KSRS Conference
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• v.1
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• pp.135-137
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• 2006

HY-2, the China's satellite for oceanic dynamic environment measurement, is planed to be launched around 2010. The main payloads of HY-2 include a dual-frequency radar altimeter equipped with a three-band nadir-looking radiometer for atmospheric delay correction, a Ku-band radar scatterometer, and a five-band scanning radiometer. This presentation outlines the specifications, parameters, and design of the HY-2 radar altimeter and scatterometer.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.2
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• pp.258-261
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• 2012

Helicopter-borne FMCW radar altimeter obtains the altitude information using the beat frequency between the transmitted and reflected signal from the nadir direction. However, the altitude error may exist when the strong echoes are received from the large RCS at the off-nadir direction because of the wide beamwidth of the altimeter antenna. In this paper, in order to investigate the effect of the altitude error due to the large RCS around the off-nadir direction, the reflected signals were measured by using the corner reflectors displaced on the several reference ground positions, and the acquired signals were analyzed and compared in the spectral domain. The analysis results can be used for the improvement of the altitude accuracy in the radar altimeter.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.2
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• pp.147-155
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• 2016

This paper presents a jamming detection and suppression algorithm of a frequency-modulated continuous-wave(FMCW) radar altimeter. The radar altimeter measures the noise level at the noise measuring period before the transmitting and receiving period and finds the number of sampled noise data over the jamming threshold for detecting the jamming. For a jamming suppression technique, we design the time domain jamming suppression, transmit/receive power control and frequency hopping methods. To assess more realistic operation, the radar altimeter was performed a field test. Through the field test, we verified the algorithms successfully.

• 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.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.6
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• pp.833-840
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• 2013

A radar altimeter which measures the distance using radio wave developed by domestic technology has been applied to various missiles. It is used also for calculating the error of integrated navigation technique. There are a couple of methods to reduce the error but in this paper, we proposed to utilize existing C-band radar altimeter main body with frequency conversion. We designed and manufactured the frequency converter and Ku-band antenna to accomplish this goal. From the test results of products' function and performance, we could expect the possibility of applying this method to enhance the missiles' integrated performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.6
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• pp.555-563
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• 2015

This paper presents signal processing algorithms of a frequency-modulated continuous-wave(FMCW) radar altimeter and provides a practical assessment technique. The radar altimeter is initially operated in search mode, when the radar altimeter detects a valid altitude, search mode is switched to track mode and a altitude being tracked is displayed. The sweep bandwidth in each mode is a function of altitude to narrow the beat frequency bandwidth. In addition, transmit power and receiver gain in each mode are controlled to compensate for the dynamic range of wide altitude range. To assess more realistic operation, the radar altimeter was tested using the crane setup. The crane test demonstrated that signal processing algorithms described in this paper resulted in a reduced measurement error rate.

• Proceedings of the KSRS Conference
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• 2000.04a
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• pp.55-60
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• 2000

인공위성의 Radar Altimeter 자료를 통해 국지적인 중력이상을 조사하기 위하여 ERS-1 Altimeter를 이용하였다. ERS-1 Radar Altimeter는 조밀하게 인접한 데이터 간격(~8km)을 갖고 있어서 전지구적 규모뿐만 아니라 국지적인 연구에도 적합하다. 연구대상지역은 세 개의 판이 만나서 지진과 화산활동이 활발하게 진행되는 필리핀판 지역(동경1$10^{\circ}$~150$^{\circ}$, 북위 0$^{\circ}$~30$^{\circ}$)을 선정하였다. 이 지역에 대한 해저의 지형과 중력 이상 분석을 통해 판구조 운동의 여러 증거를 파악할 수 있다. ERS-1 Radar Altimeter를 통해 얻어진 지오이드 높이(Geoid geight)는 후리-에어 중력이상(Free-air gravity anomaly)으로 쉽게 전환시킬 수 있다. 본 연구에서는 Fast Fourier Transform(FFT)을 이용하여 지오이드기복을 직접 후리-에어 중력이상으로 전환시키는 Direct conversion method를 사용하였다. 후리-에어 중력이상은 지각평형과 직접적으로 연관되어 지각보상의 정도를 파악할 수 있게 하며 일반적으로 해양의 분지는 지각평형상태로 있어서 평균적인 중력이상은 0mgal 근처로 나타난다. 그러나 본 연구에서 살펴본 국지적인 후리-에어 중력이상은 판구조론과 관련한 해구난 호상열도에서는 해양분지에서의 평균적인 값과 다른 중력이상의 양상을 나타내었다.