• Journal of the Korean Institute of Telematics and Electronics
• /
• v.26 no.6
• /
• pp.140-146
• /
• 1989

In many situations, radar targets are embedded in a clutter environment and clutter rejection is required. The clutter is unwanted radar echoes and may arise owing to reflections from ground and weather disturbances and statistical properties of the clutter vary with range and azimuth as well as time. That is, adaptive signal processing is required. In this paper, a clutter suppression algorithm based on the clutter whitening filter (WF) and doppler filter bank(DFB) is described which provides improved performance compared with conventional nonadaptive clutter suppression algorithm that is the cascaded moving target indicator (MTI) and (DFB). The clutter whitening filter algorithm is based on the Burg's maximum entropy method.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.22 no.10
• /
• pp.1386-1391
• /
• 2018

The radar in the moving platform is interfered by the mainlobe clutter as well as the altitude clutter that is received from sidelobe. The altitude clutter is relatively short range compared to mainlobe clutter and therefore enters the radar with a strong signal. As these clutters are major reason making the probability of false alarm high, it is required to suppress both altitude clutter and mainlobe clutter. In this paper, It is proposed the clutter suppression method consisted of two pulse canceller to suppress the clutters being two frequency area in moving platform. It is analyzed the correlation of output signals according to the use of pulse canceller and provided the structure of staggered pulse canceller considered the correlation. Finally, it shows that altitude clutter and mainlobe clutter are suppressed by proposed staggered pulse canceller using the simulation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.28 no.10
• /
• pp.825-831
• /
• 2017

Radar clutter in real environment is in general heterogeneous and especially nonstationary if radar geometry is of non-sidelooking monostatic structure or bistatic structure. These clutter properties lead to the insufficient number of secondary data of IID(Independent identically distributed) property, conclusively deteriorate clutter suppression performance. In this paper, we propose a clutter suppression algorithm that estimates the clutter signal belonging to cull under test via calculation using only prior information, rather than using the secondary data. Through analyzing the angle-Doppler spectrum of the clutter signal, we show the estimation of the clutter signal using prior information only is possible and present the derivation of a clutter suppression algorithm through eigen-value analysis. Finally, we show the performance of the proposed algorithm by simulation.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.39 no.4
• /
• pp.347-357
• /
• 2003

This paper describes on the suppression of sea clutter on marine radar display using a cell-averaging CFAR(constant false alarm rate) technique, and on the analysis of radar echo signal data in relation to the estimation of ARPA functions and the detection of the shadow effect in clutter returns. The echo signal was measured using a X -band radar, that is located on the Pukyong National University, with a horizontal beamwidth of $$3.9^{\circ}$$, a vertical beamwidth of $20^{\circ}$, pulsewidth of $0.8 {\mu}s$ and a transmitted peak power of 4 ㎾ The suppression performance of sea clutter was investigated for the probability of false alarm between $l0-^0.25;and; 10^-1.0$. Also the performance of cell averaging CFAR was compared with that of ideal fixed threshold. The motion vectors and trajectory of ships was extracted and the shadow effect in clutter returns was analyzed. The results obtained are summarized as follows；1. The ARPA plotting results and motion vectors for acquired targets extracted by analyzing the echo signal data were displayed on the PC based radar system and the continuous trajectory of ships was tracked in real time. 2. To suppress the sea clutter under noisy environment, a cell averaging CFAR processor having total CFAR window of 47 samples(20+20 reference cells, 3+3 guard cells and the cell under test) was designed. On a particular data set acquired at Suyong Man, Busan, Korea, when the probability of false alarm applied to the designed cell averaging CFAR processor was 10$^{-0}$.75/ the suppression performance of radar clutter was significantly improved. The results obtained suggest that the designed cell averaging CFAR processor was very effective in uniform clutter environments. 3. It is concluded that the cell averaging CF AR may be able to give a considerable improvement in suppression performance of uniform sea clutter compared to the ideal fixed threshold. 4. The effective height of target, that was estimated by analyzing the shadow effect in clutter returns for a number of range bins behind the target as seen from the radar antenna, was approximately 1.2 m and the information for this height can be used to extract the shape parameter of tracked target..

• Journal of IKEEE
• /
• v.26 no.4
• /
• pp.524-530
• /
• 2022

When radar return contains strong jammers along with ground clutter echo, a STAP(space-time adaptive processing) algorithms tend to suppress jammer components more severely than it does the clutter. This hinders moving target detection in that the target echo is apt to be buried by clutter echo. This paper presents a two-step STAP algorithm in which the pre-suppression of jammer by the spatial filtering is applied, prior to applying the STAP algorithm. We propose how to find the coefficients of the spatial filter and show that the spatial filtering barely alter the spectra of the target and the clutter echo, having only to suppress the jammers. Finally, we simulate a STAP scenario with strong jammers and show the proposed algorithm can improve STAP performance.

• International Journal of Ocean System Engineering
• /
• v.1 no.1
• /
• pp.52-59
• /
• 2011

A prototype radar display unit was implemented using inexpensive off-the-shelf components, including a nonlinear estimation algorithm for the target tracking in a clutter environment. Two custom designed boards; an analog signal processing board and a DSP board, can be plugged into an expansion slot of a personal computer (PC) to form a maritime radar display unit. Our system provided all the functionality specified in the International Maritime Organization (IMO) resolution A422(XI). The analog signal processing board was used for A/D conversion as well as rain and sea clutter suppression. The main functions of the DSP board were scan conversion and video overlay operations. A host PC was used to run the tracking algorithm of targets in clutter, using the discrete-time Bayes optimal (nonlinear, and non-Gaussian) estimation method, and the graphic user interface (GUI) software for Automatic Radar Plotting Aid (ARPA). The proposed tracking method recursively found the entire probability density function of the target position and velocity by converting into linear convolution operations.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.25 no.3
• /
• pp.456-463
• /
• 2021

In this paper, Ultra Wide-Band(UWB) radar sensor is employed to detect flying drones and avoid collision in dense clutter environments. UWB signal is preferred when high resolution range measurement is required for moving targets. However, the time varying motion of flying drones may increase clutter noises in return signals and deteriorates the target detection performance, which lead to the performance degradation of anti-collision radars. We adopt a dynamic clutter suppression algorithm to estimate the time-varying distances to the moving drones with enhanced accuracy. A modified Constant False Alarm Rate(CFAR) is developed using an adaptive filter algorithm to suppress clutter while the false detection performance is well maintained. For this purpose, a velocity dependent CFAR algorithm is implemented to eliminate the clutter noise against dynamic target motions. Experiments are performed against flying drones having arbitrary trajectories to verify the performance improvement.

• Journal of the Society of Disaster Information
• /
• v.19 no.1
• /
• pp.10-17
• /
• 2023

Purpose: In this paper, a distance estimation technique for indoor location estimation using IR-UWB is proposed and researched. We propose an algorithm that can increase the SNR lowered due to clutter or noise in an indoor environment. Method: In order to clutter suppression and detect weak signals, we analyze the existing studies of background remover, correlation, and singular vector decomposition techniques and propose an algorithm. Result: The proposed algorithm, the average error was 0.57m up to 11.5m, and the error were 0.49m from 6m to 11.5m. the average error rate was reduced by about 1m compared to the previous study. Conclusion: It can be used as a technique for detecting weak signals in clutter and noise environments for distance or location estimation, and can also be used as a human life detection technique to reduce damage to people in a disaster situation by using UWB radar which has highly transparent.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.9 no.3
• /
• pp.95-100
• /
• 2006

The pulse compression technique using Linear FM signal is commonly used for improving the performance of both the detection range and range resolution in radar system. In general, the compressed LFM waveform has relatively large sidelobe level which may prevent a target from being detected when strong jammer or clutter signal is near the target signal. In this paper, we propose a new weighting method which uses the square-root weight to suppress the sidelobe level. Typical applications are missile seekers and tracking radar systems where target tracking range is available prior to the signal processing. By computer simulation, we show that the performance of the proposed method is better than that of the conventional weighting methods in terms of sidelobe suppression.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.29 no.8
• /
• pp.599-607
• /
• 2018

This paper presents a ground-to-air bistatic radar system and its implementation algorithm, which resembles an SAR(synthetic aperture radar) reconstruction algorithm. Via cooperative working between a standoff transmitting radar and an array of ground based receiving radars, it detects and images moving targets under clutter in the air. In the proposed system, the whole receiving antenna aperture is synthesized by physical ground based radars, and thus, unlike conventional SAR, it does not require long illumination time of the target area. The reconstruction algorithm uses planewave approximation based polar format processing, which alleviates the requirement of positioning the receiving radars, which can cause grating lobes if not chosen properly. We derive a reconstruction algorithm including clutter suppression and discuss implementation issues, such as the resolution of a reconstructed image and the method of compensation for the irregularity of the receiving radars' positions. A simulation that validates the proposed algorithm is also shown.