scholarly journals Modified Radar Signal Model using NLFM

2019 ◽  
Vol 8 (2S3) ◽  
pp. 513-516
Keyword(s):  
Interference Mitigation ◽  
Matched Filter ◽  
Signal To Noise Ratio ◽  
Nonlinear Function ◽  
Side Lobe ◽  
Radar Signal ◽  
Target Range ◽  
Nonlinear Frequency ◽  
Good Resolution ◽  
Signal Model

Intended to the setback of high side lobes of the linear frequency modulation (LFM) signal, we put forward a new signal model using nonlinear frequency (NLFM) signal to overcome the issue. NLFM is a promising way for achieving lower signal to noise ratio, good resolution and better interference mitigation. The novel signal model is designed to enhance the target range estimation and to reduce the side lobe levels. In this paper, a new signal model is designed based on the principle of fusion of two stages. First stage is exponential based nonlinear function and the second stage is a linear function. The simulations were performed for the designed signal model and are compared with the NLFM signal designed using two stage LFM functions. Simulation results show that the designed signal has significant reduction in side lobe levels of the matched filter response

scholarly journals Evaluation of a class of NLFM radar signals

2019 ◽  
Vol 2019 (1) ◽  
Author(s):  
Sebastian Alphonse ◽  
Geoffrey A. Williamson
Keyword(s):  
Search Space ◽  
Frequency Function ◽  
Radar Signal ◽  
Optimized Design ◽  
Nonlinear Frequency ◽  
Signal Design ◽  
Signal Model ◽  
Radar Systems ◽  
Comprehensive Comparison

AbstractSignal design is an important component for good performance of radar systems. Here, the problem of determining a good radar signal with the objective of minimizing autocorrelation sidelobes is addressed, and the first comprehensive comparison of a range of signals proposed in the literature is conducted. The search is restricted to a set of nonlinear, frequency-modulated signals whose frequency function is monotonically nondecreasing and antisymmetric about the temporal midpoint. This set includes many signals designed for smaller sidelobes including our proposed odd polynomial frequency signal (OPFS) model and antisymmetric time exponentiated frequency modulated (ATEFM) signal model. The signal design is optimized based on autocorrelation sidelobe levels with constraints on the autocorrelation mainlobe width and leakage of energy outside the allowed bandwidth, and we compare our optimized design with the best signal found from parameterized signal model classes in the literature. The quality of the overall best such signal is assessed through comparison to performance of a large number of randomly generated signals from within the search space. From this analysis, it is found that the OPFS model proposed in this paper outperforms all other contenders for most combinations of the objective functions and is expected to be better than nearly all signals within the entire search set.

scholarly journals Selection of window for inter-pulse analysis of simple pulsed radar signal using the short time Fourier transform

2015 ◽  
Vol 4 (4) ◽  
pp. 531 ◽  
Author(s):  
Ashraf Adamu Ahmad ◽  
Abdullahi Daniyan ◽  
David Ocholi Gabriel
Keyword(s):  
Fourier Transform ◽  
Signal To Noise Ratio ◽  
Additive White Gaussian Noise ◽  
Side Lobe ◽  
Radar Signal ◽  
Short Time Fourier Transform ◽  
Time Frequency ◽  
Window Functions ◽  
Pulse Analysis ◽  
Short Time

The electronic intelligence (ELINT) system is used by the military to detect, extract information and classify incoming radar signals. This work utilizes short time Fourier transform (STFT) - time frequency distribution (TFD) for inter-pulse analysis of the radar signal in order to estimate basic radar signal time parameters (pulse width and pulse repetition period). Four well-known windows functions of different and unique characteristics were used for the localization of STFT to determine their various effects on the analysis. The window functions are Hamming, Hanning, Bartlett and Blackman window functions. Monte Carlo simulation is carried out to determine the performance of the signal analysis in presence of additive white Gaussian noise (AWGN). Results show that the lower the transition of main lobe width and higher the peak side lobe, the better the performance of the window function irrespective of time parameter being estimated. This is because 100 percent probability of correct estimation is achieved at signal to noise ratio of about -2dB for Bartlett, 4dB for both Hamming and Hanning, and 9dB for Blackman.

scholarly journals Frequency Diversity Gain of a Wideband Radar Signal

2021 ◽  
Vol 13 (23) ◽  
pp. 4885
Author(s):  
Mengmeng Shen ◽  
Feng He ◽  
Zhen Dong ◽  
Xing Chen ◽  
Lei Yu ◽  
...  
Keyword(s):  
Detection Probability ◽  
Signal To Noise Ratio ◽  
Optimal Number ◽  
Diversity Gain ◽  
Practical Significance ◽  
Radar Signal ◽  
Target Range ◽  
Frequency Diversity ◽  
Target Model ◽  
Wideband Radar

Wideband radar has high-range directional resolution, which can effectively reduce the fluctuation of echo and improve the detection probability of a target under the same detection probability requirement. In this paper, a unified wideband radar χ2 distribution target model with more practical significance is innovatively established, on which the probability density function and detection probability function of Swerling 0, Swerling II and Swerling IV targets are analyzed, respectively. A generalized “frequency diversity gain” of wideband radar is proposed and defined based on the contradiction between suppression of fluctuation and accumulation loss, which represents the ratio of Signal-to-Noise Ratio (SNR) gain between broadband signal and reference bandwidth signal under the same condition (when the reference bandwidth is used, the radar target has only one range unit), and the mathematical relation equation of the target detection performance and signal bandwidth (equivalent to the number of distinguishable range elements of the target) is given. A Monte Carlo simulation experiment is designed. Based on the target model established in this paper, the optimal number of target range units corresponding to different detection probability requirements is obtained, which verifies the correctness of the concept proposed in this paper.

scholarly journals Enhancement of Matched Filter Response for Chirp Radar Signals using Signal Recovery Technique

2019 ◽  
Vol 9 (2) ◽  
pp. 561-565
Keyword(s):  
Matched Filter ◽  
Signal To Noise Ratio ◽  
Side Lobe ◽  
Detection Performance ◽  
Signal Recovery ◽  
Reconstruction Process ◽  
New Approach ◽  
Recovery Technique ◽  
Radar Signals ◽  
Filter Response

The matched filter is one among many effective techniques used to maximize the signal –to- noise ratio (SNR) of chirp radar signals. Besides this enhancement in SNR, it has a drawback due to sidelobe levels which degrade the filter response. There are many additional techniques which reduce these levels such as window techniques and inverse filter. In this paper, a new approach is utilized to completely cancel the level of matched filter side lobes based on the signal recovery of the compressive sensing (CS) theory. The reconstruction process of CS is based on the CAMP algorithm which applied to the response of the matched filter. The recovered chirp radar signals are achieved with completely side lobes cancellation compared to the traditional side lobe reduction technique based on the widow method. The comparison between the proposed and traditional methods is achieved according to the detection performance using Receiver Operating Characteristic (ROC) curve. Besides the detection performance, a resolution in the range is another comparison aspect between these algorithms.

scholarly journals Piggyback search for fast radio bursts using Nanshan 26 m and Kunming 40 m radio telescopes – I. Observing and data analysis systems, discovery of a mysterious peryton

2019 ◽  
Vol 488 (3) ◽  
pp. 3957-3971 ◽  
Author(s):  
Y P Men ◽  
R Luo ◽  
M Z Chen ◽  
L F Hao ◽  
K J Lee ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Interference Mitigation ◽  
Matched Filter ◽  
Signal To Noise Ratio ◽  
Dispersion Measure ◽  
Radio Bursts ◽  
Similar Frequency ◽  
New Radio ◽  
Radio Signals ◽  
Measure Index

ABSTRACT We present our piggyback search for fast radio bursts using the Nanshan 26 m Radio Telescope and the Kunming 40 m Radio Telescope. The observations are performed in the L band from 1380 to 1700 MHz at Nanshan and the Sband from 2170 to 2310 MHz at Kunming. We built the roach2-based FFT spectrometer and developed the real-time transient search software. We introduce a new radio interference mitigation technique named zero-DM matched filter and give the formula of the signal-to-noise ratio loss in the transient search. Though we have no positive detection of bursts in about 1600 and 2400 h data at Nanshan and Kunming, respectively, an intriguing peryton was detected at Nanshan, from which hundreds of bursts were recorded. Perytons are terrestrial radio signals that mimic celestial fast radio bursts. They were first reported at Parkes and identified as microwave oven interferences later. The bursts detected at Nanshan show similar frequency swept emission and have double-peaked profiles. They appeared in different sky regions in about tens of minutes observations and the dispersion measure index is not exactly 2, which indicates the terrestrial origin. The peryton differs drastically from the known perytons detected at Parkes, because it appeared in a precise period of p = 1.712 87 ± 0.000 04 s. Its origin remains unknown.

scholarly journals Comparison of the performance of different radar pulse compression techniques in an incoherent scatter radar measurement

2009 ◽  
Vol 27 (2) ◽  
pp. 797-806 ◽  
Author(s):  
B. Damtie ◽  
M. S. Lehtinen
Keyword(s):  
Adaptive Filtering ◽  
Pulse Compression ◽  
Matched Filter ◽  
Signal To Noise Ratio ◽  
Minimum Mean Square Error ◽  
Radar Signal ◽  
Incoherent Scatter Radar ◽  
Low Snr ◽  
Incoherent Scatter ◽  
Scatter Radar

Abstract. Improving an estimate of an incoherent scatter radar signal is vital to provide reliable and unbiased information about the Earth's ionosphere. Thus optimizing the measurement spatial and temporal resolutions has attracted considerable attention. The optimization usually relies on employing different kinds of pulse compression filters in the analysis and a matched filter is perhaps the most widely used one. A mismatched filter has also been used in order to suppress the undesirable sidelobes that appear in the case of matched filtering. Moreover, recently an adaptive pulse compression method, which can be derived based on the minimum mean-square error estimate, has been proposed. In this paper we have investigated the performance of matched, mismatched and adaptive pulse compression methods in terms of the output signal-to-noise ratio (SNR) and the variance and bias of the estimator. This is done by using different types of optimal radar waveforms. It is shown that for the case of low SNR the signal degradation associated to an adaptive filtering is less than that of the mismatched filtering. The SNR loss of both matched and adaptive pulse compression techniques was found to be nearly the same for most of the investigated codes for the case of high SNR. We have shown that the adaptive filtering technique is a compromise between matched and mismatched filtering method when one evaluates its performance in terms of the variance and the bias of the estimator. All the three analysis methods were found to have the same performance when a sidelobe-free matched filter code is employed.

Simulation Research on how to Improve the Range Resolution of Pulse Compression Radar Based on Phase Coding

2011 ◽  
Vol 143-144 ◽  
pp. 634-638 ◽  
Author(s):  
Yu Tang
Keyword(s):  
Compression Ratio ◽  
Pulse Compression ◽  
Matched Filter ◽  
Side Lobe ◽  
Radar System ◽  
Radar Signal ◽  
Pulse Modulation ◽  
Range Resolution ◽  
Set Up ◽  
Barker Codes

Phase coded radar signal is one of the pulse-pulse modulation signal in the radar system. Based on the characteristics of matched filtering, we theoretically analyze the basic principle of the phase coded compression radar system. In the Matlab platform, we set up a simulation model which is used for matching filter, when the radar transmitting signal is Barke code signal. The simulation results show that Echo signal can obtain certain pulse compression ratio. By the matched filter, the main lobe amplitude of 13 bits Barker code signal is 22 times the rate of side-lobe. 13 bits Barker codes by the matched filter have the maximum pulse compression ratio.

scholarly journals Simulation and Performance Analysis of Chaotic Sequences using Enhanced Cuckoo Search Optimization Method

2019 ◽  
Vol 8 (4) ◽  
pp. 10225-10231
Keyword(s):  
Adaptive Filters ◽  
Pulse Compression ◽  
Matched Filter ◽  
Search Algorithm ◽  
Signal To Noise Ratio ◽  
Cuckoo Search ◽  
Optimization Method ◽  
Chaotic Sequence ◽  
Radar Signal ◽  
Linear Filter

The mostdesirable property required for pulse compression is that the output should have low peak sidelobes that prevent weaker targets from being masked off in the nearby strong targets. Pulse compression can be obtained with matched filter. Matched filter is an optimal linear filter used in radar signal processing and various communication fields to increase the signal to noise ratio. The output of matched filter consists of unavoidable sidelobes which causes false alarm for multiple target detection in many radar system design.For this purpose, mismatched filter is used after matched filter. Inthis paper a new method of design of mismatched filter is discussed which reduces these sidelobes in the compressed waveform. Here new version of cuckoo search algorithm is used along with differential evolution techniquefor complete design of proposed filter to compare the performance of chaotic sequence. The performance of pulse compression is measured in terms of peak sidelobe ratio. The simulation results showthatdevelopmentin the performance of chaotic sequence is obtained at the output of cascaded filter. And further improved performance is achieved with adaptive filters

scholarly journals Estimating the Instantaneous Frequency of Linear and Nonlinear Frequency Modulated Radar Signals—A Comparative Study

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2840
Author(s):  
Hubert Milczarek ◽  
Czesław Leśnik ◽  
Igor Djurović ◽  
Adam Kawalec
Keyword(s):  
Instantaneous Frequency ◽  
Early Warning Systems ◽  
Vital Role ◽  
Estimation Methods ◽  
Radar Signal ◽  
Nonlinear Frequency ◽  
Modulation Recognition ◽  
Electronic Warfare ◽  
Time Frequency ◽  
Radar Signals

Automatic modulation recognition plays a vital role in electronic warfare. Modern electronic intelligence and electronic support measures systems are able to automatically distinguish the modulation type of an intercepted radar signal by means of real-time intra-pulse analysis. This extra information can facilitate deinterleaving process as well as be utilized in early warning systems or give better insight into the performance of hostile radars. Existing modulation recognition algorithms usually extract signal features from one of the rudimentary waveform characteristics, namely instantaneous frequency (IF). Currently, there are a small number of studies concerning IF estimation methods, specifically for radar signals, whereas estimator accuracy may adversely affect the performance of the whole classification process. In this paper, five popular methods of evaluating the IF–law of frequency modulated radar signals are compared. The considered algorithms incorporate the two most prevalent estimation techniques, i.e., phase finite differences and time-frequency representations. The novel approach based on the generalized quasi-maximum likelihood (QML) method is also proposed. The results of simulation experiments show that the proposed QML estimator is significantly more accurate than the other considered techniques. Furthermore, for the first time in the publicly available literature, multipath influence on IF estimates has been investigated.

Sign in / Sign up

Export Citation Format

Share Document