Implementation Of Matched Filter Research Articles

IMPLEMENTATION OF A MATCHED FILTER FOR LFM SIGNALS USING A SYSTEM-ON-CHIP BASED SDR TRANSCEIVER

Background. Creation of communication channels with effective protection against intentional interference is the most urgent task for communication channels of unmanned aerial vehicles (UAVs). An effective solution is the use of signals with spectrum expansion, which allows reducing the impact of intentional interference on control and telemetry channels, thereby increasing the survivability of UAVs. The most optimal is the use of LCM modulation, which became possible with the development of SDR and SoC technologies. The main problem of using LFM modulation is the complexity of implementing matched filters. This requires research to create optimal digital implementations of matched filters. Objective. The purpose of the paper is to determine the parameters of the LFM signal for the implementation of the communication system using CSS modulation on the SDR transceiver. Optimal implementation of discrete matched filter (correlator) for CSS BOK modulation on FPGA (SoC). Methods. Analysis of the possibilities of implementing CSS BOK modulation for building a communication system based on SDR transceivers. Analysis of optimal options for building a discrete matched filter (correlator) for CSS BOK modulation on FPGA (SoC) and its implementation. Testing on a laboratory bench. Results The possibility of creating a communication system based on an SDR transceiver using CSS BOK modulation has been confirmed. The optimal parameters of the LFM signal, which can be implemented, have been studied. An implementation of a discrete matched filter (correlator) for CSS BOK modulation on FPGA has been developed. Testing carried out on a laboratory bench using SDR transceivers AD9361 (AD9364) showed the correctness and effectiveness of the decisions made. Conclusions The parameters of the LFM signal for the implementation in the communication system using CSS modulation on the SDR transceiver have been studied and determined. It was determined that when using the AD9361 (AD9364) transceiver, it is possible to implement an LFM signal with a band of up to 25 MHz, while the optimal symbol duration will be 16.6667 µsec at 1024 counts and a sampling frequency of 61.44 MHz. It was determined that the best CSS modulation method for creating a communication system is the binary orthogonal manipulation (BOK) method, which allows you to effectively use the advantages of SDR technologies, in particular, the ease of working with quadrature channels and, as a consequence, the ease of implementing phase synchronization. It has been determined that the best method of implementing a matched filter (correlator) on the basis of FPGA (SoC) is the application of fast convolution based on the fast Fourier transform. The developed implementation of a discrete matched filter (correlator) for CSS BOK modulation on FPGA showed the possibility of implementing a communication system with CSS BOK modulation on an SDR transceiver in full accordance with the research results. Experimental studies were carried out on a laboratory bench using SDR transceivers AD9361 (AD9364), which fully confirmed the results of simulation modelling.

Matched Filter Implementation, Complexity, and Gain in Fractional Fourier Domain

The radar matched filter is implemented in fractional Fourier domain (FrFD) and the required processing steps to perform the radar matched filter in FrFD are demonstrated. The complexity of the FrFD matched filter over the normal frequency transform matched filter is also investigated. The performance enhancements for using the matched filter in the FrFD are presented and the enhancement in the signal to noise ratio (SNR) output at different target SNRs are also described.

Linear Canonical Matched Filter: Theory, Design, and Applications

The linear canonical transform (LCT) is a multiparameter unitary transform that generalizes a large number of classical transforms with application to signal processing and optics. Many of its fundamental properties are already known; however, little attention has been paid to the design and implementation of matched filters in the LCT domain. The objective of this paper is to design this type of filters that maximize the output signal-to-noise ratio, dubbed the linear canonical matched filter (LCMF). We first derive some facts of the LCT spectral analysis for random signals. Then, by applying the derived results, the LCMF design theory associated with the LCT is developed. Moreover, the implementation and basic properties of the LCMF are presented. The introduction of the LCMF invites a new interpretation of the ambiguity function and the correlation function of the LCT. Finally, we provide several applications for the theoretical derivations.

Design and Implementation of Multisteerable Matched Filters

Image analysis problems such as feature tracking, edge detection, image enhancement, or texture analysis require thedetection of multi-oriented patterns which can appear at arbitrary orientations. Direct rotated matched filtering for feature detection is computationally expensive, but can be sped up with steerable filters. So far, steerable filter approaches were limited to only one direction. Many important low-level image features are, however, characterized by more than a single orientation. We therefore present here a framework for efficiently detecting specific multi-oriented patterns with arbitrary orientations in grayscale images. The core idea is to construct multisteerable filters by appropriate combinations of single-steerable filters. We exploit that steerable filters are closed under addition and multiplication. This allows to derive a design guide for multisteerable filters by means of multivariate polynomials. Furthermore, we describe an efficient implementation scheme and discuss the use of weighting functions to reduce angular oscillations. Applications in camera calibration, junction analysis of images from plant roots, and the discrimination of L, T, and X-junctions demonstrate the potential of this approach.

Ground-based photometric detection of extrasolar planets

The discovery of terrestrial-sized extrasolar planets around main-sequences stars is currently possible from the ground for several sub-solar, small-radii eclipsing binary systems. Terrestrial planets in these systems should form in the binary orbital plane, and are likely to have periods significantly smaller than those of the terrestrial planets in the Solar System, and hence, should be more easily detectable. Our observations of the CM Draconis system indicate that such detections are indeed possible, especially when the photometric data (differential light curve) can be correlated with possible planetary orbital models of the quasi-periodic signal expected (i.e. a matched-filter implementation). The importance of the discovery of the first habitable planets, and follow-up observations for the detection of exobiology are outlined. In addition, non-transiting jovian-mass planets in such systems can also be detected by precisely timing the binary eclipse minima. Our preliminary observations of ten such systems have demonstrated the feasibility of this detection method. Over two hundred such systems could be surveyed for jovian-mass planets, providing a statistically meaningful sample for understanding the formation of giant planets around close double stars, thus complimenting our main objective: the detection of habitable-sized planets.

A comparison of analog and digital circuit implementations of low power matched filters for use in portable wireless communication terminals

In this paper, analog and digital circuit realizations of a parallel programmable matched filter are examined. Through wide variations of the design space parameters, the general trend that is observed is that short, fast circuits tend to favor an analog implementation, while longer, slower circuits make a digital implementation more appropriate. A methodology is provided for choosing the preferable circuit-implementing technology when power consumption-as a function of data precision, filter length, operating frequency, technology scaling, and the maturity of the fabrication process-is used as the primary metric of comparison. It is shown that neither the analog nor the digital matched filter implementation is universally more power efficient than the other. Rather, a surface is mapped in the multidimensional design space where, on one side of this surface, a digital solution is preferable, while on the other side of the surface, an analog circuit is appropriate. Equations are given which delineate the position of this transitional surface in terms of the design space parameters, and example calculations and plots depicting the regions of dominance for the digital and analog matched filters for specific process and system parameters are presented.

Filtering of moving targets using SBIR sequential frames

In this paper three-dimensional (3-D) finite-impulse response (FIR) filters are proposed for moving target detection and tracking from multiframe space-based infrared (SBIR) data. An optimal, in the l/sub p/ sense, 3-D FIR filter design technique is proposed which is suitable for the above application. This technique is the first 3-D FIR design of its kind presented in the open literature. Directional, matched, and adaptive 3-D filtering techniques are proposed. Prior to the filtering, clutter mean estimation and mean subtraction are required. Real time implementation of directional and/or matched filters for processing maneuvering targets is discussed and filter design methods are proposed. Finally, performance comparisons of the proposed and other available 3-D FIR and infinite-impulse response (IIR) filters, on real SBIR data, are presented in which the advantages of the proposed 3-D filters are shown. >

Scale-invariant binary phase-only matched filter using a ferroelectric-liquid-crystal spatial light modulator

We describe the implementation of a scale-invariant binary phase-only matched filter using a 128 × 128 ferroelectric spatial light modulator. A 5-dB discrimination was obtained between a 10-image training set of highly correlated characters (E's and F's) over a scale range of 1.0 to 1.5.

Efficient matched filter for the generalized chirp-like polyphase sequences

The efficient implementation of the matched filter for the generalized chirp-like (GCL) polyphase sequences is presented. These sequences can be classified as the modulatable orthogonal sequences, because they can be modulated by a string of arbitrary complex numbers of unit magnitude, retaining the ideal periodic autocorrelation function and optimum crosscorrelation function. For the applications in spread-spectrum system, where the sequence length can be significantly large, it is highly important to minimize the complexity of the corresponding matched filter. The new efficient implementation of the matched filter is based on the algebraic decomposition of GCL sequences. Some interesting special cases of the efficient pulse compressors, proposed previously for P3 and P4 codes are obtained. The subclass of GCL sequences which permits even more efficient matched filter implementation for any length N=sm/sup 2/ is derived. It is shown that such a subclass of the GCL sequences comprises the so-called generalized Frank sequences, which can be obtained as a special case of the GCL sequences of length N=m/sup 2/. >

Comparison between linear FM and phase-coded CW radars

The classical linear FM CW radar signal is compared with P3 and P4 phase-coded CW signals. The comparison covers the theoretical delay-Doppler response, the spectrum and the performances in digital receiver processors. The receivers produce a matrix of delay and Doppler cells. Three receiver approaches are considered: (a) Doppler compensation followed by a multicorrelation processor. This is a general and efficient implementation of many matched filters, which applies to any phase-coded signal. (b) A modification of (a), applicable to P3, P4 signals, in which the multicorrelators are efficiently replaced by FFTs, without altering the performances. (c) A single correlator followed by two levels of spectral analysis, for range and for Doppler. In the two matched filter implementations, (a) and (b), the P signals exhibit lower range sidelobes, due to their inherent property of perfect periodic autocorrelation. The LFM signal requires additional weighting (hence additional SNR loss) and even then does not approach the low range sidelobes of P signals. In the single correlator receiver, the two signals exhibit almost identical performances, which are similar to the performances of LFM in the matched receiver.

Experimental Results for Four-Phase Digital Matched Filtering of Spread-Spectrum Waveforms

In this paper, the implementation and experimental testing of a noncoherent four-phase digital matched filter (DMF) is presented. The DMF represents the experimental realization of A. Baier's theory of complex valued envelope matched filtering [1].

Implementation of digital matched filters in data receivers

It is shown that analogue-filter and analogue-detector circuits in data receivers can be replaced by simple digital networks designed from truth-table specifications. A method of compiling truth tables from given received-signal probabilities is presented. An example illustrates an application to the reception of binary raised cosine signals in the presence of Gaussian noise.