MTI Improvement Factors For Weighted DFTs

The use of the discrete Fourier transform (DFT) to enhance the detection of moving targets in ground clutter is examined. The improvement factor, defined as the signal-to-clutter ratio at the DFT processor output compared with that of the input, is given as a function of normalized clutter spectral width for various weighting functions on the DFT input. The effect of quantization of the weights on the improvement factor is also examined. Copyright © 1980 by The Institute of Electrical and Electronics Engineers, Inc

Equalization Of QPSK Data Transmission In Specular Multipath

This paper gives performance results for transversal-filter equalization of Quadri phase phase-shift-keyed (QPSK) signals with two-component multipath and demodulator phase error. An analytical expression for optimum, minimum mean-square-error tap weights in terms of the multipath and signal parameters is given. Probability of error results for no equalization and equalization with adaptive decision-feedback tap-weight adjustment are compared. The results show that significant improvement can be obtained with relatively simple equalizer structures. Copyright © 1974 by The Institute of Electrical and Electronics Engineers, Inc

Hybrid Carrier And Modulation Tracking Loop Performance In RFI

The operation of a hybrid Tracking (HT) phase-locked loop (PLL) in radio-frequency interference (RFI) is considered. Results from a perturbation analysis for the loop phase error in continuous-wave (CW) RFI are found to compare favorably with results obtained by digital computer simulation. These results, together with simulation results for wide-band (in comparison to the loop bandwidth) RFI, indicate that loop structures which track both on the signal carrier and modulation components are advantageous in RFI plus Gaussian noise backgrounds. Copyright © 1974 by The Institute of Electrical and Electronics Engineers, Inc

Improving QPSK Transmission In Band-Limited Channels With Interchannel Interference Through Equalization

This paper describes the use of equalization in conjunction with channel filtering to improve QPSK transmission subject to both InterSymbol interference (ISI) and interchange interference (ICI). Performance bounds are computed using the nonclassical Gauss-quadrature rule (GQR) method. The signal-to-noise ratio (SNR) gain due to linear equalization over Non equalization is thereby obtained and presented. The performance of a linear equalizer thus obtained is compared with the Viterbi algorithm sequence estimator (VASE). In the absence of bounds for the VASE receiver under the channel conditions considered, simulation results are used to make the comparison. With a possible difference in the accuracies of the performance thus obtained it is shown that the VASE provides improved performance over the linear equalizer under the channel conditions considered. Copyright © 1977 by The Institute of Electrical and Electronics Engineers, Inc

Conversion And Matched Filter Approximations For Serial Minimum-Shift Keyed Modulation

Serial minimum-shift keyed (MSK) modulation, a technique for generating and detecting MSK using series filtering, is ideally suited for high data rate applications provided the required conversion and matched filters can be closely approximated. Low-pass implementations of these filters as parallel inphase-and quadrature-mixer structures are characterized in this paper in terms of signal-to-noise ratio (SNR) degradation from ideal and envelope deviation. Several hardware implementation techniques utilizing microwave devices or lumped elements are presented. Optimization of parameter values results in realizations whose SNR degradation is less than 0.5 dB at error probabilities of 10-6. © 1982 IEE

Performance Degradation Due To Specular Multipath Intersymbol Interference

Plots of performance degradation are used to compare the effects of fading and intersymbol interference in a two-component specular multipath digital communications channel. Similar plots are then used to compare two practical receivers designed to combat the interference. Degradation plots are shown to allow easy identification of each receiver\u27s range of usefulness, as well as identification of variance bounds demanded of channel parameter estimates which the receivers require. Copyright © 1973 by The Institute of Electrical and Electronics Engineers, Inc

A Microcomputer-Based Data Acquisition System with Hardware Capabilities to Calculate a Fast Fourier Transform

The Fast Fourier Transform (FFT) Has in Recent Years Become an Important Tool to the Engineer. There Are a Number of Algorithms Which Calculate the FFT. One Such Algorithm is the Cooley-Tukey FFT Algorithm (Radix-2) Which Lends itself Rather Easily to a Combination Software and Hardware Implementation. with a Microcomputer as the Controller of a Data Acquisition Module and Hardware Which Computes the Butterfly Associated with the FFT Algorithm, the FFT Can Be Calculated Efficiently. © 1979 IEE

Toward More Meaningful Laboratory Experiences in Digital Signal Processing and Digital Control

Digital Signal Processing and Digital Control Are of Utmost Importance for Electrical Engineering Students, for They Are Present in Many Aspects of Today\u27s Technical World. Complex Topics Like These Should Not Be Introduced into a Curriculum as a Crash Program but Taken as Steps in an Evolutionary Process. a Successful Example of This Evolutionary Process is Well Underway at the University of Missouri-Rolla. Copyright © 1979 by the Institute of Electrical and Electronics Engineers, Inc