摘要:

Satellite communications have advanced from the realm of science fiction to the commonplace in a period of less than 40 years. The paper outlines the birth and development of this new industry which was pioneered by the United States and the Soviet Union but has since become increasingly international, with growing capabilities in Western Europe, Japan, China and India. The technological developments which have accompanied the growth of satellite communications have been both diverse and complex. To illustrate the rapid technological advance in communications, three phases have been identified which are linked by major changes in the state-of-the-art. The concept of the sky-hook, the end of the fish-warmers and the era of the hub-cap provide convenient milestones against which this dramatic advance can be calibrated.

DOI:10.1049/ip-f-1.1985.0001

出版商:IEE    

年代:1985

数据来源: IET

摘要:

Through proper use of a Hamming window, approximate relationships are established among the coefficients of half-band FIR filters, which may be realised conveniently as delta modulation (DM) filters by simple and economical hardware. The procedure is demonstrated by means of two design examples. Experimental results confirm the theoretical predictions.

DOI:10.1049/ip-f-1.1985.0002

出版商:IEE    

年代:1985

数据来源: IET

摘要:

A very rapidly convergent solution (in the form of a likelihood ratio test) for the problem of detecting a discrete-time stochastic process in additive white Gaussian noise has been derived. This likelihood ratio test is applied to the problem of moving-target detection as encountered in an airport-surveillance radar system. Using real radar data, the receiver operating characteristics are obtained for two different implementations of this adaptive detection algorithm, and for the three generations of the classical moving-target-detection algorithm presently in use in modern radar systems. The best of the two implementations of the adaptive detection algorithm employs Kalman prediction tapped delay-line filters and attains a minimum of 3 dB average performance improvement relative to the classical moving-targer-detection algorithms.

DOI:10.1049/ip-f-1.1985.0003

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The suboptimum detection procedure based on the weighting of partial decisions (WPD) was introduced as an improvement of one-bit-quantisation digital matched filtering, also known as binary matched filtering (BMF). The WPD is characterised by minimal additional hardware and software requirements but considerably better performance in comparison with BMF. A primary application of the WPD is the implementation of cost-effective medium-speed voice-band data medem receivers, but it can also be used in a number of other parametric and nonparametric detection problems. Formerly, the WPD was analysed only for binary transmission with an antipodal set of signalling waveforms. In this paper, the concept of the WPD is generalise and analysed theorectically forM-ary transmission with an arbitrary set of equal-energy signalling waveforms. Here, it is treated as the generalise procedure with BMF is its special case. The results of the performance analysis are provided, as well.

DOI:10.1049/ip-f-1.1985.0004

出版商:IEE    

年代:1985

数据来源: IET

摘要:

A radar system is considered in which the detection and tracking functions are completely integrated. The system parameters are then chosen to minimise the mean-square tracking error of the integrated system. An analytical result is applied which allows the impact of detection errors on tracking accuracy. This was the first known result of this nature, as usually detection and tracking are viewed as independent functions, with the detection process regarded as perfect in assessing tracking accuracy. The result is partly empirical, and herein we test it in a digital-computer simulation. The performance objective of the integrated detection and tracking system is to minimise the mean-square tracking error, subject to the constraint that the probability of a track not being lost exceeds a prescribed value. We also consider multitarget environments and show how to allocate radar resources such that the average tracking error is minimal. Using a digital-computer simulation, our results show that considerable performance improvement results when radar resources are optimally allocated relative to a scheme where every target shares the radar resources on an equal basis. An electronic scanning capability for the radar is assumed throughout our work. A shortcoming of the research is the assumption that radar returns, when detected, are always associated with the true track. However, false alarms as a degradation in the track-measurement process are included in our work.

DOI:10.1049/ip-f-1.1985.0005

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The applicability of two relatively new linear FM matched filtering algorithms to the processing of synthetic-aperture radar (SAR) data is examined and compared to the fast-convolution algorithm. The algorithms, called basic spectral analysis and the step transform, use the properties of the linear FM signal to achieve some significant performance improvements. The algorithms are evaluated on the basis of their ability to deal with problems peculiar to the SAR application, such as multilooking, range-cell migration, and variations in the FM rate of the input signal. Computation rates are also derived as a function of resolution and target return signal aperture. It is shown that no one algorithm is optimal for all cases. The basic-spectral-analysis algorithm has the lowest computation rate at low resolutions, but has an output data rate which varies with the FM rate and cannot correct for nonlinear data shifts called range curvature. The step transform has the most efficient computation rate at high resolutions. It also has a constant output data rate and can correct for range curvature. The fast-convolution algorithm has a lower computation rate than the step transform at low resolutions and can meet all of the SAR requirements mentioned. All of the algorithms are able to perform multilook processing.

DOI:10.1049/ip-f-1.1985.0006

出版商:IEE    

年代:1985

数据来源: IET

摘要:

A latest-generation or ‘adaptive’ moving target detector (A-MTD) digital processor is described. The A-MTD is based on three banks of filters, to cope with different levels of ground clutter.The paper includes: (i) the technique for the filter design, (ii) the trade-off for the number of bits to represent the filter coefficients (iii) some of the obtained filtering performances (iv) the analysis of the amplitude/phase distortion effects.

DOI:10.1049/ip-f-1.1985.0007

出版商:IEE    

年代:1985

数据来源: IET