摘要:

A class of finite-state alternate alphabetic line codes, designatedmBL-K, is identified and studied in the context of digital pulse-position modulation (PPM). The influence on code properties of the number of time slots per PPM frame and the number of frames per code word is considered, and a specific 9B2-33 code is identified which is particularly well suited to digital optical-fibre PPM transmission.

DOI:10.1049/ip-f-1.1985.0084

出版商:IEE    

年代:1985

数据来源: IET

摘要:

In the paper, an alternative formulation for an optimum beamformer with a robustness capability against directional errors is presented. With this approach, the width of the main beam can be specified and a compromise can be reached between a reasonable signal acceptance angle and the ability of the beamformer to reject directional interferences. Furthermore, based on a partitioned processor interpretation, the new beam-former gives a clue to a way of reducing the complexity of a full processor.

DOI:10.1049/ip-f-1.1985.0085

出版商:IEE    

年代:1985

数据来源: IET

摘要:

A very efficient technique for the computation of error probability in ASK systems withM= 2m(man integer) symbols or QASK systems withM2symblos in the presence of intersymbols interference was presented by Jenq, Liu and Thomas, and this technique was extended by Jenq to coherent PSK (no phase jitter) withM= 2, 4 and 8 symbols. In the present paper we extend this technique to PSK (phase jitter or misalingnment is possible) with 8 and 16 symbols by deriving lower and upper bounds which are close to each other.

DOI:10.1049/ip-f-1.1985.0086

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The paper presents a number of systolic configurations for computing deconvolutions and discrete Fourier transformations. Two approaches to deconvolution are considered: a time-domain approach, which is based on a systolic inversion of an associated Toeplitz matrix, generated by a wavefront propagation of the known system response, while the other approach, which is in the frequency domain, utilises systolic discrete Fourier transform (DFT) and fast Fourier transform (FFT) processors. The latter employs a systolic elevator concept, which circumvents the traditional need for global communications in the FFT. Aspects of hardware implementation and speed trade-offs are also discussed.

DOI:10.1049/ip-f-1.1985.0087

出版商:IEE    

年代:1985

数据来源: IET

摘要:

A bit level systolic array system is proposed for the Winograd Fourier transform algorithm. The design uses bit-serial arithmetic and, in common with other systolic arrays, features nearest-neighbour interconnections, regularity and high throughput. The short interconnections in this method contrast favourably with the long interconnections between butterflies required in the FFT. The structure is well suited to VLSI implementations. It is demonstrated how long transforms can be implemented with components designed to perform a short length transform. These components build into longer transforms preserving the regularity and structure of the short length transform design.

DOI:10.1049/ip-f-1.1985.0088

出版商:IEE    

年代:1985

数据来源: IET

摘要:

A code-division multiplexing technique using a set of orthogonal functions known as bridge functions as carrier codes has been investigated. These functions are three-valued functions which take the values +1, 0 and −1. The results of a computer simulation on the performance of the system in additive white Gausian noise are presented, and the system is compared with conventional time-division multiplexing.

DOI:10.1049/ip-f-1.1985.0089

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The paper studies three developments of a class of near-maximum-likelihood detection processes derived from a conventional nonlinear (decision feedback) equaliser. The new detectors are suitable for binary signals transmitted over a linear baseband channel introducing severe amplitude distortion. The complexity of the processes is not excessive, and increases approximately linearly with the delay in detection. Thus, a sufficiently large delay in detection can be employed to achieve a near-optimum tolerance to noise when the received signal has been very severely distorted. The paper describes three novel detection processes, and presents the results of computer simulation tests, comparing the tolerances to additive white Gaussian noise of various arrangements of each detector with that of the optimum detector of the given class and that of a conventional nonlinear equaliser. Three different channels are used in the tests and binary signals are transmitted in every case.

DOI:10.1049/ip-f-1.1985.0091

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The maximum entropy method assumes that the spectrum exists up to the Nyquist frequency. For array processing of low-frequency signals, the spectrum often only exists over part of the wavenumber interval. This paper generalises the maximum entropy methods to correctly model this situation. Simulations are included which show the performance of the technique.

DOI:10.1049/ip-f-1.1985.0092

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The paper presents a maximum entropy technique for recovering a band-limited spectrum from noisy measurements. It is demonstrated that the new technique is capable of forming a good reconstruction of a band-limited spectrum. Simulations are included for both the deterministic case and for sampled covariance matrices.

DOI:10.1049/ip-f-1.1985.0093

出版商:IEE    

年代:1985

数据来源: IET

摘要:

A convenient technique for the analysis of meteor-burst communication systems is presented, and it is shown how the probability densities of burst duration and burst interval can be predicted from the system parameters. The technique is based on an extension of generally accepted theory combined with experimental results, and a set of simple equations is obtained. The theoretical derivations are closely related to the physical phenomena involved. An experimental verification programme was undertaken in September 1982. The measurements made showed good agreement with the predicated values.

DOI:10.1049/ip-f-1.1985.0095

出版商:IEE    

年代:1985

数据来源: IET