DOI:10.1049/ree.1973.0088

出版商:IERE    

年代:1973

数据来源: IET

摘要:

This paper reports on an investigation into the application of data compression techniques as a means of reducing the ‘on-ground’ data storage requirements that are associated with many space research programmes. The paper presents and compares quantitatively various compression techniques based on the Shannon-Fano, ‘run-length’ and Hadamard transformation methods of source encoding. The compression ratios obtained when applying the techniques to actual satellite data are given and some new basic theory relating to ‘run-length’ encoding is presented.

DOI:10.1049/ree.1973.0089

出版商:IERE    

年代:1973

数据来源: IET

摘要:

Non-linear resistors have been known since the early 19th century but have been of commercial significance only over the last 50 years. Today over 700 million pieces are manufactured annually. This paper outlines the three major types commonly found in the electronics industry, namely, negative and positive temperature coefficient thermistors, and voltage-dependent resistors. The electrical properties of each type are examined and from these various fields of application are derived.

DOI:10.1049/ree.1973.0090

出版商:IERE    

年代:1973

数据来源: IET

摘要:

The relationship between system error probability and transmitter power is investigated for block and convolutional codes operating in conjunction with binary phase-reversal keying. The following assumptions are made: (i) all systems accept the same data rate, (ii) a very large bandwidth expansion is not acceptable, (iii) the channel is disturbed by white Gaussian noise, (iv) a matched filter receiver is used.The performances of these coded systems are compared with those of optimal binary andM-ary modulation schemes to give an indication of the systems to be considered in order to achieve efficient use of transmitter power for given system bit error probabilities.

DOI:10.1049/ree.1973.0091

出版商:IERE    

年代:1973

数据来源: IET

摘要:

It is shown that if the loss in a delay line is compensated by amplifying, the dynamic range of the system is maximized by amplifying continuously along the delay line so that the signal strength remains constant. This principle is particularly applicable to microsound delay lines and delay equalizers. Moreover, if the noise figure of the amplifier is sufficiently small,the dynamic range may be greater than in the line without amplification, although it will never exceed that of a lossless line.

DOI:10.1049/ree.1973.0092

出版商:IERE    

年代:1973

数据来源: IET

摘要:

Impatt diode amplifiers are candidates for use in super high frequency (s.h.f.) systems as broadband,intermediate power amplifiers, but their poor linearity makes them unattractive for some systems.The linearity of some X—band impatt diode amplifiers is considered in this paper. The amplifiers are of the circulator coupled, reflexion type, where p +nn + silicon diodes of various doping levels are operated in the impatt mode.The impatt class of diodes shows a r.f.negative resistance that depends on the r.f. voltage, so that the design of linear amplifiers using passive circuitry is empirical. The structure of the diode chip determines the spatial distribution of the electric field which, in turn, determines the value of the negative resistanceand its dependence on r.f. power. A range of theoretical? W mesa structures has been investigated to get a computed, optimum, linear amplifier at a frequency of 12 GHz, where the optimizingparameter is the choice of passive stepped impedance transformer. The computations show that somewhat better linearity can be obtained with lower-doped diodes than with the higher—doped diodes used in the design of impatt oscillators. The characteristics of experimental amplifiers using relatively highly—doped diodes are presented and show good qualitative agreement with the computed responses.

DOI:10.1049/ree.1973.0093

出版商:IERE    

年代:1973

数据来源: IET

摘要:

A design procedure is given for crystal lattice filters with bandwidths for quartz of approximately 1 to 8% of the centre frequency; the method results in simple formulae in terms of the elements of a low-pass ladder whose order is a multiple of four.

DOI:10.1049/ree.1973.0094

出版商:IERE    

年代:1973

数据来源: IET

DOI:10.1049/ree.1973.0095

出版商:IERE    

年代:1973

数据来源: IET