ISSN:0377-2063    

DOI:10.1080/03772063.1967.11485468

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

摘要:

ABSTRACTThe degree of optimization of a feedback-control system is often assessed in terms of certain forms of integral functions of the system error under step-input disturbances. The integrals are to be evaluated either by numerical programming on a digital computer or by analog instrumentation. This paper†presents a method of straight line approximation which permits the expression of the various integral criteria as relatively simple algebraic functions of the step-transient parameters of the system, namely the rise-time, settling time and the times and values of the first and second over-shoots. Since these are easily read off, either from a recording or on an oscilloscope, one has a quick and easy method of index evaluation. The values obtained by using the simplified formulae are compared with those obtained by actual integration for typical systems. The reliability of the formulae, particularly for comparison of systems, is discussed.

ISSN:0377-2063    

DOI:10.1080/03772063.1967.11485469

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

摘要:

ABSTRACTThe present paper deals with the design of one type of balanced mixers that are currently used in modern radar receivers. The use of a cross-bar configuration ensures compactness in size of the mixer and thus enables it to be employed in radars where space is at premium. The experiments carried out on the Laboratory model indicated that the mixer, when used with an IF amplifier of 3·5 db. noise figure, gives an overall noise figure of 11 db. and an isolation better than 20 db. between the signal and local oscillator arms over a range of 1 Gc/s. at X-band.

ISSN:0377-2063    

DOI:10.1080/03772063.1967.11485470

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

摘要:

ABSTRACTThe paper describes the results of observations over three transhorizon radiopaths. The observed data during significant stratifications in the upper air show considerably low path loss as compared to long-term median transmission loss predicted by CRPL method. The dependence of transmission loss on layer characteristics of the troposphere is discussed and a method for prediction suggested. The signal level determined from reflection theory for large layers has been found to agree with observed level during occurrence of large elevated layers. A simple approach towards system planning based on these results is briefly indicated.

ISSN:0377-2063    

DOI:10.1080/03772063.1967.11485471

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

摘要:

ABSTRACTThe variability of the critical frequency of the F2-layer (f0F2) has been investigated by finding the standard deviation (σ) of the hourly values of f0F2from the monthly mean values (f). The ratio in low as well as in high sunspot years has been computed for three representative months and its daily variation studied at three stations, namely Kodaikanal, Ahmedabad and Tokyo. The proportionate variability in f0F2is generally found to be more during night time than during day time. The deviations in f0F2are found to be more in low sunspot years than those in high sunspot years for both day time and night time f0F2at Ahmedabad, for night time f0F2at Kodaikanal and for day time at Tokyo. It is indicated that the present practice of choosing optimum working frequency (OWF) as 85 per cent of the predicted maximum usable frequency (MUF) may not effectively take care of the day-to-day fluctuations in the MUFs. A higher margin of safety has to be considered for better reliability of transmissions via the F2-layer at mid latitudes.

ISSN:0377-2063    

DOI:10.1080/03772063.1967.11485472

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

摘要:

ABSTRACTWith the advent of Silicon-controlled rectifier, there has been a tremendous interest in the solid static inverter technology. This paper first discusses the various principles of inverter circuits and describes at length the widely used Capacitor-Commuted parallel inverter circuit. It then discusses the various methods of inverter voltage control and of converting the square wave output into sinusoidal. The paper concludes with a detailed description of a 4 kVA. static inverter designed at the Telecommunication Research Centre for use in‘No break’power plants for carrier communication equipment, coaxial and microwave systems.

ISSN:0377-2063    

DOI:10.1080/03772063.1967.11485473

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

ISSN:0377-2063    

DOI:10.1080/03772063.1967.11485474

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

ISSN:0377-2063    

DOI:10.1080/03772063.1967.11485475

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

ISSN:0377-2063    

DOI:10.1080/03772063.1967.11485476

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

ISSN:0377-2063    

DOI:10.1080/03772063.1967.11485479

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor