摘要:

The important factors are discussed. A new method is described for the direct visual observation of the phonocardiogram accompanied by a simultaneous electrocardiogram, or phonocardiogram plus sphygmogram, etc., at the patient's bedside. The heart sounds can be heard at the same time through a special electrical stethoscope which is incorporated in the apparatus.

DOI:10.1049/ji-3-1.1943.0012

出版商:IEE    

年代:1943

数据来源: IET

摘要:

The paper calls for a reconsideration of the aims of university courses for prospective engineers, with particular reference to prospective telecommunication engineers. It is argued that the situation created by the extremely rapid growth of scientific knowledge necessitates a more effective co-ordination of the engineering and physics teaching at the undergraduate stage and the introduction of full-time postgraduate courses. It is suggested that entry to an undergraduate engineering course should be preceded in all cases by a year of general practical training in industry and to a postgraduate course in Telecommunications by a year of experience in the practice of that branch of engineering work. Reference is also made to the need for greater attention to the development of student personality and of a sense of responsibility in social matters, and to the desirability of making greater provision for the transfer of outstanding National Certificate students to full-time university courses.

DOI:10.1049/ji-3-1.1943.0014

出版商:IEE    

年代:1943

数据来源: IET

摘要:

This paper, in continuation of Part 1, which has already been published in theJournal,1deals with the transmission of an amplitude-modulated wave through a bandpass channel the transfer characteristics of which are not symmetrical, either in modulus or phase, or both, about the carrier frequency. This paper is not concerned with any specific application of such asymmetric-sideband working; perfectly general forms of modulating wave and channel characteristics have been assumed. The theorem, given in Part 1, expressing the “equivalent modulation frequency characteristics” of such a channel in terms of the bandpass characteristics is here considered in greater detail.The idealized transfer characteristics chosen by various authors for analysis of asymmetric-sideband channel distortion are examined in the light of this theorem, as are also the characteristics of a generalized tuned circuit amplifier stage (or series of stages), taken as a practical example.The theorem is again extended to include the case of a carrier wave modulated by an envelope wave which rises or decays at a rate greater than that of the carrier itself (that is, a wave spectrum containing “negative” sidebands).An appendix is included, giving some notes on the waveform of such a modulated wave.

DOI:10.1049/ji-3-1.1943.0018

出版商:IEE    

年代:1943

数据来源: IET