DOI:10.1049/ree.1983.0003

出版商:IERE    

年代:1983

数据来源: IET

摘要:

The general behaviour of radio receivers with feedback automatic gain control is examined for a range of fading conditions. Mathematical modelling of the a.g.c. system as a non-linear servo-loop goes part of the way to characterizing the dynamical response. It is shown that the characteristics of practical aircraft receivers for u.h.f. voice communications are too complex for representation by simple models and extensive measurements are needed to assess their behaviour under realistic operational conditions. A measurement strategy is formulated and has been applied to several types of radio receiver. It is recommended that dynamical performance clauses be included in receiver specifications.

DOI:10.1049/ree.1983.0004

出版商:IERE    

年代:1983

数据来源: IET

摘要:

Anin situfluorometer capable of operation to 400 m is described. A pulsed xenon light source ensures low power consumption (6 W) and a high signal-to-noise ratio, giving a phytoplankton chlorophylladetection limit of 0.1 mg/m3. Operation at 8 knots in an undulator enables vertical profiles to be determined with a resolution of about 1 m. By changing the optical filters it is possible to detect the fluorescence of dyes, hydrocarbons, carbosol, etc., with similar high sensitivity.

DOI:10.1049/ree.1983.0005

出版商:IERE    

年代:1983

数据来源: IET

摘要:

As part of a research project into the cost effectiveness of training, various experiments were held in telephone exchanges in the UK. Data from those experiments and from other sources in the literature were used to compare the efficiency of a selection of models of learning.The method of comparison was based on an extension of an iterative two-parameter curve-fitting algorithm which used a Taylor series approximation of the function of the model of learning investigated.The most practical model found was the time-constant model sometimes known as the Bevis model.

DOI:10.1049/ree.1983.0007

出版商:IERE    

年代:1983

数据来源: IET

摘要:

A new analysis of the Adcock direction finder is presented in terms of phase-mode excitations associated with circular arrays. This leads to a convenient form of processing for such a d.f. system based upon a circular array/Butler matrix configuration which employs a direct phase-measuring detector for bearing measurements. The principal sources of error limiting the physical spacing of elements within the array are highlighted and methods of improving wide-bandwidth operation are presented which entail the use of directional elements. A signal processing system based around a small microcomputer is discussed for the automatic compensation of errors due to the finite number of elements.

DOI:10.1049/ree.1983.0008

出版商:IERE    

年代:1983

数据来源: IET

摘要:

The use of delta-sigma modulation for the realization of nonrecursive digital filters is described. The proposed method exploits the simplicity of the delta-sigma modulator for analogue to digital conversion. This method permits the use of a microprocessor for the realization of the filters without using an external fast multiplier. Moreover the experimental results have shown that the use of an 8-bit microprocessor can give satisfactory results.

DOI:10.1049/ree.1983.0009

出版商:IERE    

年代:1983

数据来源: IET