摘要:

The year 1957 marked the beginning of the International Geophysical Year and the satellite era, and this review describes the most important developments in ionospheric science since then. The discoveries made by different techniques concerning the nature and formation of the D, E and F layers and their various anomalies are considered and the relationship between the ionosphere and the region above it, the magnetosphere is briefly discussed.

DOI:10.1049/ree.1975.0003

出版商:IERE    

年代:1975

数据来源: IET

摘要:

Since the ionosphere is produced by the quiet Sun and disturbed by the active Sun, short-term ionospheric forecasting is discussed in three stages:(1) forecasting the solar activity;(2) the relations between the solar activity and geophysical disturbances, particularly magnetic storms, daylight fadeouts and polar cap absorption;(3) the effects of these geophysical disturbances on the ionosphere and on ionospheric radio communications.A short history of the subject is given, the international arrangements for collecting and rapidly exchanging the required solar and geophysical data are outlined, and short-term forecasting services at present operating are described briefly.

DOI:10.1049/ree.1975.0004

出版商:IERE    

年代:1975

数据来源: IET

摘要:

When an h.f. radio circuit is being planned, the specification of the transmitter frequency range and radiated power and the choice of transmitting and receiving aerials are determined from propagation considerations. The factors involved in prediction techniques for the case of ionospheric signals are outlined. Current procedures used internationally and their proposed future improvements are described.

DOI:10.1049/ree.1975.0005

出版商:IERE    

年代:1975

数据来源: IET

摘要:

A brief history is given of the CCIR with its Study Group structure, in particular Study Group 6 on Ionospheric Propagation. The system of documentation is described with special reference to the Reports which form a most valuable source of information on ionospheric propagation in relation to radio communication. The nine Working Groups under which the work of Study Group 6 is organized at the Interim and Final Meetings are considered in turn, and reference is made to the cooperation with URSI in the more scientific aspects of the work. The part played by the CCIR as a subsidiary body of the ITU is explained in providing the basic information required by the IFRB and the planning experts at ITU Conferences.

DOI:10.1049/ree.1975.0006

出版商:IERE    

年代:1975

数据来源: IET

摘要:

An outline is presented of the theoretical methods available for determining the propagation characteristics of v.l.f. and l.f. waves for both long and short transmission paths. Attention is drawn to the differences between the ray-hop and wave guide mode theories which have been applied to these frequency bands.The experimental study of v.l.f./l.f. propagation is discussed and the variations in the phase and amplitude of the received signals during normal and disturbed conditions are described. A comparison is made between the experimental results and those predicted from theoretical considerations. Some examples are given of the application of v.l.f./l.f. waves to navigation (mainly Omega) and to communications.

DOI:10.1049/ree.1975.0007

出版商:IERE    

年代:1975

数据来源: IET

摘要:

The principles of high frequency direction finding are briefly described and the main sources of error in these systems discussed. The deviations in bearing produced by travelling ionospheric disturbances (t.i.d.s) are considered in detail since these errors are particularly difficult to predict and correct. General background information on the physics of t.i.d. phenomena has been included and attention given to the source mechanism and propagation characteristics of the disturbances. The paper concludes with a review of some possible methods for the correction of t.i.d. induced errors and details are given of some recent investigations of error correction procedures.

DOI:10.1049/ree.1975.0008

出版商:IERE    

年代:1975

数据来源: IET

DOI:10.1049/ree.1975.0009

出版商:IERE    

年代:1975

数据来源: IET

摘要:

The generator may be used off-line or on-line to a computer. It is used principally for integrated-circuit mask generation but is also suitable for other precision pattern-drawing applications. The generator accepts commands to draw line segments, to outline or scan rectangles, and to replicate patterns in regular arrays (step-and-repeat). The output of the generator comprisesxandyco-ordinate-direction pulses. The organization of the instrument allows the later addition of other pattern modules. The instrument is constructed from off-the-shelf TTL. The advantage of the generator, compared to earlier models, is the great economy it effects with respect to the bulk of input-data medium or to the density of data on the computer interface line.

DOI:10.1049/ree.1975.0010

出版商:IERE    

年代:1975

数据来源: IET