摘要:

The paper describes the provision that has been made at United Kingdom Coast Stations to meet the major requirement for ship/shore communications created by off-shore oil exploration and related activities. The constraints imposed by spectrum shortage and congestion are discussed and an indication given of the magnitude of traffic handled and the performance achieved. The use of developing techniques for future use is also discussed.

DOI:10.1049/ree.1980.0058

出版商:IERE    

年代:1980

数据来源: IET

摘要:

In an off-shore environment, as a general rule, communications need to be established directly between terminals with no provision for intervening repeaters. In planning terrestrial microwave communication networks, this imposes a requirement to use trans-horizon links to a greater extent than in land-based communications.The attendant problems of interference and practical methods for reducing such interference in terms of frequency planning, equipment design, and network power control are discussed.

DOI:10.1049/ree.1980.0059

出版商:IERE    

年代:1980

数据来源: IET

摘要:

This paper provides an outline description of the Post Office trans-horizon radio link services to off-shore oil/gas production platforms and takes a brief look into the future. It also compares the result of using different methods of predicting the statistical behaviour of the radio path transmission loss, and offers a possible method to give an estimate of the cumulative distribution of scatter loss for trans-horizon radio links operating in the North Sea.

DOI:10.1049/ree.1980.0061

出版商:IERE    

年代:1980

数据来源: IET

摘要:

This paper examines the conditions which would allow land mobile radio systems using spread-spectrum techniques to share certain r.f. channel allocations on a mutual non-interference basis with the existing users of these channels, namely the television broadcasters.An experimental spread-spectrum communication system has been developed and this has been used to examine the feasibility of bandsharing from the point of view of establishing protection for the television signal from the spread-spectrum interference for imperceptible visual interference on the screen, whilst still allowing adequate reception of the spread-spectrum signal under conditions of high television interference.The results indicate that the spread-spectrum signal must be at least 42 dB below the peak television carrier level at the television carrier frequency for picture quality to be unaffected, and under these conditions an output signal with at least 25 dB signal-to-noise ratio can be obtained from the spread-spectrum receiver.

DOI:10.1049/ree.1980.0062

出版商:IERE    

年代:1980

数据来源: IET

摘要:

This paper is concerned with shielded magneto-resistive replay head structures in which the sensitive magneto-resistive elements are displaced to be either nearer to one shield than the other or deep into the gap between the shields. These structures are analysed experimentally using a resistive paper analogue and theoretically using standard potential theory. It is found that ‘sideways’ displacement of the element has the effect of causing asymmetry in replayed pulse shapes, the amount of asymmetry decreasing with increasing head-to-medium separation. Shifting of the elements back into the gap is shown to result in significant reductions in signal amplitude but only minor increases in pulse width. Theory and experiment show reasonable agreement.

DOI:10.1049/ree.1980.0063

出版商:IERE    

年代:1980

数据来源: IET