Abstract
In order to gather information about the occurrence of ducting/superrefraction and signal‐fading effects at frequencies around 300 MHz with antenna heights appropriate to intership communications, an experimental investigation has been undertaken with a transmitter and two receivers deployed in the British Channel Islands. Signal strength measurements made over a period of 17 months for a path from Jersey to Guernsey from April 2001 to September 2002 and 8 months of data for a path from Jersey to Alderney from November 2001 to September 2002 have been analyzed. Comparisons have been made between the received signal characteristics and several meteorological parameters such as sea state, weather conditions, and season, and the statistics of the occurrence of enhancements in signal strength due to superrefraction and ducting are presented.
Highlights
[3] In order to gather information about the occurrence of superrefraction/ducting and signal-fading effects at frequencies around 300 MHz with antenna heights appropriate to intership communications, an experimental investigation has been undertaken with a transmitter and two receivers deployed in the British Channel Islands
[20] rough sea states or high wind speeds were observed on a number of occasions, there were only three occasions during spring 2001 on different days during which the propagation appeared to be influenced by rough sea conditions
Comparisons have been made between the received signal characteristics and several meteorological parameters such as sea state, weather conditions, season, etc
Summary
Two receiver sites were installed providing unobscured (by islands, etc) over-sea paths: the first (March 2001) in St Peter Port, Guernsey (33.3 km), and the second (November 2001) on the south coast of Alderney (48 km). Measurements were made over the path to Guernsey for a period of approximately 17 months. [5] In the data presentation, receiver power levels are quoted on a logarithmic scale on which 0 dBr corresponds to a power input to the receiver of À107 dBm This value is a dB or so less than the signal power that causes the automatic gain control (AGC) to come into effect. It should be noted that the actual day to day levels vary [9] It is not the purpose of this paper to develop or to extensively reproduce the theory of VHF/UHF propagation over the sea, rather to present measurements of signal strength variations, and to interpret these measure-
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