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Stocker, A. J.
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- PublicationOpen AccessAspects of HF radio propagation(2009-08)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Warrington, E. M.; Department of Engineering, University of Leicester, UK ;Bourdillon, A.; IETR, Université de Rennes 1, France ;Benito, E.; Electromagnetism and Radar Department, Onera, Palaiseau, France ;Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Monilie, J. P.; Electromagnetism and Radar Department, Onera, Palaiseau, France ;Muriuki, M.; Department of Engineering, University of Leicester, UK ;Pietrella, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Rannou, V.; Electromagnetism and Radar Department, Onera, Palaiseau, France ;Rothkaehl, H.; Space Research Centre PAS 00-716 Warsaw, Poland ;Saillant, S.; Electromagnetism and Radar Department, Onera, Palaiseau, France ;Sari, O.; Aselsan A.S., Macunkoy, Ankara, Turkey ;Stocker, A. J.; Department of Engineering, University of Leicester, UK ;Tulunay, E.; ODTÜ/METU, Department of Electrical and Electronics Engineering, Ankara, Turkey ;Tulunay, Y.; ODT /METU, Department of Aerospace Engineering, Ankara, Turkey ;Zaalov, N. Y.; Department of Engineering, University of Leicester, UK; ; ; ; ; ; ; ; ; ; ; ; ; ; The propagation characteristics of radio signals are important parameters to consider when designing and operating radio systems. From the point of view Working Group 2 of the COST 296 Action, interest lies with effects associated with propagation via the ionosphere of signals within the HF band. Several aspects are covered in this paper: a) The directions of arrival and times of flight of signals received over a path oriented along the trough have been examined and several types of propagation effects identified. Of particular note, combining the HF observations with satellite measurements has identified the presence of irregularities within the floor of the trough that result in propagation displaced from the great circle direction. An understanding of the propagation effects that result in deviations of the signal path from the great circle direction are of particular relevance to the operation of HF radiolocation systems. b) Inclusion of the results from the above mentioned measurements into a propagation model of the northerly ionosphere (i.e. those regions of the ionosphere located poleward of, and including, the mid-latitude trough)and the use of this model to predict the coverage expected from transmitters where the signals impinge on the northerly ionosphere. c) Development of inversion techniques enabling backscatter ionograms obtained by an HF radar to be used to estimate the ionospheric electron density profile. This development facilitates the operation of over the horizon HF radars by enhancing the frequency management aspects of the systems. d) Various propagation prediction techniques have been tested against measurements made over the trough path mentioned above, and also over a long-range path between Cyprus and the UK. e) The effect of changes in the levels of ionospheric disturbances on the operational availability at various data throughput rates has been examined for the trough path mentioned earlier. The topics covered in this paper are necessarily brief, and the reader is referred to full papers referenced herein on individual aspects.480 575 - PublicationOpen AccessPropagation of HF radio waves over northerly paths: measurements,simulation and systems aspects(2004)
; ; ; ; ; ;Warrington, E. M.; Department of Engineering, University of Leicester, U.K. ;Stocker, A. J.; Department of Engineering, University of Leicester, U.K. ;Zaalov, N. Y.; Department of Engineering, University of Leicester, U.K. ;Siddle, D. R.; Department of Engineering, University of Leicester, U.K. ;Nasyrov, I. A.; Department of Engineering, University of Leicester, U.K.; ; ; ; Large deviations in the direction of arrival of ionospherically propagating radio signals from the Great Circle Path (GCP) have serious implications for the planning and operation of communications and radiolocation systems operating within the HF-band. Very large deviations are particularly prevalent in the polar and sub-auroral regions where signals often arrive at the receiver with bearings displaced from the great circle direction by up to ±100° or more. Measurements made over several paths are presented in this paper, and the principle causes of off-great circle propagation outlined. Significant progress has been made in modelling the propagation effects and work is now in hand to incorporate the results into tools to aid the planning and operation of HF radio systems operating at northerly latitudes.274 2226 - PublicationRestrictedTime of flight measurements over a radio link from Uppsala to Bruntingthorpe and their application to testing predictions methods that approximate the ray tracing technique(2009-07-01)
; ; ; ; ;Pietrella, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Warrington, E. M.; Department of Engineering, University of Leicester, LE1 7RH, UK ;Stocker, A. J.; Department of Engineering, University of Leicester, LE1 7RH, UK ;Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; ; Time of flight measurements (TOF) over the radio link between Uppsala (Tx: 59.9°N, 17.6°E) and Bruntingthorpe (Rx: 52.5°N, 1.1°W) have been performed every 2 min at six frequencies (4.637, 6.954, 8.008, 10.391, 11.118, and 14.364 MHz) during the period November 2006–January 2008. Such measurements have been compared with the TOF provided by three prediction methods that approximate the ray tracing technique: IRI-95, SIRM&BR_D, and ICEPAC. The root mean square deviation (rms) between TOF monthly median measurements and TOF monthly median predictions and the differences (DP) between the length of the median and predicted ray path have been calculated. The results, which are presented in terms of rms and DP for different seasons and different time periods, have indicated that the approximate methods are inadequate and that for more accurate predictions ray tracing techniques should be applied.341 30