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Title: Automatic detection of radio-signal initiation with the H.F. band
Author: Rajappan, Kannazuthu Puthanmadam
Awarding Body: University of London
Current Institution: Imperial College London
Date of Award: 1965
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This thesis describes an investigation into the problem of designing an electronic system capable of automatically searching selected portions of the High Frequency (H.F) spectrum for possible new transmissions, and into the limitations and practical feasibility. When there is a priori knowledge of the various signal parameters such as type of modulation, frequency and time of transmission etc., various well known techniques can be used for the detection of the desired signal. But in the present problem under investigation, no such a priori knowledge may exist. Therefore we have to adopt special means of detection. Preliminary experiments have shown that the technique of scanning the selected portions of the H.F. spectrum, measuring the energies contained therein, and comparing these with some preset thresholds is one of great potential accuracy; but that certain problems associated with noise and fading need to be resolved. Experiments have been performed to study the fading effects and the effect of various types of noise in order to fix a threshold for detection. Experiments have also been performed to determine the probability of detection both as function of signal to noise ratio and signal duration. Finally the basic design considerations of an electronic system for detecting new signals in the H.F. spectrum is discussed in detail. The proposed system is straight forward and needs very little refinement. The important and most striking feature of the system is the possibility of saving vast amounts of manpower which would otherwise be needed for the monotonous and repetitive job of tuning a receiver for long hours of day and night.
Supervisor: Cherry, E. C. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available