| 摘要 |
<p>This invention is for a method and apparatus for determining the presence of thermal activity (13) in a volume of atmosphere (12), and has particular application in enabling and prolonging the flight of unpowered aircraft (16) and model aircraft such as gliders and hang-gliders. This is accomplished by using a suitable antenna (10) at ground level (11) and transmitting substantially vertically into the atmosphere a plurality of acoustical pulses of between 100 to 200 milliseconds duration at a frequency of about 6 kHz, each pulse separated by up to several seconds. The back-scattered signals which are primarily caused by thermal activity are received by a suitable receiver, and by use of appropriate circuitry or microprocessor the signals are analysed first by measuring the amplitude, then digitising the signals according to a threshold value, and finally integrating the signals over a number of received times so as to provide a cumulative signal, or scan, which then provides an indication of the thermal activity within the volume of air that back-scattered the signals. Over a number of scans, the history and the evolution of the thermal activity of the air being sampled is therefore provided. The apparatus may be positioned on the ground (11) or on an aircraft (16) and may also be located at remote locations and to provide information by appropriate communications. The method and apparatus thus enable a pilot (17) to utilise the existence of any thermals (13) that will enable them to prolong or improve their flight by steering the craft into the volume (12).</p> |
