{'fraction_non_alphanumeric': 0.01756440281030445, 'fraction_numerical': 0.00351288056206089, 'mean_word_length': 5.785714285714286, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Transmitter Elevation Angle Prediction of Near Vertical Incidence Skywave Communication Link

Near vertical incidence skywave (NVIS) is suitable for short distance (ground distance less than 400 kilometres) short-wave communication, and there are errors using the existing calculation methods of transmitter elevation angle in this communication range. This paper presents a synthetic method for predicting the transmitter elevation angle of NVIS links. According to whether the measured data can be obtained in the application area, different models are selected to predict the transmitter elevation angle. The accuracy of this method is verified by theoretical values constructed using three-dimonsional ray-tracing technology. The research results can be used for frequency selection and field strength prediction of short-range skywave communication.