CONTENTS

�1���� Introduction������
������� 1.1���� Daily meteorological operations������
������� 1.2���� Monitoring climate change��
������� 1.3���� Defence use�����������
������� 1.4���� Other users
�2���� Characteristics of radiosonde operation����
�3���� Radio-frequency spectrum used in WMO operations��������
������� 3.1���� Results from WMO survey
������� 3.2���� Radio-frequency spectrum occupied in Europe�������
������� 3.3���� Radio-frequency spectrum occupied in the United States of America����������
�4���� Operational requirements�
�5���� Future trends����
������� 5.1���� Very strong upper winds����
������� 5.2���� Manpower efficiency resulting from highly automated systems���������
������� 5.3���� Low radiosonde cost���������
������� 5.4���� Independence from international NAVAID systems
��� ����5.5���� Possible improvements to spectrum occupation from improved radiosondes
�6���� Radiocommunication characteristics of current radiosonde systems�����������
������� 6.1���� Transmitter characteristics��
������� 6.2���� Ranging signal��������
������� 6.3���� Receiving antennas���� �����