Đang chuẩn bị liên kết để tải về tài liệu:
Ham Radio for Dummies 2004 phần 6

Du khách đến khu vực của bạn thường xuyên điều chỉnh các tần số, theo dõi họ là một cách tốt để làm cho du khách cảm thấy chào đón hoặc cung cấp cho các hướng. Nếu bạn đang đi du lịch và muốn làm cho một số liên lạc trên đơn kêu gọi fre quencies, | 166 Part III Hamming It Up Thousands of hams across the continents and around the world like nothing better than to make contacts QSOs with someone far away. These hams seem to ignore all nearby stations. Their logs are filled with exotic locations. Ask them about some odd bit of geography and you are likely to find that they not only know where it is but some of its political history and the call sign of at least one ham operator there. These hams are DXers. The history of ham radio is tightly coupled to DX-ing. As transmitters became more powerful and receivers more sensitive the distances a station could make contact were a direct measure of quality. Hams quickly explored the different bands and follow the fluctuations of the ionosphere. DX-ing drives improvements in many types of equipment. Today intercontinental contacts on the HF frequencies traditionally considered to be the shortwave bands are common but still thrilling. Cross-continental contacts on VHF and UHF once thought impossible are made in increasing numbers. Because the sun and the seasons are always changing each day you spend DX-ing is a little and sometimes a lot different. Sure you can log on to an Internet chat room or send e-mail around the world but like fishing logging a QSO in the log mastering the vagaries of the ionosphere and getting through to a distant station is a real accomplishment nonhams can never know. DX-ing on the shortwave bands The following sections show you how to use the shortwave or HF bands to work DX. These are the bands with frequencies below 30 MHz on which signals routinely travel all over the Earth bouncing between the ionosphere and the Earth s surface as they go. The ease with which signals can be exchanged between continents on the shortwave bands attracts many thousands of adherents. Because the signals propagate so widely HF DX-ing is often a worldwide event with stations calling from several .