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cách tốt nhất để làm như vậy là làm cho một truyền dẫn tương tự như này: "Đây là NØAX tháng mười một của Zero Alpha X-ray điện thoại di động trên đường Interstate 90. Bất kỳ ai xung quanh "Lặp lại truyền này một vài lần, cách nhau một vài giây ngoài. | Chapter 11 Specialties 207 Slow-scan television SSTV and Facsimile Fax Pioneered back in the 1960s slow-scan has re-emerged in the last ten years as a popular image mode. You can find slow-scan primarily on HF where SSB voice transmission is the norm. The name comes from the fact that transmitting the picture over a narrow channel made for voice transmissions takes several seconds. You can send slow-scan pictures using a commercial scan-converter that converts the regular camera video to slow-scan formats and an HF transceiver. SSTV enthusiasts are rapidly eliminating the standalone converters in favor of a computer with a video camera interface and a sound card. Software is used both to convert the camera video to data files and to encode and decode the data files as audio that can be transmitted and received with a voice SSB transceiver. You can usually hear slow-scan signals in the vicinity of 14.230 and 21.340 MHz using USB transmissions. Depending on the picture format you use the signals make a loopy loopy loopy sound with the video and color information being encoded as different audio tones. Other tones mark the edges of the picture frame. Each loop is one line of picture. Data file transmissions may sound more like multiple tones mixed together. Facsimile-over-radio was at one time a very widely used method of obtaining weather information from land-based and satellite stations. Transmissions of Group I and Group II facsimile standard signals could be successfully made via ham radio transceivers as well. The use of standalone fax machines and modems never very widespread is rapidly disappearing in favor of transmitting the images as data files just as with SSTV. Regular fax images can still be received from orbiting weather satellites however. The software packages that transmit data files as SSTV images often make no distinction between data captured from video and data received from a fax service. You will find many good links to detailed information .
