tailieunhanh - Wireless Data Technologies reference phần 2

các kênh thông tin liên lạc (trong trường hợp này là Internet). Sự chậm trễ quá mức sẽ có nghĩa là khả năng này bị hạn chế. Các biến thể trong sự chậm trễ này (jitter) có thể có thể chèn tạm dừng hoặc thậm chí phá vỡ những từ khó hiểu thông tin liên lạc bằng giọng nói. | 4 A HISTORY OF WIRELESS TECHNOLOGIES In its March 1897 issue McClure s Magazine presented a long illustrated article entitled Telegraphing Without Wires by . Dam describing the experiments of Hertz Dr Chunder Bose and the youthful Marconi. Telegraph Age New York in its issues of November 1 and November 15 1897 reprinted a long article from the London Electrician entitled Marconi Telegraphy. This article consisted chiefly of the technical description that accompanied Marconi s British patent specification number 12039 of 1896. In September 1899 during the International Yacht Races held off of New York harbor the steamer Ponce was equipped with radio devices by Marconi for the purpose of transmitting reports on the progress of the race. Two receiving stations were equipped one on the Commercial Cable Company s cable ship Mackay Bennett stationed near Sandy Hook and connected with a land line station on shore by means of a regulation cable the other at Navasink Highlands. This demonstration even though it wasn t very successful immediately brought the subject to the front in the United States interest. In 1900 the erection of the first Marconi station at Cape Cod Massachusetts began. In March 1901 the Marconi Company installed radio devices at five stations on five islands of the Hawaiian group. For a long time these installations were to prove to be of little or no value due to the restricted availability scarcity of qualified operatives. During this same year the Canadian government installed two stations in the Strait of Belle Isle also constructed were the New York Herald stations at Nantucket MA and Nantucket light ship. The greatest radio event of 1901 was the reception by Dr Marconi at St Johns Newfoundland of what has become known as the famous letter S transmitted as a test signal from his English station this was on December 11 1901. In 1904 several US government agencies which included the Navy the Department of Agriculture and the Army s Signal Corps