Single-Sideband Operation for International Telegraph

The increased demands for multiple and direct international radiotelegraph channels between the nations of the world and the shortage of usable high-frequency spectrum has greatly increased the importance of the single-sideband radio system for this purpose. The world´s requirements for high frequencies, 4 mc to 30 mc, are so large that they are assigned over and over again to various services on the basis of geographical and time sharing. Single-sideband operation with multiple subcarriers and automaticfrequency control permit a high order of frequency utilization efficiency. Single-sideband operation offers a high degree of flexibility in meeting the various requirements of international communications. The number of its subcarriers can be changed to meet varying load conditions; they can be shifted to avoid temporary interference; and they can be used to operate with more than one point in the same geographical area. Codes with various numbers of signal elements either equal or unequal in length, and different types of modulation, and speeds can be carried on any or all subcarriers.