CHAPTER 1 INTRODUCTION TO RADIO-FREQUENCY COMMUNICATIONS

1-1 CHAPTER 1 INTRODUCTION TO RADIO-FREQUENCY COMMUNICATIONS LEARNING OBJECTIVES Learning objectives are stated at the beginning of each chapter. These learning objectives serve as a preview of the information you are expected to learn in the chapter. The comprehensive check questions are based on the objectives. By successfully completing the OCC/ECC, you indicate that you have met the objectives and have learned the information. The learning objectives are listed below. Upon completion of this chapter, you will be able to: 1. Define electrical telecommunications. 2. Describe the use of radiotelegraph, radiotelephone, teletypewriter, and facsimile. 3. Define and describe the interrelationships of the system, set, group, unit, assembly, subassembly, part, and reference designations. 4. State the frequency ranges of the various frequency bands and describe the most common uses of those bands by the Navy. 5. Describe a strategic communications link. 6. Describe a tactical communications link. 7. Describe the five basic communications modes of operation. 8. Describe a switched communications network. 9. Describe the purpose of the two Navy-only networks. INTRODUCTION TO NAVAL TELECOMMUNICATIONS When the wireless (radiotelegraph) was invented, the Navy saw a possible use for it. It could be used for communications from shore stations to ships along the coast. In 1899, the first official naval radio message was sent from ship to shore. It only traveled a distance of 20 miles but that was a start. The next advance was in 1916 when the Navy first used radiotelephone between ships. Three years later the first airborne radio was used to communicate with a ground station. In the early years, communications was not the best because of poor tuning techniques. Receivers often did not pick up the signal. This problem was almost eliminated in 1931 when the first superheterodyne receivers were installed in the fleet. In 1944, another important event took place. The first successful radio teletypewriter transmissions between ships were completed. The first successful use of radiophoto (facsimile) occurred in 1945 with the transmission of the surrender document signing that ended World War II. Naval communications has grown tremendously in size and complexity since then.