High-Frequency Systems

5. 6. 7. (AF) to direct current (dc) for use by the teleprinter equipment. Black dc Patch Panel— The dc output of the AN/UCC-1 is fed to the SB-1203/UG DC Patch Panel. The dc patch panel permits the signal to be patched to any cryptoequipment (discussed later) desired. Cryptoequipment— The cryptoequipment decrypts the signal and connects its output to the red SB-1210/UGQ DC Patch Panel. Red dc Patch Panel— The SB-1210/UGQ can be patched to a selected printer that prints the signal in plain readable text. HIGH-FREQUENCY SYSTEMS The high-frequency (HF) band (3-30 MHz) is primarily used by mobile and maritime units. The military uses this band for long-range voice and teleprinter communications. This band is also used as a backup system for the satellite communications system. We will discuss satellite communications later in this chapter. Figure 1-2 shows a typical high-frequency transmit system. In transmitting teleprinter information, the equipments shown in figure 1-2 perform the same functions as the equipments shown in figure 1-1, except the equipments in the high-frequency system do the functions in reverse order. In the HF transmit system, the AN/UCC-1 Telegraph Terminal converts dc signals into audio tone signals. The output of the AN/UCC-1 is connected to the transmitter transfer switchboard. The C-1004 Transmit Keying and Receive Control/Teleprinter is used to key the transmitter during teleprinter operations. Voice communications from some remote locations are also connected to the transmitter transfer switchboard. Voice communications are initiated at a handset (remote phone unit) and connected to the C- 1138 Radio Set Control. The output of the radio set control is connected to the transmitter transfer switchboard. The transmitter transfer switchboard permits the operator to select the proper transmitter for the frequency to be transmitted. Figure 1-2.—High-frequency transmit system. 1-3