TM 1-1520-238-10 3-16 The WOD is initially entered into the preset memory and then transferred to volatile memory. After transfer, if power is lost or if channel 20 is selected when the function switch is set to PRESET, it will be necessary to perform another transfer from the preset memory to volatile memory. Start with channel 20 and set to progressively lower channels until a double beep is heard. The radio will not function in the AJ mode if a WOD is not in volatile memory. If the AJ mode is selected without en- tering a WOD into the volatile memory, a steady warning tone will be heard in the headset. (2) TOD. Time synchronization is provided by a clock inside the radio. The internal clock is turned off when the radio is turned off. A TOD signal must be received to reset the radio’s internal clock when the radio is turned on. This signal may be pro- vided by another HQ radio or by an external time distribu- tion system. Improper synchronization will prohibit proper communication. Reception of garbled communications in the AJ mode indicates the receiving radio and transmitting radio are not in synchronization. In a multiple radio net, the radio receiving all transmissions garbled is the radio that is out of synchronization. TOD reception can be performed in both normal and AJ modes. The radio automatically accepts the first TOD message after the radio is turned on and the WOD is transferred to volatile memory. Subsequent messages are ignored unless the T position is selected by the A-3-2-T switch. The radio may be resynchronized by setting the radio to the TOD transmission frequency, setting the A-3-2-T switch to T, and requesting another person in the common net to transmit the TOD. The radio then accepts the next TOD update, provided the TOD update arrives within one minute of selecting the T position on the A-3-2-T switch. TOD is normally received by the main or guard receiver via a prearranged frequency from another HQ radio which has the desired time. When the radio receives the TOD from an external timing source, it updates/synchronizes the radio’s internal clock with the timing source. This al- lows all radios in synchronization with the source and one another to frequency hop simultaneously for uninterrupted communication. Any arbitrary time may be used, but oper- ators are encouraged to obtain and use Universal Time Coordinated (UTC) time. The use of UTC time will allow operators to switch from one HQ radio net to another with- out retiming their radios to arbitrary times (TODs). If no TOD is available from another HQ radio, an emer- gency start of the TOD clock can be performed using the T position of the A-3-2-T switch and the TONE button. Emergency startup of the TOD clock generates an arbi- trary TOD that must be transferred to other radios using the same net. Operators using the emergency startup method will not be able to communicate in the AJ mode with anyone that has not received this arbitrary TOD. The net should update to UTC time as soon as possible so ev- eryone entering or leaving the net will not have to retime their radios. The TOD can be transferred in both normal and AJ mode by momentarily pressing the TONE button with the A-3-2-T switch set to T. A TOD transmission allows a time update if one radio has drifted out of synchronization. (3) Common Net Numbers. In the AJ mode, a communications channel is defined by a net number instead of a signal frequency as in the normal mode. After WOD and TOD are entered, any valid AJ net number can be selected by using the frequency selector switches. The net number programs the entry point in the WOD fre- quency hopping pattern, allowing for multiple radio net op- eration using a common WOD and TOD. f. Anti-Jamming Mode Operation. The A position of the A-3-2-T switch overrides the hundreds digit in both manual and preset modes. The A cannot be inserted into the preset channel memory. It will be displayed as a 3 on the frequency indicator, and accepted as a 3 if inserted in a preset channel. If the next three digits of a frequency in a preset channel are the same as the desired net number, the preset channel can be used in the AJ mode. The radio will function in the AJ mode when a WOD and TOD are programmed into the radio, A is set on the A-3-2-T switch, and MANUAL is selected on the function switch with an appropriate net number in the three fre- quency digits following the A. If the function switch is set to BOTH and the AJ mode is selected, any transmission on the guard channel takes precedence over the AJ mode.