TM 1-1520-238-10 Change 5 4-75 4.38 RADAR WARNING SYSTEM AN/APR-39A(V)1. The radar warning (RW) system provides visual and aural warnings of radar reception. This is done by receiving, processing, and displaying potential threats in the radio frequency (RF) environment. Potential threats are dis- played as symbols on the RW display and announced over the intercommunication system. The emitters that it displays are derived from the emitter identification data (EID) contained in the user data module (UDM) that is in- serted in the top of the digital processor. The UDM con- tains the electronic warfare threat data that goes to make up the specific library for a specific mission or geographi- cal location. When a match of the electronic warfare data occurs the processor generates the appropriate threat symbology and synthetic audio. The operating controls and indicators of the RW control panel (fig 4-20) are de- scribed in table 4-25. When installed, the AN/AVR-2A(V)1 laser detecting set provides early warning against laser threats. In the event of simultaneous warnings, one from the radar warning and one from the laser detecting set, the laser warning signals have priority. Refer to paragraph 4.39. Table 4-25. AN/APR-39A(V)1 Radar Warning System Control/Indicator Functions Control/ Indicator Position Function PWR ON Turns set on. Listen for synthetic voice message – APR 39 POWER UP. Plus (+) sign will appear and stabilize in center of CRT. OFF Turns set off. TEST When momentarily depressed initiates self-test confidence check except for antennas and antenna receiver cabling. MODE 1 Selects normal voice message format. 2 Selects terse/abbreviated voice message format. AUDIO Adjusts volume to the intercommunications system. 4.38.1 AN/APR-39A(V)1 Operating Procedures. The procedure for turning on and off the RW equipment is as follows: CAUTION To prevent damage to the receiver de- tector crystals, assure that the radar warning set antennas are at least 60 yards from active ground radar anten- nas or 6 yards from active airborne ra- dar antennas. Allow an extra margin for new, unusual, or high power emit- ters. Excessive indicator display bright- ness may damage the CRT. Set BRIL control for readable display. 1. Equipment on. PWR switch – ON. Listen for synthetic voice message – APR 39 POWER UP. Plus (+) sign will appear and stabilize in center of CRT. 2. BRIL – Adjust as desired for best indicator dis- play of + symbol. 3. MODE switch – Select for desired synthetic voice message format. 4. TEST – Press pushbutton to start system self- test. 5. AUDIO control – Adjust volume as desired. 6. Equipment off. PWR switch – OFF. (Pull PWR switch handle out to disengage lock.)