TM  1-1520-240-10            3-2-21 CONTROLS/ INDICATOR FUNCTION c. Press EDIT line-select switch, then use CURSOR and VALUE switches to manually select an address character-by-character. (NOTE: NET INOP advisory is displayed if a selected channel or net contains: no data or corrupted data; or hardware cannot support the selected mode).  Press mi- crophone PTT switch CALL- ING is displayed LINKED is displayed with a short gong tone and headset audio is re- stored when link established. Start transmission. The sys- tem terminates the link and returns to ALE scanning after a period of inactivity (30 sec- onds typical). GPS position can also be transmitted by using the steps above plus the Transmit Position Report steps. ALE Link Protection Time Sync Press PTT switch or SYNC line-select switch. System re- turns to scan and the net de- fault address if sync success- ful, but if unsuccessful press ABORT line-select switch to return to ALE screen. ECCM Net Initializa- tion Set function switch to T/R and mode switch to ECCM. (NOTE: If ECCM data or keys are not loaded for net selected, a CHANNEL INOP advisory is displayed). Set channel/net switch to desired net. If selected channel is an ALE/ECCM channel, the ad- dress of station being called is displayed on line two. (NOTE: NET INOP advisory is displayed if selected chan- nel or net contains: no or cor- rupted data; or hardware cannot support selected mode. If screen displays UN- TUNED or UNSYNC adviso- ries proceed with system Tune/Sync operation, other wise proceed with ECCM op- eration. CONTROLS/ INDICATOR FUNCTION ECCM Tune/Sync Operation Press either TUNE line-select switch or microphone PTT switch to initiate combined tune and sync. TUNING fol- lowed by SYNCING is dis- played during process. Sys- tem, will return to ECCM screen without UNTUNED and/or UNSYNC advisories if successful. ECCM Operation Use -SQL switch to set squelch to TONE. Adjust VOL control for comfortable listening level. Use SQL + switch to set squelch to 0. If channel is noisy, set to 1. Higher settings are not rec- ommended for ECCM opera- tion. ECCM Operation - Receiving Calls RCVING PREAMBLE and/or INCOMING CALL is dis- played. ECCM Operations - Transmitting Press microphone PTT switch. Wait for preamble tones to cease then begin communications. If an ALE/ ECCM channel is used, CALLING is displayed while call in process. LINKED is displayed and a short gong tone sounds, and headset audio is restored when link established. (NOTE: Press ABRT line-select switch to abort calling process). Call initiator should make first transmission. The system ter- minates link and returns to scan after a period of inactiv- ity (30 seconds typical). GPS position can also be trans- mitted by using the steps above plus the Transmit Position Report steps. Data Messages The ARC-220 radio set can store up to 10 transmit and 10 received data messages up to 500 characters long each. Received data mes- sages are stored in memory and can be retransmitted.